10. laser technologies- a step forward for small and medium enterprises

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Laser technologies: a step forward for small and medium

enterprises

INTERNATIONAL CENTRE

FOR SCIENCE AND HIGH TECHNOLOGY



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The opinions expressed in this publication do not necessarily reflect the views of theUnited Nations Industrial Development Organization (UNIDO) or the International Centrefor Science and High Technology (ICS). Mention of firms’ names and commercial productsdoes not imply endorsement by UNIDO or ICS.

Any specifications or costs contained in this publication are for reference only; they reflectthe market conditions at the time of writing.

All pictures are in low definition in order to facilitate downloading and may not reflect thetrue finish of products. For more defined pictures the reader should refer to ICS UNIDO.

No use of this publication may be made for resale or for any other commercial purposewhatsoever without prior permission in writing from ICS.

Cover page insets include pictures of laser applications (from left to right, from top todown):□ marked metal component;□ 2D cut on stainless steel sheet;□ Cut and marked clothing items.

Thanks go to all the companies and institutions mentioned in the chapter on ‘SOURCESOF INFORMATION‘and also to those that shared their know-how but prefer not to benamed.

ICS-UNIDO is supported by the Italian Ministry of Foreign Affairs

© United Nations Industrial Development Organization and the International Centre forScience and High Technology, 2008

High Technology and New MaterialsInternational Centre for Science and High TechnologyICS-UNIDO, AREA Science ParkPadriciano 99, 34012 Trieste, ItalyTel.: +39-040-9228126 Fax: +39-040-9228122E-mail: [email protected]



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Laser technologies: A step forward for small and medium sized enterprises

Prepared by:Nicola Drago

Paolo VilloresiGraziano Bertogli

INTERNATIONAL CENTRE FOR SCIENCE AND HIGH TECHNOLOGY Trieste, 2008



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LASER TECHNOLOGIES: A STEP FORWARD FOR SMALL AND MEDIUM ENTERPRISESLaser technologiesLasers in the future: Perspectives for small and medium sized enterprises

ABSTRACT

This publication provides an overview of present and future laser technology applications for

industrial products manufacturing, e.g. metal and non-metal processing (cutting, marking,welding) and quality control. The target audience is small and medium sized enterprises (SMEs) inorder to raise their interest in these technologies, which could be complementary and, in certaincases, more profitable alternatives to conventional manufacturing technologies, due to their goodflexibility, quality of output and decreasing investment cost. This report is organised in two parts:

Laser technologies and Lasers in the future: Perspectives for small and medium enterprises

The first part of the report consists of a description of laser techniques, a review of some realmanufacturing cases in SMEs, and a review of some of the research and development (R&D)literature. The applications (cutting, marking, inspection, manual welding) were chosen based onthe following criteria: a) highest market share, as an indication of reliability; b) investment of lessthan €1 million; c) basic level competence required. These are suggestions only; there are many

other applications, and technology developments and improvements are continuing in aspects,such as efficiency, cooling and space requirements, speed, flexibility and price. Themanufacturing sector was chosen both because of the high added-value of laser technologies inthis sector, and its importance in the industrial bases of developing or transition economies.

The second part of the report focuses on laser technologies and applications, e.g. a)semiconductor high power lasers, b) continuous wave and pulsed fibre lasers, and c) solid statedisc and advanced CO2 lasers.

Furthermore, this publication examines some of the novel interaction mechanisms enabled bythese new technologies which provide opportunities for SMEs and entrepreneurs to undertakenovel processes.

Finally the input from the scientific research to the laser application market is reviewed along withdescriptions of applications with long term potential.

Laser technologies are a remarkable and a progressively more accessible option to obtain newproducts from a variety of materials (metal, plastic, leather, wood, paper and others) incompetitive conditions. However, in calculating the returns from investment in laser technologiesit must be remembered that lasers are not a panacea for every industrial process; although theymay have advantages over other technologies, learning will be required through experimentationwith configurations and materials, co-design between client and supplier to provide productenhancements, and formalisation of know-how to increase efficiency. Finally, SMEs will need tofind appropriate financing schemes for their investments.

This work is based on interviews with original equipment manufacturers (OEM), laser systemintegrators and manufacturing SMEs that utilise these technologies, combined with a review of some recent literature.For a more theoretical approach, the ICS Lectures on Industrial Applications of Lasers (2000,ISBN 92-1-106408-2) is recommended.



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Part 1: LASER TECHNOLOGIES



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SUMMARY

ACRONYMS .........................................................................................................................x1 INTRODUCTION TO LASER TECHNOLOGIES ............................................................ 12 SAFETY AND ENVIRONMENTAL PROTECTION......................................................... 43 METAL PRODUCTS .................................................................................................... 7

3.1 CUTTING............................................................................................................ 73.1.1 SMALL JEWELLERY AND DECORATION COMPONENTS.......................113.1.2 PARTS FOR LIGHT INDUSTRIAL EQUIPMENTS.....................................123.1.3 CUTTING FOR FABRICATION..................................................................14

3.2 MARKING ........................................................................................................163.2.1 A MARKING CASE ..................................................................................18

3.3 MANUAL LASER REFURBISHMENT OF DIES AND MOULDS.........................203.4 LASER WELDING PROCESS ...........................................................................22

4 NON-METAL APPLICATIONS: TEXTILE, GLASS AND OTHERS ................................264.1 A FASHION MARKING CASE...........................................................................294.2 TEXTILE PATCH PRODUCTION........................................................................324.3 CRYSTAL PROMOTIONAL GADGETS ..............................................................34

5 LASER INSPECTION.................................................................................................356 LOOKING AHEAD.....................................................................................................367 BIBLIOGRAPHY........................................................................................................378 SOURCES OF INFORMATION ..................................................................................409 ANNEX: ARTICLE SYNOPSIS....................................................................................41



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List of figures

Figure 1: laser components1

Figure 2: potential harms from portable devices5

Figure 3: laser on welding glove5

Figure 4: burn from partial 2kW CO2 laser reflection5

Figure 5: finger injury at the accident, after 10 days, after 21 days5

Figure 6: 2D cut on stainless steel sheet8

Figure 7: 3D cut on tube8

Figure 8: reduced scrape10

Figure 9: laser cut pendants for jewellery (on the right)11

Figure 10: small size laser cut components11

Figure 11: laser cut and engraved component11

Figure 12: lay out with 2 cutting machines12

Figure 13: laser cut stainless steel samples13

Figure 14: laser cut item13

Figure 15: lasing gas cylinders13

Figure 16: cutting gas storage13

Figure 17: 4-lasers lay-out14

Figure 18: fabricated frame from laser cut components15

Figure 19: laser cut profile in mild steel for fabrication15

Figure 20: fabrication job-shop lay-out15

Figure 21: marked metal coloured component17

Figure 22: marked metal component17

Figure 23: detailed picture marked on plate17

Figure 24: marked instrument manifold18

Figure 25: marking lay-out sketch19

Figure 26: welded item

20Figure 27: repaired mould

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Figure 28: welding in an inside edge

20Figure 29: cross section of filler deposit

20Figure 30: class I laser manual welder with open doors

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Figure 31: mould repair with a class IV manual laser welder21

Figure 32: Reflection coefficient, wavelength, materials22

Figure 33: temperature and welding section23

Figure 34: plasma generation23

Figure 35: speed, power and penetration23

Figure 36: influence factors23

Figure 37: lap seam welding scheme24

Figure 38: lap welding cross section24

Figure 39: T-joint schemes24

Figure 40: T-joint cross section24

Figure 41: butt weld schemes24

Figure 42: butt weld cross section24

Figure 43: pump components25

Figure 44: stainless steel container25

Figure 45: clothing accessories27

Figure 46: wood veneer27

Figure 47: decoration on denim28

Figure 48: embroidery cutting 28

Figure 49: graduated wear-effect on denim29

Figure 50: composed pictures29

Figure 51: marked golf with laser machining detail29

Figure 52: holes in technical tissue29

Figure 53: marked hearts on thick tissue30

Figure 54: cut and marked accessories30

Figure 55: textile marking lay-out30



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Figure 56: embroidery with laser cutting

32Figure 57: embroided item

32Figure 58: embroided and laser cut item

32

Figure 59: printed, cut and applied patches33

Figure 60: multicolour printed patch33

Figure 61: 3D engraved crystals34

Figure 62: 2D laser inspection equipment35



ACRONYMS xi

ACRONYMS

2D Two dimensions3D Three dimensionsABS Acrylonitrile butadiene styrene plasticCAD Computer Aided DesignCAM Computer Aided Manufacturing CNC Computer Numerical ControlCO Carbon MonoxideCO2 Carbon DioxideCW Continuous WaveHAZ Heat affected zoneHeNe Helium Neon laserLAN Local Area NetworkLASER Light Amplification by Stimulated Emission of RadiationLCD Liquid crystal displayLIS Laser Induced Super PlasticityMAG Metal Active GasMIG Metal Inert GasMPE Maximum Permissible ExposureN2 NitrogenNd:YAG Neodymium-doped Yttrium Aluminium GarnetOEM Original Equipment ManufacturersPC Personal computerPET Polyethylene terephthalate plasticPVC Polyvinyl Chloride plasticQC Quality ControlR&D Research and DevelopmentSME Small and Medium Enterprise/sSTENT A tube designed to be inserted into a vessel or passageway to

keep it open. E.g.: stents are inserted into narrowed coronaryarteries

TIB German National Library of Science and Technology(Technische Informationsbibliothek UniversitätbibliothekHannover, http://www.tib.uni-hannover.de/en/)

TIG Tungsten Inert GasUPS Uninterruptible Power Supply



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The laser in a nutshell

Lasers are light sources. The concept is very versatile; they can emitvisible, infrared or ultraviolet spectra; they can generate long as well asvery short pulses (pulsed lasers), or very powerful steady beams

(continuous-wave, or CW, lasers), which are focused using simpleelements such as lenses or concave mirrors in small micrometre-size

spots, or to propagate nearly parallel beams extending for severalkilometres (collimated beams). They differ from a fire, the sun or anordinary light-bulb in terms of the intrinsic light generating mechanismwhich radiates as a continuous repetition of spontaneous and disorderedprocesses, producing generally uniform illumination around them. The

generation of the light from lasers is by amplification of a well-ordered and single-frequency seed, which produces a very directed emission, which is single-coloured and coherent across the beam.The core of the light amplifier is the gain medium, which may be based on

a gas, liquid or solid medium, chosen for its optical properties. The gainmedium transfers to the optical beam the energy received from theexternal pump, the power supply. The amplification occurs within aresonator, usually consisting of a pair of aligned mirrors, with parallel

surfaces, in which the seed grows through multiple passages through the gain medium. The output beam slips off the resonator via one of themirrors which is semitransparent.Figure 1 depicts the principal components of a laser:

1. Active laser medium;2. Laser pumping energy;3. High reflector;

4. Output coupler;5. Laser beam

Figure 1: laser components

1 INTRODUCTION TO LASER TECHNOLOGIES

Innovation in manufacturing has a direct impact on the competitiveness of SMEs in terms of costs, but it also may enable new product design that would be not be achievable with the use of more conventional technologies. This is particularly true of laser technologies.

Following several decades of development and industrial use, lasers can now be considered to bestandard equipment, with wide commercial application and good reliability, comparable to othertried and tested industrial machinery. The producers of industrial lasers provide guarantees fortheir operation and specify standard maintenance programmes, which, in most cases, are lessdemanding than are required for mechanical equipment.

Clearly, there are more straightforward and affordable applications, such as cutting, marking, etc.,which can be considered to be ‘frontier’ solutions but whose development will take some time for



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them to be considered completely reliable. We have tried to select applications and technologiesthat are simple and accessible for SMEs embarking on investment in laser technology, and tohighlight ongoing developments.

It should be remembered that as SMEs’ experience in using lasers accumulates, it will becomeeasier to introduce new technologies on the shop floor, progressing from simple laser operations,such as marking, to cutting, and to more complex welding operations that facilitate the delivery of new products or services.

The laser process has many similarities with other manufacturing processes, in whichrelationships between customers and suppliers over design are very important.

Job shops or manufacturing facilities areas with short-time production planning, and product-linemanufacturers should choose their laser equipment taking account of the following points:□ are there alternative, more economic technologies?□ level of competence required for different processes (i.e. welding is normally more demanding

than cutting) and different materials (e.g. plastic or metal);

□ optimisation of operator time, especially in materials handling and tool change-out;□ optimal choice of components: laser manufacturer, laser model and type of automation,

specific to the application;□ availability of adequate infrastructure (gas, electricity, compressed air) and after-sales and

maintenance services;□ capacity balancing in order to avoid high investments producing bottlenecks in other

production phases.

Laser cutting and marking can usually be achieved using standardised machines; welding equipment is generally more specialised and needs adaptation to the customer’s application.SMEs requiring customised equipment may be able to obtain a full-package system from theOEM. Otherwise, they must use a systems integrator, i.e. a company that integrates standard

technologies in customised settings.

How lasers work

The laser beam interacts with materials in different ways depending on the type of target, its absorption and composition, the laser colour or wavelength, and theintensity of the laser beam.

The most common interactions are:□ thermal: the laser light is absorbed and converted into heat. The local temperature

rises rapidly. Depending on the material this may induce melting, vaporisation,combustion, degradation, surface hardening, etc.

□ photo-chemical: the light acts as a reagent and induces changes in the chemicalcomposition of the target material, or dissociation of molecules and disaggregationof compounds.

□ nonlinear: the high intensity of the laser pulses induces local vaporisation or defects in transparent materials, e.g. engraving on glass.

The industrial equipment has the characteristics and controls to allow precisematerial removal (cutting, drilling, marking), joining (welding and soldering), and

different kinds of thermal surface modifications (hardening, alloying, cladding).



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Laser market

Here we are interested in materials processing applications which use laser sourcesthat are different from the lasers used for telecommunication and optical storage(e.g. optical fibre telecommunication, DVD-CD writers/readers, bar-code readers,etc.). These latter are very low power, and cannot be used in manufacturing.The global market for non-telecommunications lasers in 2007 was expected to

exceed US$6 billion, with a positive trend for volume and decreasing trend for prices.The major industrial laser market players reported sales increases of 12%-18% in2006 compared to 2005. Materials processing applications represent the vastmajority of these laser sales. Concerning types of lasers, the 2007 market share was:

solid state lamp-pumped, CO2 flowing, excimer, solid state diode-pumped, fibre, CO2-

sealed, other.

Laser types

Below is a list of lasers in general industrial applications.

□ Gas lasers: are the most widespread industrial lasers. They are based on a gaseous gain medium, which is energised to produce the light amplificationthrough an electrical discharge. The most common application in this class is thecarbon dioxide, or CO2 laser, which is used for materials processing and has thebiggest market share, although other types (HeNe, Argon-ion, CO) are alsoimportant. The CO2 laser emits infrared radiation at a wavelength of 10.6micrometres, and can be produced from power outputs of a few tens of Watts (W)to a few tens of kiloWatts (kW);

□ In solid state lasers: the gain medium is a doped crystal or glass, pumped by strong flashlights or diode lasers. The most common type is the Nd:YAG laser, from theNeodymium-doped yttrium aluminium garnet (YAG), whose wavelength is 1.06

micrometres, in the near-infrared, and is easily deliverable by fibre optic;□ FibreFibre lasers: the gain medium is a piece of optical fibrefibre doped with

elements such as erbium or ytterbium. They require a diode laser as a pump,injected into the gain medium. The infrared beam is of very good quality and their output power has reached the kW range, and is naturally delivered by a fibrefibre.This type of laser is the most recent development and is undergoing rapid growth.

□ Semiconductor – or diode – high-power lasers: these are very important sources inthe near infrared, which may reach kW output. They are based on telecom diodelaser technology, but are a thousand-fold more powerful while maintaining a 1centimetre size. The beam is of lower quality than from other sources, and requiresadvanced beam shaping optics to be launched in fibrefibres. Their initial and still

widespread use is for optical pumps in Nd:YAG lasers, as beneficial alternatives tolamps. They are also used for low power applications, such as miniature welding,for thermal treatment of metals using large spots which direct more sources,reaching multi-kWs, and for welding plastics.

□ Chemical lasers: are powered by chemical reaction. Examples are hydrogenfluoride or deuterium fluoride; they are only used where there is no electricity available.

□ Excimer lasers: are very intense sources of ultraviolet light, used in medicine andlithography, and are based on a gaseous gain medium strongly pumped by an

electron beam.



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2 SAFETY AND ENVIRONMENTAL PROTECTION

Safety cannot be emphasised too much. Users of laser technologies must be aware of two mainissues for which solutions are widely available: the risks to operators’ eyes and skin, and theemissions, which can affect the environment and threaten the health of operators.

In terms of protection, SMEs must take account of the following issues in order to introducesafety procedures to protect personnel and the environment:

□ Laser class: this is clearly specified in the equipment documentation (brochure, manuals) andon the equipment itself and is classified according to the international laser safety standardIEC 60825-1. The classification can range from I the safest, to IV the most hazardous. Adescription of these classifications is included at the end of this chapter.

□ Eyewear and wavelength: Operators must wear protective eyewear - ‘laser goggles’ - according to the wavelength and laser class. Guidelines can be found in the national standards system orin the European norm EN207 and EN208 or US norms ANSI Z136.1-2-3-5-6(http://www.laserinstitute.org/store/ANSI/106A). Even exposure to relatively low power laserscan be dangerous. Near-infrared laser radiation of 400-1,400nm wavelength may causeheating of the retina, cataracts or burn injuries, which can occur without pain to the operator orany immediate effect on sight. (A popping or clicking noise from the eyeball indicates retinaldamage, which could result in permanent blind spots).

□ Skin burns: exposure to high power beams at any wavelength can result in skin burns. Althoughrecovery will be complete, there will be short term pain and discomfort. Focused beams cancause burns, and deep cauterised or bleeding holes or cuts.

□ Air contaminants: suitable capture devices must be installed to reduce the health andenvironmental hazards from laser processing. Devices such as table exhaust systems, working head integrated systems, total enclosures, and filters can be provided by the OEM or found onthe market. Due to their thermal character and the variety of applications and materials (metal,

wood, plastic, and others), laser processing can emit a complexity of air contaminants that maybe malodorous and have serious side effects for humans as 40%-60% of these contaminantssettle in the alveoli of the lungs. Certain plastics (PVC, PET, ABS, etc.) applications generatedioxins; wood can generate flammable components and dust; chrome tanned crusts candisperse heavy metal particles; and metals can generate metallic particles. The highestemission rates are associated with laser cutting (>100mg/s); these levels may be 10 to 100times lower for material removal or marking. Proper fume exhaustion devices must be installedin production units.

□ Proper working conditions: laser operators must be ensured safe and comfortable working conditions, and especially those working on higher classes of lasers or portable laserequipment. This may include proper enclosures, wavelength specific eyewear, protectiveclothing, safety interlocks, properly displayed safety information on laser radiation, warning

lights, plans of the laser sources in the building or area, in addition to standard operating procedures and suitable education and training. Such precautions will enhance both safety andproductivity.



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Figure 2: Potential harms from

portable devices

Figure 3: Laser on welding glove

Figure 4: Burn from partial 2kW

CO2 laser reflection

Figure 5: Finger injury at time of

the accident, after 10 days, after

21 days

Exporting lasers

Although commercial laser systems are usually licensed, there are alsoexport controls to which lasers are subject, which limit the shipment of products with potential military application, from Wassenar 1 to non-Wassenar countries. Initial developments in lasers were and still areconnected to weaponry. Their control is based on quantifiable parameters

such as power, wavelength, and overall efficiency and distinguishesbetween lasers that can be freely exported and lasers that can only beexported under licence, which include continuous wave CW, pulsed, andtuneable lasers.1 The participating Wassenar countries are: Argentina, Australia, Austria, Belgium,

Bulgaria, Canada, Croatia, Czech Republic, Denmark, Estonia, Finland, France, Germany,Greece, Hungary, Ireland, Italy, Japan, Latvia, Lithuania, Luxembourg, Malta,Netherlands, New Zealand, Norway, Poland, Portugal, Republic of Korea, Romania,Russian Federation, Slovakia, Slovenia, South Africa, Spain, Sweden, Switzerland, Turkey,Ukraine, United Kingdom, United States of America. Information is available at the

Wassenaar Arrangement website http://www.wassenaar.org/



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LASER CLASSES

(from Wikipedia: http://en.wikipedia.org/wiki/Laser_safety):

class I

A class 1 laser is safe for use under all reasonably-anticipated

conditions of use; in other words, it is not expected that the maximum

permissible exposure (MPE) can be exceeded. This class may includelasers of a higher class whose beams are confined within a suitable

enclosure so that access to laser radiation is physically prevented.

class IM

Class 1M lasers produce large-diameter beams, or beams that are

divergent. The MPE for a Class 1M laser cannot normally be exceeded

unless focusing or imaging optics are used to narrow the beam. If the

beam is refocused, the hazard of Class 1M lasers may be increased and

the product class may be changed.

class II

A Class 2 laser emits in the visible region. It is presumed that the blink

reflex will be sufficient to prevent damaging exposure, although

intentional, prolonged viewing may be dangerous.

class IIM

A Class IIM laser emits in the visible region in the form of a large

diameter or divergent beam. It is presumed that the human blink reflex

will be sufficient to prevent damaging exposure, but if the beam is

focused, damaging levels of radiation may be reached and may lead to

a reclassification of the laser.

class IIIR

A Class 3R laser is a continuous wave laser which may produce up to

five times the emission limit for Class 1 or class 2 lasers. Although theMPE can be exceeded, the risk of injury is low. The laser can produce

no more than 5 mW in the visible region.

class IIIB

A class 3B laser produces light of intensity such that the MPE for eye

exposure may be exceeded and direct viewing of the beam is

potentially serious. Diffuse reflections (i.e., that which is scattered

from a diffusing surface) should not be hazardous. CW emission from

such lasers at wavelengths above 315 nm must not exceed 0.5 watts.

class IV

Class 4 lasers are of high power (typically more than 500 mW if CW,

or 10 J/cm² if pulsed). These are hazardous to view at all times, maycause devastating and permanent eye damage, may have sufficient

energy to ignite materials, and may cause significant skin damage.

Exposure of the eye or skin to both the direct laser beam and to

scattered beams, even those produced by reflection from diffusing

surfaces, must be avoided at all times. In addition, they may pose a fire

risk and may generate hazardous fumes.



CUTTING 7

3 METAL PRODUCTS

3.1 CUTTING

OVERVIEW

Laser cutting is the cutting of solid materials using a focused laser beam. It is by far the most

common application of industrial laser technologies and also one of the most standardised. Thematerials to which it can be applied include mild steel, stainless steel, aluminium, alloy metals,reflective metals such as copper and brass, glass, plastic, leather, wood, and in a wide range of thicknesses. Most materials can be cut by a laser.

Laser cutting represents a step forward in product design, and especially in relation to the valuethat is added to products requiring complex profiles or holes. In these cases, laser use isprofitable even for small production runs. The characteristics of commercial lasers make themvery flexible: no tooling, no mechanical contact, little inertia, very small cut width and restrictedthermally-affected zone, wide range of thicknesses of good finishing cutting, user friendly CNC(computer numeric control) programming and interface to CAD (computer aided design), minimalmaintenance. However, the full benefits of their exploitation can only be achieved throughexperience in use and the integration of design and manufacturing, i.e. design synergy betweenclient and supplier.

In the case of sheet metalworking, laser systems often substitute for the more conventionalguillotine shears and punching machines and avoid the use of ad-hoc tooling for curved profiles.Lasers can cut down on 90% or more of a job-shop production. However, the entrepreneur mustbe certain that working and safety conditions are met (see chapter Plant and Equipment), andthat adequate servicing facilities are available in the area and should ensure whether the productcould be produced more economically with other technologies such as ad hoc dies in automaticmachines in the case of long runs, or oxygen lance or plasma cuts in the case of lesscomplicated/lower finish work.

Reliable technologies (CO2 was introduced in the 1960s, Nd:YAG in the 1970s), programmable

logics, CAD/CAM nesting, adaptive diagnostic systems that monitor the region affected by thelaser beam, and automation, extend and ease the cutting jobs undertaken by SMEs, which canexploit the system on a three-shift/day basis, 6,000 hours/year, will not be dependent on theconstant presence of an operator or on highly skilled operators to obtain the desired flexibility,cutting profiles and quality made viable by the use of lasers.

The cut can be executed in two dimensions (2D), for instance on metal sheets, or in threedimensions (3D) in the case of components that need to be cut in width, length and height suchas tubes.



CUTTING 8

Figure 6: 2D cut on stainless

steel sheet

Figure 7: 3D cut on tube

In principle, lasers can cut any complicated profile and a range of organic and inorganicmaterials, which makes them one of the most flexible manufacturing technologies available, andhas brought a shift in product design.

SME operators usually consider laser applications to be most appropriate for high value-addedproducts, i.e. materials whose profiles and finishes justify investment in an expensive, thoughreliable, technology. SMEs tend to purchase the highest power generation available in the market.Many invest in an additional laser machine before the end of the cycle of depreciation of anexisting one to enable specialisation by material.

Depending on the application, SMEs can find commercial equipment with three to four axesmovements for 2D cutting or five to six axes for 3D cutting, whose beams can be delivered byrobot systems in the case of fibre lasers and also CO2 systems with more complex optic systemswhich are normally only justified in high value added and capital intensive plants. Motion can bevia flying optics, sliding worktables or a hybrid solution.

Different materials may require different technologies:

□ CO2 lasers are especially indicated for mild steel, stainless steel, iron, nickel, tin, lead, PVC,epoxy, leather, wood, rubber, wool, cotton, acrylics, polyethylene, polycarbonate. In spite of their vast range of applications based on beam quality, low cost, and reliability, CO2 laserscannot be delivered by fibre optics because of their wavelength, They are thus not easilymanipulated by robots;

□ Nd:YAG lasers, whether lamp or diode pumped, are indicated for aluminium, copper, brass,platinum, gold, silver, hastelloy, silicon nitrides, aluminium oxides, boron nitrides,polycrystalline diamond, pyrographite, titanium, tantalum, zirconium, molybdenum, tungsten,chrome, glass, quartz, asbestos, mica, and natural stones. Because of its wavelength, theNd:YAG laser can be transmitted through fibre optic and is suitable for robotic manipulation;

□ Ytterbium fibre lasers are another technology that has recently come onto the market. Theircurrent high price is counterbalanced by their greater efficiency (up to 30% at the time of thepublication), higher output power (commercial models up to 10kW or even scalable to 50 kW,vs 4kW-6kW of CO2 and Nd:YAG), very high beam quality, simpler cooling (tap water), longerpumping diode duration (25,000 vs 10,000 hours) and consequent lower maintenance costs,which result in lower per hour operating costs, greater portability and novel application.

Ytterbium fibre lasers can be used to cut mild steel, stainless steel, titanium alloy, aluminiumalloy, galvanised steel, nitinol, inconel, and plastics.

□ Disc lasers are another recent technology, which has the same cutting applications as Nd:YAG,but at higher power densities and wall-plug efficiency (15% at the time of the publication), thusenabling faster and deeper cutting.

In 2006, the fibre and disc lasers had a +45% sales trend world wide compared to 1%-5% of themore traditional CO2 and Nd:YAG, although the volume of sales of these latter two is 14 timeshigher. The diffusion of fibre and disc lasers may erode the market shares of the more‘conventional’ laser technologies as investment and running costs (especially linked to diode



CUTTING 9

duration and maintenance) decrease and facilities costs in the industrial environment comedown.

PLANT AND EQUIPMENT

Laser cutting equipment requires a series of working conditions to be fulfilled in order to maintainreliability. In the reference case of a world standard 3.2kW CO2 machine cutting 3,000mm x1,500mm sheets up to 20mm in mild steel, 12mm in stainless steel or 8mm in aluminium, thefollowing conditions would apply:

□ Electricity should be stable at 400V ± 10V nominal. Power consumption ranges between 27kWand 53kW and the electric installations should bear 85kVA. In case of low stability,interruptions or shading, the entrepreneur should consult with the laser OEM about whether itis reasonable to use stabilisers, continuity groups, generators and/or switches from the grid topreserve the equipment. In fact, interruptions may cause higher scrapes because of qualityproblems and equipment damage.

□ Pure lasing and cutting gases should be available in adequate quantities, certified andreasonably priced. Lasing gases could be delivered in batches of several cylinders while cutting

gases could be stocked in large pressure tanks (e.g. 5,000 litres) either owned or leased.Impure gases or lack of gases can greatly reduce cutting speeds and maximum thicknesses. Inthe case of high power CO2 cutting the following purity specifications apply:

GAS GRADE PURITY

CO2 4.8 99.998%

N2 5.0 99.9990%

He 4.6 99.996%

O2 3.5 99.95%

□ Compressed air, substituting N2, should be of hospital quality purity. Lubricant polluted

compressed air could damage equipment;□ Cooling water should be demineralised with conductivity lower then 10-5 μsiemens/cm for CO2

lasers (fibre lasers require tap water). Higher cooling options may be selected in the case of tropical temperatures;

□ Although a deep basement is not required, a flat stable base is required to maintain thecalibration positioning. For reference, calculate an approximate applied force of 27,000N forthe machine and 7,000N for the loading automation; additional criteria apply in the case of faster equipment (e.g. with linear motors);

□ Adequate working space should be assigned to loading operations, off-loading, safety lightbarriers and materials handling. For reference: with the exception of materials handling runways, the surface required should be approximately 9m x 11m or, if a loading automation is

installed, 11 m x 13 m;

□ Safety devices for the protection of operators and the environment. Photovoltaic (PV) barriersto prevent accidents are normally provided with the equipment; exhaust and dust filtrationmust be carefully selected because the dust particles from these operations can be inhaled;

□ A personal computer (PC) and nesting/programming software are recommended to enableprocess optimisation and cost reduction. Appropriate production planning, mixing of differentorders, and nesting software can reduce scrape material to less than 10% resulting insignificant cost reductions.



CUTTING 10

Figure 8: Reduced scrape

The investment required for a cutting system depends on the type of technology, equipmentstandardisation, and automation. In addition, the entrepreneur should evaluate the Incotermsand plant costs involved in housing this equipment, which will vary from country to country. At thetime of the writing, as a rule of thumb, a maximum of €500,000 would be needed for a medium-high cutting station: €300,000 for the complete cutting system based on a 3.2kW CO2 lasersource (for 3,000mm x 1,500mm plates), €20,000 for programming and nesting software and€120,000 for loading automations if requested. Laser cutting SMEs tend to purchase the highestpower generation available in the market; however, such equipment may have higher costs (forreference the most recent 6kW CO2 equipment and loading automation at 2008 prices costsapproximately €1 million), which enable state-of-the-art performance provided the appropriateworking environment, experience and maintenance are available. In principle, it is not necessaryto have the highest power and SMEs should evaluate the level of power appropriate to theirprojected production.

For CO2-cutting running costs, commercial OEMs can estimate for customers the cost of differentapplications (materials, thicknesses). The following are provided as a guide but will vary fromcountry to country and will also depend on the duty cycle:1

□ Electricity: an average of 70-80kW per machine in real terms;

□ Gas: lasing and cutting gases are supplied by a limited number of companies, and prices arevolatile. A rough estimate of lasing gas consumption may be in the range 1, 6, and 13litres/hour respectively for CO2, nitrogen and helium, and 500-2,000 litres/hour for cutting gases (CO2, nitrogen) in high power systems; mid- and low-power lasers may have a much loweror even no consumption, as in the case of sealed tube lasers, available up to about 500W.

□ Maintenance: laser equipment tends to be reliable; however, good maintenance maintainscompetitiveness because down-time and spare-parts are expensive. In the case of CO2

equipment, the entrepreneur may budget 1 day/month for preventive maintenance and, inEurope, €10,000-25,000 in consumables and manpower/year, proportional to machineperformance. Items that need maintenance are filters, lenses (once or twice a year if the

machine is used properly), final stage valves, and telescopic covers in the case of fastermachines. Cut thicknesses and performances progressively decrease with longer maintenanceintervals.

□ Personnel for up/off-loading and programming;

□ Depreciation: depending on the allowed rates;

□ Compressed air

□ Raw materials (if applicable).

1i.e. the time of laser-on, which may vary from 15-80%, and the hours of operation, normally 2,000-4,000 hours,

but could reach 6,000 hours, based on 20 hours/day, 5 days/week, and 10 hours/day 1 day/week on a 12 month

basis.



CUTTING 11

CUTTING EXPERIENCES

This chapter describes the products and plants from three family-owned job-shops with short orvery short production planning (4-30 days): small products frequently used for jewellery, stainlesssteel components for equipment fabrication, and thick mild steel for buildings and equipment.

3.1.1 SMALL JEWELLERY AND DECORATIVE COMPONENTS

A 15-employee company registered in 2000 operates a 1,400m2 plant with two CO2 laser cutting machines and a 100W Nd:YAG diode pumped laser marking machine, to produce flatcomponents for jewellery, decorative items and food equipment, with a production planning timeof up to 4 days.

The cutting machines have 2kW and 3kW output power and are generally used respectively to cut3,000mm x 1,500mm and 4,000mm x 2,000mm stainless steel plates normally in 2mmthickness, and less frequently because of market specialisation, exotic materials or thicknessesup to 20mm.

The laser permits flexibility in terms of profiles, speed and quality, unachievable with traditionaltechnologies. Accurate selection of cutting speed allows adequate finishing, possibly avoiding further grinding, brushing or polishing of the cut surfaces.

Figure 9: Laser cut pendants for

jewellery (on the right)

Figure 10: small size laser cut

components

After cutting, many items are marked with the Nd:YAG machine, which has a four-positionindexing table, to add further features or traceability.

Figure 11: Laser cut and engraved component

Of the 15 employees, 9 are involved in production and 6 cover the engineering, commercial and

administrative functions. The cutting laser operator, the marking operator and the programmerhave job-shop and technological expertise. They have attended OEM courses on safety andmachine working and inhouse courses on production organisation. No formal engineering education is required for their jobs.



CUTTING 12

Figure 12 depicts the job-shop lay-out:

Figure 12: Lay out with two cutting machines

3.1.2 PARTS FOR LIGHT INDUSTRIAL EQUIPMENT

The production of metal components for light industrial equipment manufacturers is the dailyactivity of a 20 employee SME that operates four different pieces of CO2 laser equipment cutting 3,000mm x 1,500mm plates, in addition to other traditional sheet metalworking machines andwelding workstations.

The long tradition in the sector began in the late 1960s based on punching machines and

guillotine shears, then CNC systems and, in 1989, the first laser cutting equipment. Theexperience and the product specifications steered the company to specialise their laserequipment according to materials and thicknesses. This required 30 day work plans. Thecompany uses the laser equipment only 2,200 hours/year per station, and operates 1 shift/day.

Being a supplier of OEM sub components, the SME stresses that a form of co-design betweenclient and supplier or mutual education to design for laser manufacturing is necessary in order forthe product to exploit the potentialities of the technology.

The products consist of cut, bent and welded metal sheets in mild steel up to 25mm, in stainlesssteel to a maximum thickness of 15mm, in aluminium at 6mm, and in brass at 4mm, ready topaint. Cutting is also done on bent components; machining is outsourced. Laser machines cut anaverage 90% of all processed material, whether laser intensive, such as small parts, or materials

intensive such as thick plates, while the remaining rectilinear profiles are cut by CNC punching machines.

Offices and servicesOffices and services

Up and off loading

automation

4,000mm x 2,000mm laser

3kW cutting machine and auxiliaries, including safety

devices3,000mm x 1,500mm

2kW laser cuttingmachine including

auxiliaries and safety

devices

Finished

products

area

Marking

machine

Raw material (metal sheets) warehouse

Way out

Door



CUTTING 13

Figure 13: laser cut stainless

steel samples

Figure 14: laser cut item

The company has always purchased the latest and most powerful CO2 models, in order to achievethe highest speeds, thicknesses and flexibility and, at the time of the interviews, operated a2.6kW, a 3kW, a 4kW and a 5kW machine, this last connected to an automated warehouse andloading system. The possibility for using different equipment in parallel enables knowledge to beaccumulated in different materials and processes.

Because of the high volume of material being processed and the intensiveness of laser cutting,the company utilises cylinders for lasing gases, packs of cylinders for cutting CO2 and a 5,000litre nitrogen tank for cutting, all these costs being included in the laser evaluation.

Figure 15: lasing gas cylinders Figure 16: cutting gas storage

The company relies on two high-school qualified mechanical technicians for nesting, programming and minor problem solving and on four specialised workers for up/off-loading, programme recall,and minor calibration procedures.



CUTTING 14

Figure 17 depicts the job-shop lay-out:

3.1.3 CUTTING FOR FABRICATION

This is a 17-employee job-shop with experience gained over 10 years, from operating three lasermachines, which uses a single standard 3kW CO2 machine to cut 90% of the metal needed tofeed conventional bending and welding workstations. Production focuses on mild steel andstainless steel which is transformed from raw plates into components for equipment ranging fromindustrial washing to injection moulding, naval interior wall panels and other shaped profiles. Thecompany cuts some 15 tons of metal/month and is now operating on a 15-day schedulecompared to the previous 60-day schedule because global supply chains have steered theproduction towards less repeatable, more complicated, higher value added components withstretched lead times.

The introduction of laser technology followed the use of more traditional guillotine shears andsquares and brought a change in design for manufacturing, to exploit the potential of lasers fornew product design.

Mild steel is cut in thicknesses of between 0.8mm and 20mm while stainless steel plates rangefrom 0.8mm up to 12mm. Key issues for the company are machine reliability and finishing, whichis inversely proportional to cutting speeds. As a reference, the complete cycle for a profiled plate700mm x 350mm x 6mm, such as that depicted in Figure 19: laser cut profile in mild steel forfabrication, is approximately 2 minutes.

Legend:1. 2.6kW2. 3kW3. Automated warehouse4. 5kW5. 4kW6. N2 storage

1 2 4 53

Semi-finished

warehouse for

bending

raw material(metal sheets)

warehouse Finished

productswarehouse

Finished products

warehouse

Offices

Stainless steel bending

equipments and sheet metal

warehouse

Punching, shears

equipments and sheet

metal warehouse

waterjet

Welding

workstations

and welding

robot

6



CUTTING 15

Figure 18: fabricated frame from laser

cut components

Figure 19: laser cut profile in mild steel

for fabrication

The company has four managers responsible for commercial deals, purchasing, productionplanning and control, an administration staff, six welders, four punch and shearing machineoperators, and three laser operators. The work division is flexible to enable the company to cope

with several assignments.

The laser staff includes a designer responsible for nesting, programming and bills of materials, alaser-machine operator who monitors programmes and production, and an off-loading operatorassisted by automated up-loading which extends lasing-times to more than 10 hours per day. Thelaser team has extensive job-shop experience, familiarity with and interest in technology, and hasbeen trained in a one-week OEM course; none of the team has any formal engineering education.

Figure 21 depicts the various machines in the 2.000 m2 plant:

Figure 20: Fabrication job-shop lay-out

2

3

1

Metal sheet

warehouse

Bars and profiles

warehouse

Semi-

finished

deposit

for shears

s h e a r s

b e n d i n g

p u n c h

i n g

b e n d i n g

b e n d i n g

b e n d i n g

Welding workstations

Q C c o n

t r o l a n d f i n i s h e d p r o d u c t s

w a r e h o

u s e

Laser items:

1. Up-loading

automation;

2. CO2 laser

cutting

machine;

3. Off-loading

area and cut-

item buffer



MARKING 16

3.2 MARKING

OVERVIEW

Laser marking is a relatively low cost operation. It is used to permanently inscribe on the surfacesof materials, graphic information, such as bar codes, alphanumerical tags, indicator lines in

gauges, drawings, etc., using a laser beam. Its use to allow product traceability or provideinformation is growing. Laser marking can be a substitute for mechanical embossing, engraving,or printing processes.

Laser marking permanently modifies the surface of a material. The laser emits short pulses (10-200 nanoseconds) which make a disturbance (a single spot) on the surface that is visible whenilluminated. A single spot is of small diameter, in the range 30-500 micrometers, and can becomethe element of a letter, a drawing or a graphic. The repetition of laser pulses is quite high, 10-100kHz, and the position of the mark is directed by a pair of mirrors actuated by a computercontrolled driver.

In standard applications, the material surface is ablated by the laser beam when it reaches anenergy density above the ablation threshold of the material: a small volume of the material is

removed in vaporised state. A repetition of laser irradiation on a single spot results in aprogressive engraving.

Photochemically induced marking involves a permanent colour change, obtained by exceeding the degradation threshold temperature; the process is quieter and produces fewer pollutants.However, ablation is normally faster and deeper than photochemical induced marking.

It is possible to utilise different types of marking lasers depending on the materials and themarking rate required. Solid state laser, such as Nd:YAG lasers, are best for marking metals anddark plastics, CO2 systems can be used to mark ceramics, transparent and organic materials. Inthe case of Nd:YAG lasers, a pump source using diode-laser or flash-lamp is required, depending on the power. The diode-pumping technology, which is a more recent technology, involves smallerequipment, lower maintenance costs, smaller power requirements, and less complicated cooling

(air instead of water), but is usually limited to use with sources of about 20W of output power.CO2 lasers differ in terms of spot sizes which are larger. They are recommended for a variety of relatively soft materials such as wood and plastic.

Marking speeds are proportionally slower when higher resolution is needed, and depending onthe characteristics of the material being engraved. The OEM or resellers can advise on whichequipment is best for each application.



MARKING 17

PERSONNEL AND EQUIPMENT

Usually one person can operate and program a laser marking system. This individual would needsome background in shop operations and some capabilities in the use of CNC systems. OEMsnormally provide programming and safety training as a package with the marking system.Alternatively, an engineer could program the marking instructions and production staff could

operate the equipment following the instructions provided.

Depending on the manufacturer and the model, laser marking machines can process itemsweighing up to 100kg, and up to 1,000mm x 400mm x 750mm in dimension, which would covera range of products including items of jewellery to bigger metal items or a series of smaller itemsproperly aligned on a pallet.

Figure 21: marked metal coloured

component

Figure 22: marked metal component

Depending on production needs, the marking laser can be integrated into an automatedprocessing line in the case of high volume applications, or can be a standalone workstation. Astandalone laser marking machine is quite small; a standard model requires a space of approximately 1,000mm x 1,000mm÷1,500 mm x 2,000 mm (height) and foundations capableof bearing 500kg weight or 800kg for larger three-phase equipment.

In order to optimise operations, the system should be connected to a fume exhauster and filtering device in compliance with the safety regulations and positioned in an easy-to-load place withaccessible and well organised feeding and stocking facilities.

The marking process is programmable via user-friendly software and can be controlled eitherlocally by the operator or remotely by an engineer across the company LAN.

The most common two-phase systems consume less then 2kW power and deliver beam powerranging from 5W to 150W; three phase systems may require up to 5kW.

In terms of investment, a mid size, standalone marking system could be in the range €50,000-100,000 including the software and operator training in programming, use and safety, from avariety of marking system manufacturers. Companies also need to consider investment in a

Figure 23: Detailed picture marked on

plate



MARKING 18

vacuum system, modifications to shop floor lay-out to house the new operation and perhapsinstallation of a local area network (LAN) in the job-shop.

Running costs will include maintenance (mainly filter cleaning, according to the load, andminimum annual laser maintenance), electricity costs, equipment depreciation and the cost of the loan (if any) for purchasing the system. Not all SMEs have a cost-accounting administration,and most estimate hourly costs with margins to cover all the above items.

A ballpark laser marking costing might be:

€88,300 + Hypothetical equipment price including softwareand training

€11,700 = Interests (with a 5 years loan at 5% interest rate)

€100,000 / Total equipment cost

5 years / Years of depreciation

€20,000 + Yearly cost of asset

€2,000 / Yearly quote of pumping diode substitution(€10,000, 12.000 working hours, 2,400 working hours/year)

2,000 hours = One operator’s yearly working time

€11 Equipment cost

In addition to this, the entrepreneur should consider the following

(depending on the Country) + Electricity cost

(depending on the OEMand the metals)

+ Maintenance cost

(depending on the Country

and the Company)

= Overhead costs

Total €/hour Reference hourly cost used in budget calculations

3.2.1 MARKING – A CASE STUDY

In the case analysed, the production of components for the petro-chemical industry requires lasermarking before assembly. The case study company is part of a large diversified group thatproduces industrial hoses and machined components and employs 22 highly qualified people.Operations include order processing, production planning and engineering and purchasing; mostof the company’s employees are engaged in the manufacturing and assembly areas, where themarking system is installed.

There are seven product lines (valves and manifolds, pressure pneumatic transmitters,pneumatic/electronic level transmitters, air filter regulators and vibration switches) and morethan 500 models in a list of about 5,000 components composed of stainless steel or exoticmaterials, such as titanium, hastelloy, incalloy 825, inconel 625, monel 400 and others, whichare finally sold in the international market.

Figure 24: Marked

instrument manifold



MARKING 19

The marking operation involves a small percentage (5%) of the production, and is used to providetraceability of components or to display information permanently.

A diode pumped Nd:YAG 2kW machine is operated by a trained worker 8-10 hours/day, 6days/week. This operator and two other workers run the whole quality control (QC)-testing,marking, assembly and shipment processes. Marking requires loading of up to six aligned itemsand then pushing the start button, which automatically closes a sliding door which is a safetyfeature. Processing takes between 6-10 seconds per item for photochemical marking and afurther 2-3 seconds for the engraving cycle after which the items are offloaded. The marking process could be made more sophisticated by the addition of automated warehouse, materialshandling, loading and off-loading systems.

Figure 25: Marking lay-out sketch

C o m

p o n e n t s r e a d y f o r Q C

C o m

p o n e n t s r e a d y f o r Q C

C o m

p o n e n t s r e a d y f o r m a r k i n g

C o m

p o n e n t s r e a d y f o r m a r k i n g

Marking laser

Vacuum and filtering unit

S t o r a e o f m a r k e d c o m

o n

e n t s b e f o r e

Q C t e s t b e n c h e s

Q C t e s t b e n c h e s

Assembly, packaging and shipment area



MANUAL LASER REFURBISHMENT OF DIES AND MOULDS 20

3.3 MANUAL LASER REFURBISHMENT OF DIES AND MOULDS

OVERVIEW

Cracked moulds can cause problems in plastic injection moulding or metal die casting plants.They can be repaired using traditional welding technologies, such as Tungsten Inert Gas (TIG), orby deposit welding using by Nd:YAG lasers2 with a narrow filler wire; these repairs can be

accomplished in-house or outsourced to job-shops. Laser and TIG can be considered to becomplementary because of their different performance and hourly costs, which are higher forlaser due to the higher initial investment, but have some benefits over TIG. For example:

□ they do not require the mould/die to be heated before welding, which shortens the processing cycle;

□ the heat affected zone (HAZ) is reduced because the sublimation and the cooling speeds arehigh;

□ it is possible to weld in confined spaces (cavities, interfering contours);

□ the post processing finishing takes less time due to the laser’s finer welds.

THE PRODUCT

Laser deposit welding can be used to repair polymer injection moulds, pressure dies, punching and cutting tools, forging dies and blowing mould tools.

Figure 26: welded item Figure 27: repaired mould

Figure 28: welding in an inside edge

Figure 29: cross section of filler deposit

Commercial systems can handle base materials of up to 64 Rockwell Hardness (HRC) anddimensions of 200mm x 200mm x 200mm to 500mm in length if the class I shields are open,which provides a much bigger working area (class IV). In the case of bigger work-pieces (e.g.1,700mm x 1,800mm), it is possible to purchase a laser system comprising the laser source, abasement, a three axes mechanics and a laser head with no protective enclosure. In working areas (class IV), operators are required to wear laser-specific eye protection (goggles) suited tothe wavelength applying; no other personnel should be within the radius of the laser beamdispersion. Moulds for class I machines can exceed 300kg.

2 A video of mould reparation can be found at

http://www.sitec.lecco.polimi.it/SitoSITEC_IT/video/powerweldHQ.htm



MANUAL LASER REFURBISHMENT OF DIES AND MOULDS 21

EQUIPMENT AND PERSONNEL

Welding equipment used to repair moulds and dies is normally manual, using Nd:YAG lasersources of approximately 80-120W average output. Depending on the mould dimension, theshop-floor may decide to use class I systems with enclosures for small items, or class IV systemswithout enclosures for bigger items. In the latter case the operator must wear laser gogglessuitable for Nd:YAG wavelengths of 1.064nm. Manual welding without filler wire can also beoperated.

Figure 30: class I laser manual

welder with open doorsFigure 31: mould repair with a

class IV manual laser welder

Operators would normally sit: in front of the enclosed work table or piece, inspecting the welding area through a LCD screen or a magnifier, and controlling operations with a joystick. The operatorcan command a motorised focus adjustment, a temporal pulse-shaping to induce post welding annealing or can store a particular contour for repeat use (repeatability in standard 2D actuatorsmay be as low as 20μm). CAD drawings can be loaded in a variety of formats from thosedeveloped for CNC. Due to the possibility to use very thin filler wires (ø 100μm÷400μm) and tothe laser weld characteristics, post processing takes much less than with TIG.

In terms of the plant conditions required to host the welding equipment, equipment with fullenclosure, in safety class I, would occupy approximately 1,000mm x 1,000mm x 2,000mm andweigh in excess of 200kg. A larger station that is open and in safety class IV, would require at

least 1,000mm x 2,000mm x 2,000mm and a load bearing base capable of 400kg plus theweight of the workpiece. Normally this equipment uses a three-phase energy supply at 400V witha recommended continuity group, and requires a deionised water cooling loop for the lasersource.

For the applications described above, the welding station should be installed on a ground floor.Insulation from vibration, for example, from traffic, railways, etc. is important; any strong vibrationcould affect the precision of the process.

New manual laser welders that can be used for mould repairs cost in the range of €30,000-80,000 at the time of the interviews. Among the running costs the main items are related topower use (about 1.6kW for a medium station), maintenance and filler wire - estimated at€1/hour and €200 for a 50m wire with ø0,8mm÷1.2mm, respectively). The main consumables

include laser-pumping lamps (€250/500÷1,000 hours) and replacement deionised water filters(at least once a year) (€200), to ensure maximum conductivity of 10-5μsiemens/cm.

The benefits related to production using laser and TIG versus the different costs of the twotechnologies will need to be weighed. A TIG workstation costs about €5,000 and has an hourlycost of €10 compared to €50 for laser. On the other hand, the laser processing is crucial in thecase of delicate or precise welding: it enables much higher precision, much smaller thermalaffected zone, and cheaper finishing costs. Moreover, small or complex weld positions areimpossible to reach using TIG.

Laser welding requires a certain level of process and metallurgic competence; therefore, it isrecommended that operators have some welding experience.



LASER WELDING PROCESS 22

3.4 LASER WELDING PROCESS

Section 2.3 described a laser welding application that is believed to be particularly suitable forSMEs because of its relatively low level of complexity and capital requirements.

Laser welding is a relatively new process, and it is usually capital-intensive industries that use itshigh power applications. In processes based on fusion, lasers supply sufficient heat to melt the

material, and subsequent solidification creates the joint. The melt material could comprise thetwo parts to be joined (joint welding) or a filler wire (deposit welding).

The amount of heat that is brought to the welding area has to be higher than the heat that isdissipated, which depends on the reflection coefficient of the material(s) and the laser

wavelength. The transmission of heat inside the material is based on an effect known as keyhole.In keyhole welding, a high power density >106 W/cm2 produces metal plasma in the material,which enhances heat absorption and penetration. If there is insufficient power, the keyhole is notgenerated, heat is transferred by conduction only, and penetration does not occur.

Lasers generate two types of plasma:

• metal vapour plasma, useful if it is inside thekeyhole, harmful if it is above the materialbecause it absorbs power;

• gas ionization plasma above the material,harmful because it absorbs power.

These plasmas can be eliminated by a flow of blown gas during the process. This gas can beinert or capable of high-ionisation and serves twopurposes: it covers and protects the melt pool andremoves the plasma.

The parameters (see Figure 36: influence factors)that must be considered in relation to laserwelding are:

• laser power, which determines the penetration depth and the welding speed (see Figure 33:temperature and welding section);

• welding speed, which determines the penetration depth (see Figure 35: speed, power andpenetration);

Figure 32: Reflection coefficient,wavelength, materials




• type and flow of protection gas, which influence the quantity of plasma, the power required forthe process, the penetration depth and the welding speed;

• focal point position, which determines the distribution of power in the material, the penetrationdepth, the joint width and the welding speed.

Figure 33: temperature and welding section Figure 34: plasma generation

Figure 35: speed, power and penetration Figure 36: influence factors

The most common types of joints accomplished by laser welding are:

• lap seam (see Figure 37: lap seam welding and Figure 38: lap welding cross section),

• butt welding (see Figure 39: T-joint schemes and Figure 40: T-joint cross section),

• T butt (see Figure 41: butt weld schemes and Figure 42: butt weld cross section).




Figure 37: lap seam welding scheme Figure 38: lap welding cross section

Figure 39: T-joint schemes Figure 40: T-joint cross section

Figure 41: butt weld schemes Figure 42: butt weld cross section

ADVANTAGES AND DISADVANTAGES OF LASER WELDING

The main advantages of laser welding are high penetration and speed, reduced HAZ and highprecision and good final quality. On the other hand there are disadvantages, such as the need forcomplex and precise equipment, complex and expensive laser head motion, problems related touse of filler materials, and the very precise alignment of the joint profile and the beam. In terms of this alignment, a rule of thumb is one-tenth of the thickness with a maximum gap equal to 0.1mmalong the profile. It is extremely important that the two parts are cut and coupled with strict

tolerances and that the materials are carefully chosen. R&D in this area is ongoing; laser welding system sales reflect these disadvantages and are much lower than those for cutting or marking systems. 3D applications are mainly confined to capital intensive industries.

ALTERNATIVE TECHNOLOGIES

Comparison with other welding technologies can help in the choice of the most appropriatetechnology:

• the electron beam has high power density and penetration, but requires quite complexequipment that tends to incorporate little flexibility;

• TIG has good but lower than laser penetration, can be used manually and is less expensive in

terms of equipment. The HAZ is normally wider than with laser;




• Metal Inert Gas (MIG) and Metal Active Gas (MAG) have good penetration, but lower than laser,are less sensitive to the joint gap because they allow the use of filler materials, have a widerHAZ, can be used manually and are less expensive than lasers.

MATERIALS

Laser welding is used for particular materials. With stainless steel it provides good welding, quite

good tolerance on technological parameters, good mechanical joint properties and does notrequire protective gas.

Carbon steels are normally capable of being welded by lasers, provide less tolerance thanstainless steel in terms of technological parameters, provide good mechanical joint properties,and are sensitive to oxides requiring welding to be done in an oxygen free atmosphere. They donot require the use of protective gas. Galvanised steels have similar characteristics to carbonsteels in terms of suitability for laser welding with the addition that the zinc vapours are producedbefore the melting temperature of the steel is reached, which affects the weld pool. This problemis resolved by the introduction of a 0.1mm gap to facilitate vapour exhaust.

Laser welding of aluminium allows is only possible for some alloys; the mechanical properties of joints are lower, welding speeds are high, and protective gas is required.

APPLICATIONS, EQUIPMENT AND PERSONNEL

Laser welding is common in the automotive sector for tailored-blanks and production of mechanical components including gears, and in the food and medical industries for aesthetic andprecise welds.

In the power range 3kW-4kW, five-axis CO2 laser equipment is suitable for welding items up to1,500mm x 3,000mm x 500mm volume. This would require an investment of between €0.6-1million, plus approximately 10% for installation and training. Welding masks and fixing toolsdepend on product design and flexibility required, and their costs can range from a few thousandEuro for simple items that can be produced internally, to hundreds of thousands of Euro forcomplex items. Where electricity supplies are not stable, adequate power infrastructures need to

be in place (UPS, generators). It should be remembered that joints have to be designed for laserwelding, which may require part or all of the existing engineering drawings to be reviewed.

In terms of infrastructure and power supply, these welding lasers require voltage fluctuations of less than ±10%, wall-plug power of up to 100kW, and gas purity similar to that for laser cutting

equipment (see Section 3.1 CUTTING).

Costs differ from country to country and are mainly related to power, gas supply (may be the samecost as for electricity but could be twice as much depending on the application and the materials),loading and off-loading operators, and depreciation.

Capabilities in welding and laser welding in particular, are not as formalised as they are for lasercutting. Thus, practical experience is very important. Operators must be skilled or trained in CNCprogramming, in welding processes and in welding preparation and coupling. In the case of

repeat products of simple design, learning to use the welding equipment may take months;additional training is needed if a new process needs to be engineered.

Progressive training, from spot welding of flat rectilinear profiles to curved profiles, throughpolyhedron edge welding, might be the solution.

Figure 43: pump components Figure 44: stainless steel container



NON-METAL APPLICATIONS: TEXTILES, GLASS, AND OTHER26

4 NON-METAL APPLICATIONS: TEXTILES, GLASS, AND OTHER

OVERVIEW

Lasers are used in the manufacture of clothing and accessories, shoes and decorative items innon-metallic materials. Several new businesses are based on the use of commercial low-powerlaser systems for cutting and engraving fabric, leather, wood, paper and many other materials.

If cutting activities predominate, a plotter cutting machine may be suitable for both cutting (athigh speed) and marking (at slow speed). In the case that high marking productivity is required,then a plotter machine for cutting and a separate marking machine 10-30 times faster may bepreferred, depending on available finance.

The systems for this type of processing normally use CO2 laser sources with power ranging from30W for low volume use to 400W for high volume or industrial use. The systems normally includethe laser source, the mechanics for beam positioning, the software and the safety devices; somealso include the vacuum and filtering unit and a range of other options. Full enclosure of theworking area allows the equipment to be classified as safety class I, reducing the safetyrequirements in the workshop. These machines are easy to use and low maintenance since theonly interface with the operator occurs in up-loading the raw material, uploading the

drawing/pattern file, waiting for the work to be finished, and off-loading the finished product fromthe machine. Monthly maintenance to keep the machine in good operative condition should bescheduled.

In terms of shop-floor requirements, as this is sealed-gas equipment, there is no need for highpurity gas supplies. The main requirement is for a stable single phase 220V/110V energy supply.The sealed gas units can be recharged when the lasing gas is exhausted. The equipment isdesigned to work in a temperature range of 10°C-40°C and 10%-85% humidity. For higher powerthan 60W, the OEM may recommend water cooling and in the case of tropical environments, achiller.

In the case of low temperature environments, the laser source should not be allowed to freeze asthis could permanently affect its operation. For the first shift of the day in the winter time, a warm-

up procedure may be needed, as indicated by the OEM.

Power consumption depends on the laser output power, and the speed and thickness of thematerial, and will range between 1kW and 7kW. An area of approximately 1,500mm x 1,500mm x1,200mm will be required to house the machine, depending on the model. It should be capable of bearing loads exceeding 300kg.

Cut accuracy is about ±0,1mm, repeatability <±15μm. In terms of writing speeds, the mostadvanced equipment can exceed 3m/s with accelerations of 8g with linear motors.

THE PRODUCT

Various materials can be processed by these lasers including:□ wood for wooden toys, customised furniture, veneers (see Figure 46: wood veneer), parquetry

for mosaics;

□ leather for shoes, bags and other fashion items (see Figure 45: clothing accessories). Cutting speeds can range from 50 to 100mm/s on leather of 2mm thickness;

□ textiles, for decorative clothing (Figure 47: decoration on denim, this took 4 seconds with a30W marking machine; to decorate one side of a pair of jeans could take up to 1 minute with a100W machine), micro perforation for technical textiles;

□ embroidery: in a production line, laser machines can cut the appliqué needlework afterembroidering (see Figure 48: embroidery cutting);

□ paper for stencils, piercing, papers for the printing industry;

□ acrylic tissues;



NON-METAL APPLICATIONS: TEXTILES, GLASS, AND OTHER 27

□ plastic and rubber for industrial product identification, decoration, gaskets, tampo-graphicclichés and rubber stamps;

□ welding of transparent plastic parts, such as Plexiglas on opaque plastics;

□ plastic components for electronics, such as polyester and polycarbonate membranekeyboards, phones.

The dimensions of the raw sheets can be up to 1,200mm x 700mm, and can range in thicknessfrom very thin to 200mm or more and up to about 25kg in weight.

Although the equipment is flexible in terms of raw materials types and surface finishing, for someaspects it may be necessary to consult OEMs. For example, plastic items, such as PVC3 and PET,need special care because of health-hazardous vapours, e.g. dioxins, that are released in thelaser process. It may be necessary to install special filters. Denim and some other textiles andflexible materials may need a vacuum table in order to keep them flat to enable accurate cutting and prevent fires.

Laser marking can make the chemicals, such as disposable acids, used in traditional processing methods, redundant. It also guarantees better replication than mechanical wear-effect tools(which often were manual).

Figure 45: clothing accessories Figure 46: wood veneer

PERSONNEL AND EQUIPMENT

In terms of skills, operators must be able to use computers in order to load drawings and CADsystems in the case that a new design is required. Up/off-loading machine operators do notrequire any particular capabilities. In some cases, the equipment is configured the same as in aPC compatible printer.

At the time of writing, a standard cutting plotter represented an investment of €10,000 for low-volume low-power (25W output) applications or €70,000 for high speed cutting (for thick wood)(350W output). Marking equipment costs from €20,000 for 30W equipment to €100,000 for350W plus equipment for specific applications; most of this cost is in the laser source.

Installation and training probably involves two days and up to €1,000 depending on the distanceof the OEM from the customer’s premises.

Depending on the application, other investments might be considered worthwhile, e.g.:

□ vacuum table for textiles, which would cost around €5,000;

□ vacuum and filtering units, at a cost of €10,000 for the above mentioned power ranges(required where PVC, PET, ABS, chrome tanned leather or other heavy contaminants areinvolved);

□ equipment enclosures with suitable materials to upgrade safety from class IV to class I, whichcould cost between €3,000 and €10,000, depending on the dimensions;

□ water chilling units.

3Some legislations do not allow processing of PVC because of the dioxins generated,



NON-METAL APPLICATIONS: TEXTILES, GLASS, AND OTHER28

Running costs are mainly related to power, ranging from 1kW-7kW, and the hours of use, the dutycycle, the model, and the maintenance cycle. The latter includes:

□ effective suction (and in certain cases, compressed air) is required to maintain the reliability of the machine. If contaminants are not removed this could reduce the life of the mechanicalguides from two years to six months, involving approximately €1,500 investment persubstitution;

□ cleaning of filters at least once a year, and more often in the case of dusty applications andcontaminating materials;

□ daily or weekly cleaning of lenses and mirrors. Dirty optics and dust deposits can causefailures due to the laser not being completely reflected, causing overheating and damage tothe material. New lenses cost €150-300;

□ gas refills for the CO2 laser. Depending on the manufacturer and the model, in most low powerlaser sources, the gain medium is sealed and does not require to be refilled. For medium tohigh power, it should be refilled every 5,000-10,000 hours at a cost of around €2,000 (orevery 20,000 hours at a cost of €15,000 for 30W equipment and €30,000 for 115Wequipment). Some OEMs exchange exhausted tanks for full ones; others require the tankchange to be carried out by one of their employees.

Figure 47: decoration on denim Figure 48: embroidery cutting



FASHION MARKING 29

4.1 FASHION MARKING

Lasers facilitate the adoption of new designs, interpretation of stylists’ ideas, unpredictablequantities and short time-schedules common to the fashion sector. This is the case in a small (3employees) company, which uses eight CO2-laser machines to process a range of textilesincluding cotton, polyester and technical tissues for their customers. Graphic skills, speed,definition and know-how about materials and machine configuration, accrued through some 4-6

years of experience in the company enable the company to deliver prototypes and then producein bulk according to a time schedule.

The fashion sector has pronounced seasonality. In February, for instance, a stylist might bring aconcept sample to be interpreted, designed and prototyped by March. Two months later, thecompany could receive orders in quantities ranging from a few thousand to hundreds of thousands of items, required for delivery to retail shops in July. Unexpected repeat orders arequite common. To accommodate these, the company calls on the services of a pool of 20temporary workers, with experience in using lasers.

A graphic designer, a skilled machine operators and a stylist together decide on the best graphicfile for laser production. Their know-how allows them to render the idea graphically, and definethe appropriate configuration of laser power and speed to achieve the desired edge finishing, or

the precisely-graduated wear-effect, with tight tolerances and high replication for bulk production.

Figure 49: graduated wear-effect on

denim

Figure 50: composed pictures

Figure 51: marked golf with laser

machining detail

Figure 52: holes in technical tissue

The following parameters are important for quality marking and cutting:□ flatness of the tissues on the working table, required for proper definition, and can be

supported by a vacuum table although seams and pockets, etc. make complete evennessdifficult to achieve;

□ operating area width: the wider the area, the less defined the work with the same machine;□ material: a percentage of synthetic fibre improves cauterisation (thermo-welding) and reduces

fraying;□ colour: thermal affected zones show up less on darker dyes. Colour changes resulting from

laser treatment are more common in immersion-dyed and wire-dyed textiles.



FASHION MARKING30

Figure 53: marked hearts on thick tissue Figure 54: cut and marked accessories

The power of equipment used for CO2 marking, ranges from 60W to 400W, enabling worksurfaces of 250mm x 250mm up to coils of tissue bigger than 2,200mm. The marking equipmentcan also be used for cutting. The investment is largely proportional to laser source power andranges from €100,000 to €250,000 per machine. The case company made its equipmentpurchases based on the expected market and products rather on power criteria.

Figure 55: Textile marking lay-out

A typical SME investment decision process for laser equipment for the fashion industry wouldinclude:

• benchmarking equipment in terms of types of laser decorations. This could include typical weareffects, stripe-construction, image impression, and paper-model cutting. The equipment wouldlikely require one operator and an area of 30m2-40m2;

• budgeting in relation to appropriate graphic workstations and software (normally commercialsoftware is available). The area required for a graphic workstation and an operator would beapproximately 25 m2;

• budgeting for the data sharing system, which could include a LAN (100Mb/s should be suitablefor a SME but bigger operations might require 1000Mb/s) to connect the workstation, the laserand a server to archive the data typical of any material or process. Formalisation/codificationof the know-how (materials, procedures, processing parameters) is more helpful than tacitknowhow which requires face to face transmission of knowledge;

• budgeting in time needed for training of operators and trials.

The main running costs for lasers are related to electricity usage, replacement of lasing gas, andmaintenance of optics and electronic components, which is carried out, machine by machine,

while temporarily inoperative.

This benchmarking may require companies to compare the outputs of three analyses:

Preparation

area

2

3

4

6

7

8

51

Temporary

storage

1, 2, 3, 4, 5, 6, 7, 8:

CO2 markingstations

: individual

buffers

Quality control is

carried out at each

marking station by

the operator



FASHION MARKING 31

• monthly costs, such as the space rent, machine leasing (or loan and depreciation), staff costs,previous running costs, other costs (such as overheads), expressed as cost per second.Absolute costs will vary from country to country; however, estimates might be 45%-50% for theleasing instalments, 35%-40% for operators, 8%-15% for space rent, 5%-7% for maintenanceand consumables;

• time and cost to finalise the graphics for typical decorations/works and to produce a lasered

prototype. Based on the estimated cost per second and the time schedule for production, thecost per prototype, and the number of pieces per day and per month. Timing will be highlydependent on factors such as complexity and operator skills; however, a ball park figure mightbe 1 hour for a wear effect, 2 hours for a stripe-decoration, 3 hours for an image impression,and half an hour for paper-model cutting;

• average time and cost to produce typical products in batches or in series. Based oncost/second and time/piece, the cost of the product and the number of items per day or monthcan be calculated, based perhaps on more than one minute for the same wear effect as above,about 2.5 minutes for the stripe-decoration, about 6 minutes for the image impression, andbetween 3 and 12 minutes for paper-model cutting, depending on the technology.



TEXTILE PATCH PRODUCTION 32

4.2 TEXTILE PATCH PRODUCTION

Inkjet printing and laser cutting allow SMEs to produce textile patches.

Industrial embroidery is becoming more capital intensive in order to process sufficient volumecompetitively. Specialised machines with multiple embroidery heads that operate 24 hours/dayand 7 days/week, combined with laser cutting heads, are capable of large volumes of outsourced

production in globalised value chains. This greatly reduces the margins for SMEs that produceembroidery on a smaller scale.

The SME has two alternatives: higher value added embroidery or inkjet plotted patches to beprocessed on the fabric or to be cut and applied afterwards. Sealed CO2 lasers can be used tosupport cutting and application for both embroidery and printed patches.

Value added embroidery requires capabilities in terms of knowledge about the mechanicalproperties of the fabrics being coupled (e.g. a very tough patch could stretch the base material),resulting in the mechanical setting of the machine requiring frequent intervention. Investing inmachines with laser heads coupled with embroidering heads will bring advantage because off linecutting solutions do not guarantee quality.

Figure 1: Embroidery with laser cutting

In the case of embroidery with laser cutting, flexibility in changing the design (and machine set-up) from one batch to another and the capability to produce complex designs are of fundamentalimportance and require fairly high level skills and good machine operation. An eight-headembroidering machine and related services will require one operator and 50m2 of space. Outputin terms of embroidering should be 200 pieces/day.

Figure 2: embroided item Figure 3: embroided and laser cut item

Inkjet patch printing and laser cutting are also low cost opportunities for SMEs. The investmentrequired is significantly lower than for embroidering machinery, i.e. in the range €30,000-€50,000 rather than €100,000-€150,000. The machines require the same amount of space i.e.50m2, but the overall dimensions of the plant will be less than 300m2. The inkjet and lasersystems can work on rolls of 1.5m width and produce up to 5,000 patches per day, which canthen be applied by small hot-presses at a rate of 400–500 pieces per day per operator. A smallpress costs approximately €2,000. SMEs may consider outsourcing batches of over 10,000 itemsto specialised suppliers, for delivery within say 30 days. At the time or writing, this was a lowercost option and allowed more flexible and more remunerative smaller batch operations in house.



TEXTILE PATCH PRODUCTION 33

Figure 4: printed, cut and applied

patchesFigure 5: multicolour printed patch

Printing is also a simpler operation than embroidering for an SME as it is configured as a plotterto the PC and can be executed on the finished garment, providing the flexibility to cope withsudden variations in fashion or promotional demands (e.g. the launch of a new product, theopening of a new branch, special events). Given the innovation in fabrics, and in printing filmsand inks there is a big margin for experimentation. It is possible to program laser heads to

contour patches and mark some design on the inside of the item. Before the introduction of thelaser and the inkjet systems, the industry used serigraphy and shears that cut up to 20 layersoverlapped, which provided much less flexibility.

One skilled operator is required for the printing and cutting machine, one for graphic design andone for the hot-presses. A new printing and cutting operator, without formalised training, will taketwo years to become skilled in the job, involving much learning by doing and the associated costs;to learn the skills of embroiderer takes three years. In order to reduce these costs, SMEs may payfor operator training, perhaps in a more experienced company.

Inkjet printing and a laser cutting system would add the following costs: 40%-45% for inks andprint-base films, 20% for press personnel, and 20% for graphics personnel, 7%-8% formaintenance (in the case of embroidering this would be around 35%).



CRYSTAL PROMOTIONAL GADGETS 34

4.3 CRYSTAL PROMOTIONAL GADGETS

The promotional gadget industry customises items such as pens, folders, key holders, crystals,etc. with company names or logos, or personal images commemorating special occasions, e.g.,anniversaries, inaugurations, new product launches and others, that occur throughout the year.

Competition in standardised items and cheaper raw-materials (lead content less than 19%) has

led to a margin-competition market, in which economy and premium products are differentiated.In our case firm, a 1999-registered-SME engraves 2D and 3D images inside crystals, showing software-graphic files or images of a person, if a scanner – or multiple scanners - captures theinput. Crystals can measure up to 200mm x 100mm x 100mm.

Most of the time, graphic and laser machine operators work together on a 1 shift/day basis; attimes of peak demand personnel numbers increase and work occurs in a two or three shiftoperation.

Figure 6: 3D Engraved

crystals

The company relies on four diode-pumped green and infrared Nd:YAG machines with 7-8W peak-power that can accommodate 1,000 points/second up to 3,000 points/second. Depending onthe item design and the machine model, the engraving cycle can last from 1-20 minutes. A laser

machine can engrave one item per session or multiple items using a moving 400mm x 600mworktable and automatic loading and off-loading devices. The investment required for suchequipment at the time of writing, ranges from €50,000 to €250,000.

Key parameters are the power, the speed, the temperature and humidity of the environment, andthe raw materials. Raw material composition, which can vary from lot to lot, influences theconfiguration of the machine and the duty cycles; in the absence of certification of thecomposition, in order to avoid cracks in the crystals, a series of trials will be necessary beforestarting production.



LASER INSPECTION 35

5 LASER INSPECTION

OVERVIEWLaser inspection is a visual verification and checking on 2D and 3D parts through a laser scanthat collects hundreds or even thousands of points per second with a certain degree of accuracy(in commercial devices ± 0.05mm) and can digitise an image that can be compared with a CADdrawing. The technology is also suitable for reverse engineering.

3D laser scanning is suitable for dimensional inspections, for instance, in automotive chassis, incast parts, such as engines or for weld checks/tracking in pipes. Commercial technologies canscan a complicated automotive 50mm x 20mm shaped metal-sheet item with holes, in 4 minutescollecting 1.6 million points in this timeframe.

This chapter discusses flat part inspection directly on the shop-floor, on-line or off-line, in whichthe laser scan compares the item with the form and the tolerances required by the CAD.

The technology enables significantly shorter inspection times (and therefore lower costs of machine downtime) than other optical or coordinate measuring systems, the possibility to getautomated statistical process control reporting and the possibility to reverse engineer parts.Normally checks are carried out on first article inspection in the first batch to reveal any design,

tooling or other problems, enabling reconfiguration before main production thereby reducing scrap costs.

This type of equipment requires stable 220/110V electric power and a LAN to load CAD drawings,involving investment of the order of €70,000. Training personnel on software and machine usetakes approximately 3 days.

In terms of running costs maintenance consisting of cleaning and periodic substitution of theglass surface is the most expensive, and could be up to several hundred Euros per month,cleaning projector filters and in some cases re-calibration are required once a month. Commercialsystems do not require programming and self-calibrate at each check. Experience shows thatpayback is around 1-2 years.

2D commercial devices scan with a visible laser diode beam at power in the range of mW, taking approximately 500 points per second, and an inspection cycle of seconds or minutes.

The parts typically requiring inspection are the opaque components (in metal, plastics, paperproducts, composite materials, rubber, cork, vinyl, felt, leather and fabrics), which are less than2,440mm x 1,220mm with thicknesses up to 200mm and weighing up to 130kg.

Where the piece is wider than the standard worktable, it is possible to merge multiple inspectionscarried out by a single scanner or multiple scanners.

Figure 7: 2D laser inspection equipment



LASER INSPECTION 36

6 LOOKING AHEAD

Lasers are a standardised technology in many manufacturing contexts; their use could increasedepending on how well they answer certain economic needs. These can be summarised asreducing energy consumption (higher efficiency), lower maintenance costs (e.g. by improved optic

alignment), lower level financing (lower initial capital cost) and lower facilities costs (cooling, floorspace). The more mature CO2 and lamp-pumped Nd:YAG technologies will continue to undergoimprovement to meet these demands. However, it is expected that other technologies such asfibre lasers, diode lasers, diode pumped Nd:YAG and disc lasers will be more efficient and willprogressively erode the market share of these two technologies in areas such as welding andcutting, and will enlarge the spectrum of applications to 3D remote welding, micro-welding andprocessing and portable processing.



BIBLIOGRAPHY 37

7 BIBLIOGRAPHY

Below is a list of some useful reference works on lasers for materials processing:

1. Laser Institute of America LIA Handbook of Laser Materials Processing , Orlando: MagnoliaPublishing, (2001).

2. John Powell, Laser Cutting , London: Springer Verlag, (1998).

3. Walter Koechner, ‘‘Solid-State Laser Engineering’’, Springer (1996).

4. Dieter Schuoker, ‘‘High Power Laser in Production Engineering’’, (1999).

5. Walter W. Duley, ‘Laser Welding’, John Wiley & Sons inc. (1999).

6. Orazio Svelto, Principles of Lasers, (V ed.), Plenum Press (1999).

The following articles appear in major scientific and specialist commercial magazines or onuniversity websites. Many are subject to copyright and can be purchased over the internet orobtained through the local university library system or through the German National Library of

Science and Technology (Technische Informationsbibliothek Universitätbibliothek Hannover,http://www.tib.uni-hannover.de/en/) at nominal cost.A summary of each article is provided at the end of this list, which may be useful if access tointernet or university database is not easy.

Table 1: year-sorted reference articles

ID TITLE YEAR AUTHOR SOURCESummarypage

1 Laser marketplace2007: diode lasermarket takes abreather

2007 Robert V. Steele LaserFocusWorldmagazine

41

2 Laser marketplace2007: laser industrynavigates back toprofitability

2007 Cathy Kincade;Stephen Anderson

LaserFocusWorldmagazine

41

3 Laser versus labour 2007 Tim Heston Fabricating andMetalworking magazine

43

4 Non traditionalmachining applications

2007 DIMEG Dipartimento diInnovazione Meccanica eGestionale DIMEG,Università degli Studi diPadova

43

5 Elliptical beam speeds

laser cutting

2007 LaserFocusWorld

magazine

43

6 Laser water jet coolsand cuts in the materialworld

2007 Jacqueline Hewett Optics and laser Europemagazine

43

7 New laser exportcontrols set to takeeffect

2007 Breck Hitz Leoma Photonics Spectra 43

8 Laser marketplace2006: diode doldrums

2006 Robert V. Steele LaserFocusWorldmagazine

44

9 Laser marketplace2006: market’smessages are mixed

2006 Cathy Kincade;Stephen Anderson


44



BIBLIOGRAPHY 38


10 Integrated sheet-metalproduction planning forlaser cutting andbending

2006 B. Verlinden, D.Cattrysse, D. VanOudheusden

International Journal of Production Research

44

11 Fibre lasers make their

mark

2006 Kimberley Gilles Welding design and

fabrication magazine

45

12 Metal cutting at lightspeed

2006 Richard Mandel Welding design andfabrication magazine

45

13 Super saver laser 2006 Daniel Margolis Cutting tool engineering magazine

45

14 3D advancedtechnologies inspectionmake food inspectionpalatable

2006 Winn Hardin Machine Vision On-line 45

15 Development of atechnology of two-beamlaser welding and full-size tests of oil and gastransmission pipes

2006 AG Grigor Yants,AN and NV Grezev,IA Romanov,VI Kazachkov,FD Nuriakhmetov,VN Goritskii

Welding international 46

16 Fibre lasers: emerging in major markets

2005 Bill Shiner IPG photonicsCorporation The 2005photonics handbook

46

17 Cost forecasting modelfor order-based sheetmetalworking

2005 A. Bargelis; M.Rimasauskas

Proceedings of Institution of MechanicalEngineers

46

18 A plan for productivity.Laser cutting and

welding shops fighttough competition

2005 Charles Bates Welding design andfabrication magazine

47

19 Laser like focus. 2-Dand 3-D laser cutting machines add value toshops

2005 Susan woods Cutting Tool Engineering magazine

47

20 Very focused 2005 Andy Sandford Metalworking productionmagazine

47

21 Impact of industrialneeds on advances inlaser technology

2005 Paul Denney Critical Review: industriallasers and applications.Proceeding of the SPIEvol. 5706

47

22 Trends in laser materialprocessing for cutting,welding, and metaldeposition using carbondioxide, direct diode,and fibre lasers

2005 Wayne Penn andthe Alabama LaserTeam

Critical Review: industriallasers and applications.Proceeding of the SPIEvol. 5706

48

23 Fabrication of 3-Dcomponents by laseraided direct metaldeposition

2005 JyotirmoyMazumder,Huan Qi

Critical Review: industriallasers and applications.Proceeding of the SPIEvol. 5706

48

24 Development andtrends in laser welding

of sheet metal

2005 F. Vollertsen Sheet Metal 2005,Proceedings of the 11th

conference

48



BIBLIOGRAPHY 39


25 High-power fibre lasers– Application potentialsfor welding of steel andaluminium sheetmaterial

2005 C. Thomy,T. Seefeld,F. Vollertsen

Sheet Metal 2005,Proceedings of the 11th conference

49

26 Small devicesmanufacturing bycopper vapour lasers

2005 S. G. Gorney, I. V.Polyakov, M. O.Nikonchuk

Micromachining andmicrofabrication processtechnology, Proceedingsof SPIE Vol. 5715

49

27 Fabrication flexibility. AtWork in Brazil’s ‘no-till’zone

2004 Tooling and Productionmagazine

49

28 Let there be light 2004 John Excell Design engineering magazine

49

29 Machine vision guideslumber cutting

2004 Yvon Bouchard,Philip Colet


49

30 Material processing with fibre lasers

2003 Ruediger Hack Industrial LaserSolutions magazine

50

31 CO2 lasers make thecut

2003 Holger Schülter Photonics Spectra 50

32 Fibre lasers grow inpower

2002 ValentinGapontsev,William Krumpke


50

33 Towards real-timequality analysismeasurement of metallaser cutting

2002 Cesare Alippi,Vincenzo Bono,Vincenzo Piuri,Fabio Scotti

VIMs 2002 InternationalSymposium on Virtualand IntelligentMeasurement Systemproceedings

51

34 ICS lectures onindustrial application of lasers

2000 N. U. Wetter, W.De Rossi, F.Grassi, W.M.Steen, SperoPenha Morato

ICS UNIDO publication 51

35 Laser applications inelectronics andoptoelectronics industryin Japan

1999 Kunihiko Washio SPIE conference on laserapplications inmicroelectronic andoptoelectronic

51

36 Laser cutting: industrialrelevance, processoptimisation and laser

safety

1998 H. Haferkamp, M.Goede, A. VonBusse, O. Thürk

Part of the opto-contactworkshop on technologytransfers, start-up

opportunities andstrategic alliances,Québec, Canada

51

37 High power fibre laser 1991 V.P. Gapontsev;L.E. Samartsev

Institute of RadioEngineering andElectronics; USSRAcademy of Science

52

.



40

8 SOURCES OF INFORMATION

USERS OF LASER SYSTEMS

COMPANY APPLICATION LOCATION

1 A4ricami Srlwww.a4ricami.it

Embroidery and textile patch production Correzzola (PD), Italy

2 Cantuna Cut Srlwww.axprofessional.it

Metal sheet laser cutting and marking and tooling production

Pieve D’Alpago (BL),Italy

3 Demont Srlwww.demontpromo.com

Promotional items Bassano del Grappa(PD), Italy

4 Inox Veneta SpAwww.inoxveneta.it

Laser cut food and beverage productionplant components

San Giacomo in Veglia(TV), Italy

5 Laser Style Italia Srlwww.laserstyleitalia.it

Marking and cutting on textiles Fanzolo di Vedelago(TV), Italy

6 Lorenzin Srl Metal sheet laser cutting, bending, andwelding

Sandrigo (VI), Italy

7 M.C.M. Srl Metal sheet laser cutting and fabrication Casalserugo (PD), Italy

8 MED Srl

www.ideamed.net

Health Technologies engineering and

manufacturing

Maserà (PD), Italy

9 Omesa Srlwww.omesa.com

Metal sheet laser-cutting, bending andwelding

Brendola (VI), Italy

10 SAMI-Instruments Srlwww.sami-instruments.com

Petrochemical industry instruments OEM Reschigliano (PD),Italy

11 TEC-SIM Srlwww.tec-sim.com

Pharmaceutical and chemical plantcomponents

Silea (TV), Italy

12 Zero Seven Studiowww.zeroseven.it

Laser Consultancy and Integration

MANUFACTURERS OF LASER SYSTEMSCOMPANY APPLICATION LOCATION

1 Prima Industrie SpAhttp://www.primaindustrie.com/

Laser cutting, welding and marking Collegno (TO),Italy

2 Rofinwww.rofin.com

Lasers for industry Hamburg,Germany

3 Sei SpAwww.seilaser.com

Laser cutting and marking Curno (BG), Italy

4 Sisma SpAwww.sisma.com

Laser systems and laser sources for jewellery

Schio (VI), Italy

5 Trotecwww.trotec.net

Laser cutting, marking and engraving Marchtrenk,Austria

UNIVERSITY

DEPARTMENT SERVICE LOCATION

1 University of Padova,Department of InformationEngineering www.dei.unipd.it

Research, Graduate and Post-GraduateEducation, R&D Services

Padova, Italy

2 Polytechnic of Milan, SITECwww.sitec.lecco.polimi.it/

Research, Graduate and Post-GraduateEducation, R&D Services

Lecco, Italy



41

9 ANNEX: SUMMARIES OF ARTICLE

The following paragraphs provide summaries of the articles in Table 1: year-sortedreference articles at page 37. The summaries do not conflict with copyright orconstitute plagiarism.

1. Laser marketplace 2007: diode laser market takes a breather

By Robert Steele, published in Laser Focus World in February 2007,downloaded at :

http://www.laserfocusworld.com/display_article/283868/12/ARTCL/none/none/LASER-MARKETPLACE-2007:-Diode-laser-market-takes-a-breather

The 2006 diode-laser market had mixed results The diode laser for opticalstorage applications had a downturn due to a maturing market anddecreasing prices. On the other hand, most of the other applications,including high-power-diode applications, experienced moderate growth. Interms of revenue, following three years of steady growth, the market declinedfrom US$3.23 billions in 2005 to US$3.10 billions in 2006. In terms of

volume, there has been a 5% increase, with 815 million diode lasers shippedin 2006 especially in consumer optical-storage applications confirming growing demand, but at lower prices. In 2006 a new generation of highcapacity optical storage technologies, HD-DVD and Blu-ray, was introduced. Intelecommunication lasers, growth occurred in every segment: long-haul,metro and access. Tuneable lasers saw rapid growth. Average power andsales of pumping lasers increased while unit prices decreased and anothertwo years of good results was expected. Fibre laser pumping diodes showedhuge increase with 90% of the market going to IPG Photonics. The articledescribes the market situation for other applications (LAN, bar code scanning,sensing, entertainment, inspection and measurement) and diode-laserproducts and configurations and describes the methodology used to collect

the data.

2. Laser marketplace 2007: laser industry navigates back to profitability

By Kathy Kincade and Stephen Anderson, published in Laser Focus World in2007, downloaded at: http://www.laserfocusworld.com/articles/282527

The 2006 worldwide laser business was surprisingly strong thanks, in largepart, to better-than-expected performance by the semiconductor industry andthe rebound of optical telecommunications. Non-diode laser sales grew 11%while a general positive unit growth for diode lasers was offset by generallydeclining prices with -4% in sales. A total market of US$6 billion with an 8%revenue increase for all lasers was forecast for 2007. A fluctuating monetary

situation and renewed interest venture capital in optics and photonics-relatedventures will affect the future market. The European market grew by 12%-15% particularly in Germany, Benelux, the UK and Italy, but also in severalEastern European countries. The Asian market continues to represent greatpotential for laser and photonics, with China considered to be more aproducer than a consumer. Important issues are the progressivedisplacement of non-diode-lasers by diode-lasers from medical therapy to thegraphic arts, the growth of solid-state lasers, the challenge from fibre-lasers,which grew 55% in terms of revenues between 2005 and 2006 and continueto erode the market for lamp- and diode-pumped solid state lasers. Growth insemiconductor manufacturing shows promise for the optoelectronics industrywhile material-processing high-power (around 6kW) CO2 lasers as well as

laser marking systems grew by about 10% reaching US$1.7 billion in 2006.The article reports the situation in the market for lasers for scientificresearch, instrumentation, image recording, entertainment and display and



42

military and aerospace applications. There is a description of how the datawere collected.



43

3. Laser versus labour

By Tim Heston, published in Fabricating and Metalworking in 2007,downloaded at : http://www.fandmmag.com/print/Fabricating-and-Metalworking/Laser-versus-Labor-/1$219

The article discusses optimising job-routines, planning and bottlenecks

through investment in automation and equipment as part of leanmanufacturing. Investing in high-end equipment can reduce bottlenecks andoptimise flows. Skilled machine operators represent value added, reflected inthe normally increasing wages versus equipment depreciation andincreasingly tougher market competition. It is necessary for job-shops toanalyse operator tasks when machines are operating to avoid skilled operatortime being spent on low-end activities. For instance, material handling andtool change-out can be achieved by automatic specialised nozzle-lenschanges. Instead of focusing on cutting speeds, job shops should look at howmany parts can be completed within a certain time, which will be increasedwith the application of automated materials handling, automated tool changeand especially by a good manufacturing plan from estimation to delivery,

through scheduling, production, post process inspection. Many job-shopshave moved to 3D laser cutting, a smaller but higher margin market that cancomplement 2D works.

4. Non traditional machining applications

By the Department of Innovation in Mechanics and Management of theUniversity of Padova, Italy, downloaded at:http://www.dimeg.unipd.it/didattica/tecme4/8_Non_conventional.pdf

The text is part of a university course in Mechanical Technologies anddiscusses elements of so-called non-conventional-machining technologies.The presentation encompasses: applications, and many types of machining

including laser, chemical, thermo-chemical, ultrasonic, water-jet, abrasive-jet,electric discharge, electron beam and electro-chemical machining andgrinding. The text provides a schematic illustration of the laser machining process, the applications, the characteristics, and advantages anddisadvantages.

5. Elliptical beam speeds laser cutting

Published in Laser Focus World in January 2007 downloaded at:http://www.laserfocusworld.com/display_article/282651/12/ARCHI/none/NBrea/Elliptical-beam-speeds-laser-cutting

The article focuses on a specific commercial application to accelerate siliconwafer cutting. The elliptical beam enhances cutting speeds by 3 to 4 timesfrom 16.7mm/s to 62mm/s.

6. Laser water jet cools and cuts in the material world

By Jacqueline Hewett and published in Optics and Laser Europe magazine inMarch 2007, downloaded at: http://optics.org/cws/article/industry/27415

The article focuses on a commercial application that directs a laser beam intoa thin water-jet technology to cut, drill and dice materials as varied as galliumarsenide and polycrystalline diamond. The advantages are no heat-affectedzones, parallel kerfs and the ability to cut thick and hard materials. The water

jet cools the work piece between laser pulses and expels molten materialsfrom the cut.

7. New laser export controls set to take effect



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By Breck Hitz of LEOMA and published in Photonics Spectra magazine inJanuary 2007, downloaded at:http://www.photonics.com/content/spectra/2007/January/features/86091.aspx

The article describes recent changes to the Wasenar export controls

compared to the early 1990s. These export controls are aimed at potentiallycritical military laser applications. The article lists the countries that havesigned up to the Wasenar agreement and the criteria for free-export vslicensed-lasers such as power, wavelength, and overall efficiency.

8. Laser marketplace 2006: diode doldrums

By Robert V. Steele and published in Laser Focus World magazine in February2006, downloaded at: http://www.laserfocusworld.com/articles/248128

The article describes the diode laser market situation in 2006. Althoughseveral segments, particularly telecom and high-power applications, havegained, price erosion has restrained revenue growth for the optical-storagesegment after a flat 2005. The diode market in 2005 was US$3.23 and

represented 59% of total commercial laser revenues, the most importantapplications being for optical storage (54%). For 2006, moderate growth (9%)was expected for all applications including telecommunications. The articlegives detail on optical storage, telecommunications, high-power diodeapplications, and others. It describes the laser products and configurationsand how the data were collected.

9. Laser marketplace 2006: market’s messages are mixed

By Kathy Kincade and Stephen Anderson, published by Laser Focus World inJanuary 2006, downloaded at:http://www.laserfocusworld.com/articles/245112

The article describes the laser market situation in 2005 with low overallgrowth masking some strong performance. The laser industry is considered tobe maturing, but still at an early stage. Growth is due more to newapplications than to increased volumes. Some system manufacturersregistered major increases over 2004 (more than 14% revenues). Thesemiconductor market has stalled, although sales of flash memories areencouraging. China continues to experience two-digit growth in most sectorsincluding both production and consumption of low-cost laser and lasersystems for domestic industrial applications such as marking and fabriccutting. Europe has not fared as well as expected with only a 3% growth in themachinery sector in 2005. Industrial materials processing (primarily metal-working and marking) have done better. Fibre lasers in general grew 53% on

2004 levels, and +47% from 2005 to 2006 (forecast). Fibre lasers forindustrial applications grew by 33%, of which more than 75% was at theexpense of mainly lamp-pumped Nd:YAG; the CO2 market (mainly for sheet-metal and plate cutting) which was not feeling the impact from fibre. Thearticle describes the medical therapy, basic research, instrumentation, imagerecording, entertainment, military/aerospace laser segments and outlines themethodology used to collect the data.

10. Integrated sheet-metal production planning for laser cutting and bending

By B. Verlinden, D. Cattrysse and D. Van Oudheusden and published by theInternational Journal of Production Research in January 2007, downloaded athttp://www.tib.uni-hannover.de/en/.

The paper discusses the need to reduce scrape material in 2D cutting and thetime-consuming set-ups for 3D bending through the use of an integratedproduction planning model. The single optimised nesting of parts may require



45

additional setups at the press-brake while the proposed model integrates thecreation of feasible grouping of parts and the minimisation of the number of set-ups at the press-brake. The total execution time reduction is expected toexceed 4%, representing an average annual saving of about 10 days.

11. Fibre lasers make their mark

By Kimberley Gilles, published in Welding Design and Fabrication inSeptember 2006, downloaded athttp://www.weldingmag.com/323/GlobalSearch/Article/False/31981/.

The article describes the characteristics and advantages of commercial fibrelasers for marking: high contrast, permanent product identification, and littleprocessing debris. The text reports the improvements brought by the fibrelaser to power and beam quality, and the advantages of laser marking. Itdiscusses the lower levels of debris generated in the marking process whenusing fibre lasers compared to Nd:YAG systems. Other advantages of fibrelasers are small spot size, high beam quality, and compact size. Commercialfibre lasers can avoid distortions - even cutting, welding and marking within

0.1mm. The duration of water cooled fibres is within the 400,000 hours span.However, these lasers are more sensitive to ambient temperature than lamp-pumped lasers.

12. Metal cutting at light speed

By Kimberley Gilles, published in Welding Design and Fabrication magazine inSeptember 2006, downloaded athttp://www.weldingmag.com/323/GlobalSearch/Article/False/31981/.

The article gives an overview of the spread of commercial laser technologiesfor cutting in mid and high volume production shops based on the standardsachieved in the technology. In spite of a high initial capital investment, thelaser achieves higher speeds and reduces overall production costs, bringing aseries of advantages: no tooling, no lubrication, no contaminants, highprecision, replication and the possibility to cut abrasive, sticky and very hardmaterials. Most laser cutting technologies use CO2 and Nd:YAG as the lasing medium. This article reports on the types of cutting systems: flying optics,hybrid and pivot beam. The current equipment operates at 1,000 2mmdiameter holes spaced 3.175mm in a piece of 1.016mm mild steel in 1minute. Lasers can be fitted to industrial robots for 3D cutting with bestresults in drawing stampings, and cutting hydro formed tube sections in therange of 0.5mm to 5 mm. There is a trend for fibre lasers to progressivelyreplace CO2 and Nd:YAG in industrial applications.

13. Super saver laser

By Daniel Margolis, published in Cutting Tool Engineering magazine inFebruary 2006, downloaded athttp://www.ctemag.com/archived.articles.search.php.

The article is about commercial marking solutions. Laser marking systemsrange between US$35,000 and US$150,000, and prices are reducing, vsUS$10,000 for an inkjet printer. However their advantages include:permanent marking, higher graphical adaptability, easier control, noconsumables, no surface degradation, 15 minutes training, and user friendlysoftware. Laser marking systems can be installed in computer numericcontrol (CNC) systems to carry out more operations in parallel. The articlereports on a series of marking manufacturers and forecasts a transition from

the ink-jet to the laser system.

14. 3D advanced technologies inspection make food inspection palatable



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By Winn Harding and published by the Machine Vision Online magazine inAugust 2006, downloaded athttp://www.machinevisiononline.org/public/articles/archivedetails.cfm?id=2827.

The article is on commercial solutions to automatically inspect and analyse

organic products from lumber to chicken, which vary from unit to unit.Traditionally 2D vision systems have been used, but new applications areemerging that require more data at higher speeds. In response to the needfor precise volumetric measurements, new commercial solutions combine 3Dlaser measurement systems with 2D visual inspection systems in order tomeet the progressively stricter visual requirements for packaged food and tooptimise food production processes. A series of solutions focus on meatportioning and quality assurance and there is an increasing need forinspection of traditional food processing such as baking, fruit and vegetablesorting. Colour systems can improve the contrast in 2D food inspection.

15. Development of a technology of two-beam laser welding and full-size tests of oil and gas transmission pipes

By AG Grigor Yants, AN and NV Grezev, IA Romanov, VI Kazachkov, FDNuriakhmetov, VN Goritskii and published by the Machine Vision Onlinemagazine in August 2006, downloaded through TIB Hannover athttp://www.tib.uni-hannover.de/en/.The authors developed a technology with two beams at IPLIT, the Institute of the Russian Academy of Sciences, in order to solve the problems generatedby the extreme hardness of the metal in the welded joints in pipe steels notsuitable for standard TU 14-3-1270-2001 and the cold Nordic temperatures (-60°C). The two beams are combined in a single vapour gas channel. Theexperimental results show that a range of distances can be maintainedbetween focusing spots. With an 8kW laser it is possible to weld 8mm

thicknesses with filler wire and 12mm without filler wire. The article describesthe different metallurgic structure of the welded joint areas and reports thatthe property of the metal in the condition of bi-axial loading is stable.

16. Fibre lasers: emerging in major markets

By Bill Shiner, published as an IPG Photonics Corporation technical papers in2005, downloaded athttp://www.ipgphotonics.com/tp_fibre_laser_markets/resource_technical_delivery.htm

The article describes modern commercial fibre lasers in terms of composition,types (single mode, continuous and modulated, Raman shifted, Q-switched,frequency doubled and tripled), output and wavelengths (from a few to adozen kilowatts with single mode lasers covering from UV through visible tonear-infrared spectrum), pumping and lifetime (high power diode bars andsingle emitter pump diodes, from 10,000h to 200,000 hours), cooling (air ortap water), and beam quality. The article reports on materials processing applications of fibre lasers (including automotive welding and cutting,sintering, marking, scribing, drilling and heat treating) and their advantages(constant beam profile, no warm-up, micron-sized spots, high speeds andweld penetration, compact size, wide range of applications due to thedifferent wavelengths, no maintenance).

17. Cost forecasting model for order-based sheet metalworking



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By A. Bargelis and M. Rimasauskas, published in Proceedings of Institution of Mechanical Engineers in 2005, downloaded through TIB Hannover athttp://www.tib.uni-hannover.de/en/.The article describes a cost forecasting method for order-based sheetmetalworking in a context of competition, falling prices and globalisation. Thearticle compares traditional manufacture (dies and presses) with rapid

manufacturing technologies such as CNC punching and laser cutting. Thearticle reports that the laser method has a margin of error between 1% and15.5% and that it is easily applicable. Moreover, it accelerates costforecasting for commercial offers by 2-3 times and can be applied in bothindustry and research processes.

18. A plan for productivity. Laser cutting and welding shops fight toughcompetition

By Charles Bates, published in Welding Design and Fabrication magazine in2005, downloaded athttp://www.weldingmag.com/323/Issue/Article/False/11005/The article reports on existing shops that invest in the latest technology and

automation and strive to improve the overall manufacturing process andinterpretation of customers needs. However, buying the most powerful andspeedy lasers is not the solution to all problems and job-shop capability isvery important in resolving a wide range of manufacturing problems andtranslating customer needs by involving them in the design phase.

19. Laser like focus. 2-D and 3-D laser cutting machines add value to shops

By Susan Woods in Cutting Tool Engineering magazine, October 2005,downloaded at http://www.ctemag.com/pdf/2005/0510-lasercutting.pdf.The article reports on the main industries that use commercial 2D and 3Dlaser cutting, i.e. automotives (about 50%-60%), agricultural and constructionmachinery, aerospace and steel processing centres, and the medical industry– this last being a new outlet. Users range from small-shops to Tier 1producers or automotive makers. The text describes some basic elements of laser cutting such as materials (mainly mild steel, aluminium, stainless steeland titanium), thicknesses and cutting speeds (for 2D: up to 48.26mm/s with0.5mm-3mm thickness on steel, for 3D: 18mm in mild steel, 6mm inaluminium, 8mm in stainless steel and titanium), tolerances (mostmanufacturers hold ±0,0508mm to ±0,1016mm in sheet metal), and gasassistance. It reports on the advantages that make lasers worth theinvestment (no tooling costs or changes, no tool wear, repeatability, littlefixturing, finer finishing, touch free, and flexibility).

20. Very focused

By Andy Sandford in the Metalworking production magazine in October 2005,downloaded at http://www.ctemag.com/pdf/2005/0510-lasercutting.pdf.The article provides information about the Association of Industrial LaserUsers, on its 10th anniversary. The association originated in a EU Eurekaproject in the early 1990s and disseminates information from the countries of Europe, organises seminars on laser applications, deals with enquiries andquestions about aspects of laser processing and works to educate thesubcontracting industry that lasers can be used in small job shops as well asbig organisations.

21. Impact of industrial needs on advances in laser technology

By Paul Denney, published in the Critical Review: industrial lasers andapplications. Proceeding of the SPIE vol. 5706, in 2005, obtained via TIBHannover at http://www.tib.uni-hannover.de/en/.



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The article reports on the diffusion and acceptance of lasers for cutting,drilling, heat treating, welding, etc. The most popular applications are CO2 andNd:YAG, which have proved useful in almost all types of manufacturing facilities. The barriers to their acceptance are: efficiency, maintenance,investment cost, facility costs. Technological limitations will prevent lasersfrom undergoing radical innovations, and new developments (fibre lasers,

disc lasers) will progressively replace them. New applications will bedeveloped such as 3D remote welding, micro-welding and micro processing,portable processing. The article provides cost benchmarks.

22. Trends in laser material processing for cutting, welding, and metal depositionusing carbon dioxide, direct diode, and fibre lasers

By Wayne Penn in the Critical Review: industrial lasers and applications.Proceeding of the SPIE vol. 5706, 2005, obtained via TIB Hannover athttp://www.tib.uni-hannover.de/en/.The article predicts trends in CO2 and Nd:YAG lasers and the newer fibrelasers, highlighting that these last, although representing a quantum shift, arenot expected to replace the previous two lasers in certain industrial

applications (CO2 because of its safer wavelength and lower investment costand Nd:YAG because of its high power pulse). The article describes the typesof CO2 (conventional, axial and transverse flow, diffusion cooled) and diodelasers and fibre lasers. Cutting, welding and metal deposition applications areanalysed in relation to both technologies and future trends are discussed.

23. Fabrication of 3-D components by laser aided direct metal deposition

By Jyotirmoy Mazumder, Huan Qi and published in the Critical Review:industrial lasers and applications. Proceeding of the SPIE vol. 5706, 2005,obtained via TIB Hannover at http://www.tib.uni-hannover.de/en/.The article describes the Direct Metal Deposition system, which can fabricatethree dimensional components directly from CAD drawings by delivering various powder metals through the laser nozzle. The system eliminatesintermediate machining and considerably reduces final machining. Theinteraction between the laser and the metal powder allows the material’smicrostructure to be tailored or new materials with advanced properties to becreated. Key application parameters are build rate and envelope, the ability tomake parts out of different materials, dimensional accuracy and minimumfeature size. The system was first commercialised in 2005, can be integratedin currently available CNC machines and requires continuous correctivemeasures to maintain tolerances and acceptable residual stresses. Keyconclusions are the importance of integration between design andmanufacture and the possibility for remote manufacturing.

24. Development and trends in laser welding of sheet metal

By F. Vollertsen, published in the Advanced Materials Research Volumes 6-8of Trans Tech Publications in 2005, obtained via TIB Hannover athttp://www.tib.uni-hannover.de/en/The article reports on the potentials for reduction of distortions and hotcracking in laser welding by types of materials: thin materials, steel to steel,steel to copper, brittle materials, thick sheets. It also discusses some aspectsof fluid dynamics and alloying using filler wire. Laser welding in the last 20years has undergone remarkable progress, technologies offer continuouswave and pulsed solutions for different applications, the gain medium hasmoved from CO2 to solid state, and the level of knowledge and expertise in

advanced processing techniques and metallurgy have helped to overcomesome former limitations.



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25. High-power fibre lasers – Application potentials for welding of steel andaluminium sheet material

By C. Thomy, T. Seefeld, F. Vollertsen and published in Advanced MaterialsResearch Volumes 6-8 of Trans Tech Publications, 2005, obtained via TIBHannover at http://www.tib.uni-hannover.de/en/.

Fibre laser power is scaleable to 10kW with excellent beam quality. Highpower fibre lasers are energy efficient, have a long lifetime, and are smallwhich have made them a viable alternative to solid state and CO2 lasers formany applications. The authors tested a fibre laser, a Nd:YAG and a CO2 laserof comparable power for steel and aluminium welding. The fibre laserperformed well, with improved welding speed and ability to cope with thicksheets, especially welding with solid state lasers.

26. Small devices manufacturing by copper vapour lasers

By S. G. Gorney, I. V. Polyakov, M. O. Nikonchuk, published in Micromachining and microfabrication process technology, Proceedings of SPIE Vol. 5715,2005, obtained via TIB Hannover at http://www.tib.uni-hannover.de/en/.

The article describes the characteristics of copper-vapour lasers in theproduction of stents and other precision cut micro-components, whoseproduction requires low beam divergence, little treatment and heat treatmentzone, high accuracy and economic efficiency. The copper-vapour laser isbetter suited to these applications than other small wavelength lasers suchas solid state or Excimer lasers. They can also be used to cut most materialsi.e. metals and alloys, semiconductors, ceramics, wood, graphite, and to treatquartz. The main limitation is related to thickness, which should not exceed500μm. Their large size and time needed to prepare them for operationmeans that they are not widespread.

27. Fabrication flexibility. At Work in Brazil’s ‘no-till’ zone

By the OEM Finn-Power, published in Tooling and Production magazine, 2004,downloaded athttp://toolingandproduction.com/archives/1104/1104fabrication_flexibility.asp.This article reports on the use of a laser work centre in a market leading Brazilian group that produces highly vertically integrated no-till seeding equipment for agriculture. Lasers support the company’s need for flexibility(2,000 components were previously outsourced) with linear motors and aflying optics system with a working area of 3,000mm x 1,500mm x 100mm,which processes mild steel 6mm thickness and aluminium 3mm thickness.The group has equipped the system with automatic loading and off-loading devices and operates 3 shifts per day, 7 days per week complying with the

daily, weekly and monthly maintenance schedule.

28. Let there be light

By John Excell, published in Design Engineering magazine in 2004,downloaded at http://www.listechnology.com/DesignEngineer-060404.htmThe article is based on an interview with the director of an aerospacemanufacturing research centre who states that laser technologies brought anew manufacturing era due to their unprecedented complexity, strength andlow weight structures. At the heart of the spin-off company that he registeredis the development of a technique known as laser induced super (LIS)plasticity to create a working cell completely based on lasers. LIS can createthe strongest known form of metal joints with homogeneous joining, and no

residual stresses. According to the interviewee, lasers will replaceconventional machine tools in a huge number of machining facilities.

29. Machine vision guides lumber cutting



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By Yvon Bouchard, Philip Colet, published in Laser Focus World in 2004,downloaded athttp://www.laserfocusworld.com/display_article/202939/12/ARCHI/none/Feat/Machine-vision-guides-lumber-cutting The article describes application of lasers for a vision system used to optimiselumber cutting, and gives examples of how decreasing costs and increasing

ease of use and interfacing of vision systems enables the practical industrialnetworking of vision and robotic systems. Key issues for competitive lumbercutting are: reducing overheads and cutting errors, correct classification of woods, yield optimisation, i.e. greater precision and speed. An OEMincorporated machine-vision system is incorporated into its sawmill plantsthat are equipped with cameras. Once the image is acquired, a specificsoftware and 2-80 lasers for triangulation (lasers project multiple lines of lightas the log comes down the arc) elaborate the information obtaining the bestyield cutting configuration, which is transmitted to the mechanical saws.

30. Material processing with fibre lasers

By Ruediger Hack, published in Industrial Laser Solutions magazine in 2004,

downloaded athttp://ils.pennnet.com/display_article/167291/39/ARTCL/none/none/Material-processing-with-fibre-lasers/The article reports the advantage of fibre lasers in marking, micro-bending (for the hard disk industry) and micro-cutting applications (for the medicaldevices industry). Other applications are annealing, selective soldering,graphic arts. The main advantages are: high reliability, maintenance-free, highwall-plug efficiency, compact design, easy-to-integrate beam delivery, cooler-free operations, small floor space, and beam delivery distances of up to 7m.Fibre lasers are of particular interest for applications that need a smallfocused spot and high power density, e.g. 100W can be focused to 5 micronsdiameter with a brightness of more than 109 W/cm2.

31. CO2 lasers make the cut

By Holger Schülter, published in Photonics Spectra magazine, 2003,downloaded athttp://www.photonics.com/printerFriendly.aspx?contentID=66470This article reports the advantages of lasers versus plasma, waterjet andpunch-presses in flexible cutting and in particular of CO2-laser technologiesfrom the OEM’s point of view. Although CO2 lasers can offer power in excessof 20kW, optimal power is 5kW predicting a factor of +1kW every 5 years. Thearticle benchmarks commercial solid state lasers with CO2 lasers, whichrequire an investment 2-3 times smaller and unrivalled cost per Watt, whilethe former have much more flexible beam delivery conditions. The text reportsthe importance of development of optics and of accurate CO2-lasermanufacturing and assembly in order to avoid harmful oil or solid-particlescontamination in the fast rotating turbo radial blowers, which ensure highpower to the equipment.

32. Fibre lasers grow in power

By Valentin Gapontsev and William Krumpke, published in Laser Focus Worldmagazine, 2002, downloaded athttp://www.laserfocusworld.com/display_article/151027/12/ARCHI/none/Feat/Fibre-lasers-grow-in-powerThis article is about the evolution and characteristics of fibre lasers, invented

in 1963. Power has grown from a few milliwatts to 4W thanks to the cladding pumping by high-power multimode diodes described in the article, which alsodescribes the function of the fibre laser. The advantages of these types of lasers are high efficiency, compact dimensions, lifetime (30,000 hours vs



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10,000 for solid state lasers), no necessity for air-cooling or maintenance. In2000 power increased to 100W through addition of a multi-fibre side coupling technology and, because of its brightness, it can be used for welding,sintering and low-power brazing. Other advantages of fibre lasers are relatedto the insensitiveness of the beam quality to the power operating point andthe possibility to transport the output for distances up to 100m. Combining

the output of several 100W-lasers, the OEM could scale up to 2kW suitablefor automotive welding, and even to 10kW.

33. Towards real-time quality analysis measurement of metal laser cutting

By Cesare Alippi, Vincenzo Bono, Vincenzo Piuri, Fabio Scotti, published in theVIMs 2002 International Symposium on Virtual and Intelligent MeasurementSystem Proceedings, 2002, downloaded athttp://www.photonics.com/printerFriendly.aspx?contentID=66470The article describes an automated system for real-time quality monitoring inlaser cutting applications, for high-tech steel manufacturing industries.Because of the sensitivity to even small variations in the metal reflectivity,roughness, and oxidation and other risks such as metal eruption on optics

because of source instability, the reproducibility of laser metal welding process could be affected and off-line inspections would not detect this. Theresearchers developed a method based on digital image sequences of thesparks generated during the cut, which can be used to estimate quality byanalysing the angle of the sparks and the cutting parameters (speed, typeand thickness of metal, laser type). The results are categorised as acceptable,not acceptable, not classifiable with a mean classification error of about0.18%.

34. ICS lectures on industrial application of lasers

By N. U. Wetter, W. De Rossi, F. Grassi, W.M. Steen, Spero Penha Morato,published by ICS UNIDO in 2000, obtainable from ICS UNIDO or athttp://www.unido.org/en/doc/4490The text in this book is part of a training package developed by ICS UNIDOwith the goal of examining and describing the most common types of lasersused in industry, and providing some basic scientific background. The variousareas of industrial laser applications (cutting, welding, drilling, marketing andscribing), as well as the all-important subject of the laser market, are coveredin detail in its seven chapters. The laser applications described are tailored tothe objectives of the high-tech industrial sectors of Latin America, and focuson the expanding endogenous capacity in the laser field in that region.

35. Laser applications in the electronics and optoelectronics industries in Japan

By Kunihiko Washio, presented at the SPIE conference on laser applications

in microelectronic and optoelectronic in January 1999, downloaded athttp://www.photonics.com/printerFriendly.aspx?contentID=66470The paper discusses current status of and technological trends in lasermaterial processing applications in the electronics and optoelectronicsindustries in Japan. The article describes typical applications (semiconductordevices, display devices, circuit components, peripheral devices, energydevices) by types of laser (Q-switched solid-state lasers, pulsed Nd:YAG, XeClExcimer, pulsed CO2, KrF or ArF Excimer). Representative applications arephotomask repairing, lithography, memory repairing, annealing, marking,trimming, drilling, patterning, and welding for products ranging from mobilephones to laptops, memory chips, to solar cells.

36. Laser cutting: industrial relevance, process optimisation and laser safety

By H. Haferkamp, M. Goede, A. Von Busse, and O. Thürk, presented at theopto-contact workshop on technology transfers, start-up opportunities and



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strategic alliances, Québec, Canada in 1998, obtained through TIB Hannoverat http://www.tib.uni-hannover.de/en/.The paper tackles two aspects of laser cutting: integrated quality controltechniques and environmental safety and health. It describes local highresolution thermo-graphic measurement of the temperature distributionwithin processing zones as a way to monitor process quality. Concerning

safety, the hazards involved in laser cutting are outlined: varying emissionrates with a complexity of air contaminants of which 90% are highlybreathable, and 40%-60% of which may remain in the alveoli. The articledescribes different filtration systems, depending on the application and thematerials: cyclones, electrostatic filters, surface filters, adsorption,absorption, combustion, biological filtration.

37. High power fibre lasers

By V.P. Gapontsev; L.E. of the Institute of Radio Engineering and Electronics;USSR Academy of Science, 1991, obtained through TIB Hannover athttp://www.tib.uni-hannover.de/en/ and downloadable athttp://adsabs.harvard.edu/abs/1991assl.proc..258G .

The article describes a study on the possibility of increasing the output powerof fibre lasers by tens of watts and compares the advantages of these withsolid state laser: high optical damage threshold of quartz fibres, high singlepass gain, minimum forced water cooling or air cooling for power less than10W, insensitivity to stresses due to temperature gradients typical of solidstate, low level of losses in the quartz fibres. The article forecast thecompetition from fibre lasers vs high-power crystal lasers in severalapplications with simple, compact, reliable and low-cost devices.



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Part 2. Lasers in the future: perspective for small

and medium enterprises



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SUMMARY

1 LASERS - THE WAY FORWARD......................................................................58

2 ADVANCEMENTS IN LASER SOURCES AND PROCESSES ...........................58

2.1 LASER sources improve and become more available ........................60

2.1.1 Evolving laser source schemes ....................................................612.1.2 Semiconductor power lasers........................................................61

2.1.3 Fibre lasers ....................................................................................65

2.1.3.1 CW fibre lasers status and perspective ......................66

2.1.3.2 Pulsed fibre lasers..................................................69

2.1.4 CO2, solid state, gas lasers...........................................................70

2.2 New interaction mechanisms...............................................................72

2.2.1 Exploiting a better beam quality ..................................................72

2.2.2 Novel processes based on short pulses......................................73

2.2.3 Improved versatility of laser sources ...........................................73

3 HOW RESEARCH CAN INFORM SMEs ..........................................................75

3.1 Direction of laser research ...................................................................753.2 Some examples of future developments ............................................75

3.2.1 Solar-pumped lasers.....................................................................75

3.2.2 Versatile microchannel drilling in transparent media ................76

3.2.3 The silicon laser ............................................................................76

4 CONCLUSIONS...............................................................................................78

REFERENCES.........................................................................................................79



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List of Figures

Figure 1. Dr. Theodore H. Maiman and the scheme of his ruby laser. 58Figure 2. Set-up for automated laser welding of luer-lock pipes forapplication in the production of sterile components. The laser improves

welding by enabling a contactless process, with high speed and fullattainment of product specifications. Think Laser (Italy)

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Figure 3. Optical power of mounted bars has grown at a compound rate of about 15%. This may continue toward the kiloWatt per bar5.

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Figure 4. Structure of a semiconductor or diode laser, with indication of the layers to obtain the double heterostructure6.

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Figure 5. Typical relation between a beam irradiated by a semiconductorlaser near the emitting surface, near field, and farther field. Typical valuesof the near field size are 1 µm x few tens up to few hundreds of µm, whilethe angular extension of the far field is about 50° in the fast axis (verticalin the scheme) and a few deg. in the slow axis.

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Figure 6. Single emitters semiconductor lasers, 6 W CW out of a 200 m

x 1 m active area. Emission available at different wavelengths including 808 and 840 nm. Footprint size is approx 6X10 mm. Spectra Physics –Newport (USA) www.newport.com

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Figure 7. Typical arrangement of a semiconductor laser bar, with theparallel emission of many emitters

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Figure 8. High power (60 W CW, 808 nm) semiconductor laser bars: fastaxis collimated (right) or not (left). The difference is the cylindrical lensfixed in front of the emission area. The electrical connections are thescrews on top of the component. The footprint size is DILAS (D)www.dilas.de

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Figure 9. A pair of wavelength-multiplexed stacks (each consisting of threesets of bars at different wavelengths) is spatially offset by half of the barseparation for spatial interleaving. Spectra-Physics (USA) and University of Southampton (UK).

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Figure 10. Miniaturised power semiconductor lasers: the left and centreones with surface mount (TO 220 package) the right with the C-mount.Osram (D)

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Figure 11. The scheme of a power fibre amplifier 65Figure 12. The fibre laser with several pump lasers connected, to generatehigh power beams

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Figure 13. Pump module assembly for high power fibre laser. IPG (Oxford,MA USA)

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Figure 14. High power fibre laser unit: assembly of the pump modules andthe fibre resonator, IPG (USA)

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Figure 15. A fibre laser oscillator in operation, Laser Zentrum Hannover(Germany)

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Figure 16. Pulsed fibre laser in Q-switched operation, typically for marking applications, IPG (Oxford, MA USA – left), SPI (Southampton, UK - right)

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Figure 17. An ultrafast fibre laser (left) and the setup for its use inmicromachining. Laser Zentrum Hannover24 (Germany)

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Figure 18. KiloWatt size CO2 lasers. Semilsealed type, left ElEn (Italy) anddifusion-cooled, right Trumpf (Germany)

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Figure 19. Examples of state-of-the-technique station for manual welding and molding repair, Sisma (Italy)

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Figure 20. Principle of a kiloWatt Yb:YAG disk laser, pumped bysemiconductor lasers. Rofin (Germany)

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Figure 21. Beam parameters product BPP as a function of emitter powerfor different laser sources, IPG (USA)

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73



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Figure 22. Different finishing for cuts operated on a 1mm thick INVAR inthe nanosecond regime, 8 ns, 0.5 mJ per pulse (right) and femtosecondregime 200 fs, 0.5 mJ per pulse (left) , Clark (Canada)Figure 23. Laser welded automotive light and particular of the weldedarea, Think Laser (Italy)

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Figure 24. Solar powered Cr-Nd:YAG laser 75

Figure 25. Fabrication of microchannels in fused silica with circular crosssection femtosecond pulses, (a) end-face microscope image of a row of microchannels and (b) SEM image of one of them.

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Figure 26. Scheme of an ultrafast silicon laser 77



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ACRONYMS

ABS Acrylonitrile butadiene styrene plasticCAD Computer Aided DesignCAM Computer Aided Manufacturing CNC Computer Numerical ControlCO Carbon MonoxideCO2 Carbon Dioxide gas – used also as laser medium for mainly

industrial high-power useCW Continuous WaveEr:YAG Erbium-doped Yttrium Aluminium Garnet, laser medium mainly

for medical useFAC Fast Axis CollimationHAZ Heat affected zoneHeNe Helium Neon laserLASER Light Amplification by Stimulated Emission of RadiationLCD Liquid crystal displayLIS Laser Induced Super PlasticityMAG Metal Active GasMIG Metal Inert GasMPE Maximum Permissible ExposureN2 Nitrogen gas – used also as laser mediumNd:YAG Neodymium-doped Yttrium Aluminium Garnet, laser medium for

industrial, medical and scientific applicationsOEM Original Equipment ManufacturersPC Personal computerPET Polyethylene terephthalate plasticPVC Polyvinyl Chloride plasticQC Quality Control

R&D Research and DevelopmentSAC Slow Axis CollimationSME Small and Medium Enterprise/sTIG Tungsten Inert GasTm-fibre Optical fibre with core doping of Tulium element, laser medium

mainly for medical use Yb-fibre Optical fibre with core doping of Ytterbium element, laser

medium mainly for industrial use



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1 LASERS - THE WAY FORWARD

The capacity of lasers to generate new industrial solutions, new processes and to bemore financially viable has been proven. The first laser, produced by Theodore H. Maimanon 16 May 1960 at the Hughes Research Laboratory in California, was a remarkable

scientific achievement, following four decades of effort and discovery. Maimanintroduced this new device to the world. He used the technique of shining a high-powerflash lamp on a ruby rod with silver-coated surfaces.i However, its introduction met withsome strong opposition. Charles H. Towner, who pioneered masers and lasers wasawarded the Nobel Prize for his efforts, in 1964, He reported that initially ‘many peoplesaid to me—partly as a joke but also as a challenge—that the laser was "a solution looking for a problem"’.ii

Figure 1. Dr Theodore H. Maiman and his scheme for a ruby laser iii

The introduction of the lasers was hampered by the complexity and fragility of the earlydevices, often based on expensive and unfamiliar components. The barriers reduced asthe applications and versatility of lasers improved and expanded. More companies began

to produce lasers and more mechanisms were invented for laser light exploitation. Morenovel products were produced that previously had not been possible and a virtuous circlewas set up, which turned what many had thought of as a scientific marvel into acommodity.

The international market for lasers and their components is now very mature. Lasershave brought a number of functions to everyday activities such as bar-code readers, DVDand CD readers in computers, music/video players, screen pointers, pollution analysersin towns and cities, and optical rulers and range meters, which have become universallyaccepted.

Here we examine the current and future state of laser technology and point to areaswhere developments in laser sources and applications could be effective and profitablefor SMEs and entrepreneurs looking to progress their business. As good information andthe capacity to forecast the economic evolution of an industrial sector is crucial in thedecision-making process, we hope that this work will be informative and improveunderstanding of the present and future opportunities related to laser technologies.

2 ADVANCEMENTS IN LASER SOURCES AND PROCESSES

It is necessary to understand that envisaging a new application for laser technology is theoutcome of a series of questions deriving from the context of the application. The spur forenvisaging a new technique can include:



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• reducing processing times in order to increase production rates. This isstandard process-innovation;

• exploiting a new interaction mechanism to improve the state-of-the-technique,e.g. to reduce the side-effects of a welding process, or the heat transfer in thedrilling process of a delicate biological membrane;

• improving general performance of a production system, e.g. by using a roboticarm for laser beam delivery and operation in relatively small work stations;

• reducing the cost of the production process by avoiding complex systems orby reducing the space required for the production station or by significantlyreducing the costs of the process station, the power supply, the recycling of associated components, or the disposal of production rejects.

Figure 2. Set-up for automated laser welding of luer-lock pipes for application in the production of sterile

components. In this case, the laser improves the welding because it enables a contactless process, with

high speed and full attainment of the product specifications. Think Laseriv (Italy)

To explain the role of the laser in an innovative production scheme, we need to focus on aseries of factors:

• what process is the laser needed for?

• what type of materials are used in the process and what are theirthermal/optical/chemical characteristics, in order to define the interactionparameters?

• what are the specifications for the laser source, in terms of wavelength, typeof operation, CW or pulsed, average/peak power, pulse duration, etc.?

• what are the specifications for the system that guide the light to the pointwhere the process occurs?

• what are the specifications for the optical system that delivers the radiation,

as the focusing unit or the collimator?• does the business plan for the laser solution indicate convenience with

respect to a traditional solution?



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This last point has to be seen in the perspective of the expected lifetime of the newtechnology, and an estimate of production development. It is separate from the technicalaspects listed, but equally important. In choosing the most appropriate laser technique,the technical and economic experts need to have equal input.

Figure 3. The optical power of mounted bars has grown at a compound rate of about 15%. This may

continue towards the kiloWatt per bar5

2.1 LASER sources improve and become more available

The evolution of the laser market has provided opportunities for SMEs. In semiconductorlasers, the price per watt has decreased from $2,000/W in 1987 to some $25/W in2006 for high power bars,v and to some $6/W for fibre-coupled diodes, according to IPGPhotonics (Oxford, MA).vi These components are the basis of many laser applications andare the pump sources for fibre lasers and most solid state lasers including versions of Nd:YAG lasers.

In addition to decreasing costs, the capacity to generate more and more power (depictedin Figure 4) has increased allowing reductions in the size of the laser source, making itsimpler and easier to mount on a compact station. Solutions once considered tooexpensive for SMEs are now viable.Below we review some laser source developments, driven by the research. We highlightthose that could be of interest to SMEs.



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Figure 4. Structure of a semiconductor or diode laser, with indication of the layers required to obtain the

double heterostructure

2.1.1 Evolving laser source schemes

Developments in laser sources are aimed at increasing simplicity, wall-plug efficiency (theratio of emitted over absorbed power including chilling), reducing production costs andmaintenance requirements, and increasing ease of integration in process systems. Inmost cases, these aspects have been addressed very effectively and to an extent wereunforeseen only ten years earlier.

2.1.2 Semiconductor power lasers

The high power semiconductor, or diode, laser is maybe the most important type of lasercomponent due to its versatility and reliability. Initial difficulties were related to thethermal damage induced by absorption of the side of the laser beam inside the medium,and the high dissipation resulting from the emission. The first aspect was addressed verysuccessfully by adding a near-transparent surrounding to the active medium, as depictedin Figure 5, which shows the double heterostructure,vii which provides thisproperty.viiiImproved efficiency came from the remarkable progress made in the process

for manufacturing the layer structure, which resulted in a very pure laser medium.



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Figure 5. Typical relation between the beam irradiated by a semiconductor laser near the emitting surface,

near field, and far away, the far field. Typical value of the near field size are 1 µm x few tens up to few

hundreds of µm, while the angular extension of the far field is about 50° in the fast axis (vertical in the

scheme) and a few degrees in the slow axis.

Laser beams are now very asymmetric, due to the large difference in the extension of thelaser’s gain medium in the direction normal to the junction and that parallel to it (seeFigure 6).

Figure 6. Single emitters semiconductor lasers, 6W CW out of a 200m x 1m active area. Emission available

at different wavelengths including 808 and 840nm. Footprint size is approx 6X10mm. Spectra Physics –

Newport (USA) www.newport.com



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The direct use of the radiation is quite limited for the rapid spread of the radiation, whichcauses a corresponding rapid decay of laser intensity along the emission axis. In order tolimit this phenomenon, a lens to reduce the fast axis divergence is often included in thelaser source. A second lens, which in some cases can be combined with the first, can beintroduced to achieve collimation of the slow axis. In the mid 1990s high power laser barsbegan to be produced by combining a series of emitters (see Figure 7).

Figure 7. Typical arrangement of a semiconductor laser bar, with the parallel emissions from many emitters

A fast axis divergence lens can be used to collimate these emissions and exploit a systemfor shared aperture component (SAC). Application of the radiation from the bars requiresequalisation of the beam parameter product (BPP) parameters along the slow and fastaxes.

Figure 8. High power (60W CW, 808nm) semiconductor laser bars: fast axis collimated (right) or not (left).

The difference is the cylindrical lens fixed in front of the emission area. The electrical connections are the

screws on top of the component. The footprint size is DILAS (D) www.dilas.de

The above described operation was achieved using different optical layouts. A solutionusing the step-mirror design was introduced by Keming Du and co-workers at theFraunhofer Institute for Laser Technology, Aachen, Germany. ix A different but also veryeffective solution exploiting micro lenses was introduced by the LIMO-LissotschenkoMikrooptik, Dortmund, Germany.x There are other schemes that use different geometriesof planexi or concave mirrors.xii The technique for this power emission and handling using laser bars and beam shaping optics has achieved several hundreds of Watts of power from a single fibre.In applications where the process uses more than one wavelength, the combinations of

bars each emit on a different wavelength which are joined using dichronic mirrors. Anexample of a beam combiner using high power bars is given in Figure 9.



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Figure 9. A pair of wavelength-multiplexed stacks (each consisting of three sets of bars at different

wavelengths) is spatially offset by half of the bar separation for spatial interleaving. Spectra-Physics (USA)and University of Southampton (Southampton, England)

The life of semiconductor lasers has increased by several orders of magnitude andexpected values in normal laser operations are now some 10-50,000 hours forcontinuous-wave (CW) devices and several billion shots for pulsed lasers.

The future for semiconductor lasers looks promising:

- the efficiency of radiation generation is increasing steadily. A US DARPA-fundedproject, Super High Efficiency Diode Sources (SHEDS), is working on achieving

values of 80% of the ratio of electrical to optical power.xiii

Several companies aremarketing a component with 60% efficiency, nearly 50% more than values twoyears ago. In addition to reduced absorption in supply power, the high efficiencyenables reduced dissipation. Reducing the power of the cooler, and its size andcost, makes thermal management of the source easier and cheaper. In addition tothe lower prices this will make many applications more attractive;

- cooling of the laser sources bas been improved through a novel technique for thetransfer of heat from the laser active element and the exterior. For example, amicro channel structure has been introduced,xiv to reduce thermal resistance anddeformation, improving laser operation;xv

- the packaging of the laser bars is simpler and more compact. CW lasers of a fewWatts power have been produced using surface-mount geometry, which indicatesthe direction towards the integration of the laser source inside the power supplywith a paramount change of the laser source concept. The diagram below (Figure10) shows some early examples of this development, for fibre-coupled or freespace sources. The C-mount standard in the last picture is an evolution of thesingle emitter laser with a reduced footprint of about 7x7mm.



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Figure 10. Miniaturised power semiconductor lasers: the first and second with surface mount (TO 220

package) the last with a C-mount. Osramxvi (Germany)

Semiconductor lasers are eroding ever larger shares of the market for traditional solidstate lasers for industrial applications. Based on their intrinsic simplicity of operation andrugged design, they are expected to expand in the future and especially in the context of technologies for SMEs.

2.1.3 Fibre lasers

The high power fibre laser is a recent development in industrial lasers and has someinteresting characteristics. Its scheme is directly derived from devices intelecommunication networks used to amplify optical streams of information along fibres.

This has eliminated the traditional scheme of detection, filtering and re-modulation of thepulses in long distance data links.xvii

Figure 11. The scheme of a power fibre amplifierxviii

Figure 11 depicts a fibre amplifier, which is the core of the fibre laser. The illustrationshows the double-clad fibre, which is one approach to pump-core coupling: the pump

pulse is a laser beam on the wavelength of the absorbing band of the specific laser gainelement. This is usually focused on the external guiding structure of the fibre (green). Theblue core at the centre of the fibre is where the laser active element is positioned. Theoptical pumping is achieved by the coupling of the pump radiation with the active core,along the fibre, as shown in the ray representation. The amplified beam is emitted fromthe core, with the divergence resulting from the guided mode. Other schemes weredemonstrated with interesting outcomes.xix The wall-plug-efficiency of high power fibrelasers has achieved 25% value in the case of ytterbium core, operating at 1,080nm.

Figure 12 shows the complete laser, including the semiconductor pump lasers coupledusing fibre connections.



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Figure 12. The fibre laser with several pump laser connected, to generate high power beamsxx

The powerful fibre laser is a synthesis of several independent achievements:

• powerful pump power sources provided by fibre-coupled semiconductorlasers;

• development of new schemes for coupling the pump and the active medium;

• introduction of reliable resonator mirrors inside the fibre, by means of periodic modulation of the fibre refractive index, such as a Bragg mirror;

• fabrication of high purity fibres, which reduce scattering and spuriousabsorption. This is crucial for the increased power needed to control failuresin the components.

Progress in this type of laser has paralleled the progress made in photonic crystal fibres,

whose versatile design enables a variety of linear and non-linear optical effects.xxi

The most important characteristic of the beam generated by a fibre laser is its superiorbrightness with respect to other sources of similar power. The internal core of the fibrelaser provides the laser radiation with a very regular (often near Gaussian) transverseprofile. The beam diameter in the fibre is similar to that in the core, which is a fewmicrometers for low- to mid-power lasers up to about 100W, and from 50 to 100µm forkiloWatt range lasers.

The table below indicates the laser elements, which are doped at the core for industriallasers and the corresponding wavelength range of the emissionxxii.

Element Emission range

ytterbium (Yb3+) 1.0-1.1 μmerbium (Er3+) 1.5-1.6 μm, 2.7 μm

thulium (Tm3+) 1.7-2.1 μm

This efficient and very small emissions area enables the radiation to be focused in orderto achieve higher intensities than obtained with solid state lasers of similar power. Theadvantages are discussed below.

2.1.3.1 CW fibre lasers status and perspective

CW fibre lasers are improving in terms of the power emitted and in the variety of wavelengths available.

As already mentioned, in order to increase the power, technological progress in fibreconstruction, reduction of impurities, increased pump power and stability, coupling of the



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pump to the core, etc. were required.xxiii The problems were related to non-linearabsorption and back reflection, due to the very high wave intensity inside the fibre, anddamage occurring at the interfaces, or the end face of the fibre.The current CW fibre lasers are comparable if not superior, in terms of maximum power,to traditional laser sources.xxiv Peak power can reach 50kW, according to IPG Photonics(Oxford, MA), bigger than the most powerful CO2 sources. Figure 13 depicts a compact

source using a kW ytterbium fibre laser. The pump lasers for this Yb:fibre laser are aseries of modules of single emitter semiconductor lasers, that are closely arranged (seeFigure 14).

Figure 13. Pump module assembly for high power fibre laser. IPG (Oxford, MA)



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Figure 14. High power fibre laser unit: assembly of the pump modules and the fibre resonator, IPG (Oxford,

MA)



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CW lasers are likely to experience significantly improved performance and widerapplication. The economic and technical advantages of these sources over moretraditional ones include higher efficiency, greater brightness or emitted power per unitarea of the emitter, and solid angle of emission, smaller size, and more convenient beamdelivery, via fibres that are tens or even hundreds of metres long. Their growth will causea reduction in the price per Watt, similar to that for semiconductor lasers.

Figure 15. A fibre laser oscillator in operation, Laser Zentrum Hannoverxxv (Germany)

2.1.3.2 Pulsed fibre lasers

Pulsed fibre lasers have not overtaken traditional Nd:YAG or CO2 lasers in terms of peakand average power.

Figure 16. Pulsed fibre laser in Q-switched operation, typically for marking applications, IPG (Oxford, MA -

left), SPI (Southampton, UK - right)



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The most popular application of pulsed fibre lasers is for marking surfaces, and forresistor trimming, drilling of small holes and similar micromachining jobs.

The compact size of the source, combined with its rugged construction makes it acandidate for low to mid power applications, about 20W, that require Gaussian profile

emitted beams. Another area of application is as a source of ultrafast duration pulses, i.e.durations of sub-picoseconds (1 ps = 1 10 -12 s) – or the femtosecond scale (1 fs = 10-15 s).

Figure 17. An ultrafast fibre laser (left) and the setup for its use in micromachining. Laser Zentrum

Hannover24 (D)

The technique used for the generation of these pulses is mode-locking, which is verycommon in crystal lasers.7 The implementation of fibre into this technique is complicatedby the relatively low threshold or non-linear effects, which negatively influenceperformance.xxvi There is very little demand from industry for ultrafast sources. However, greaterunderstanding of the potential offered by ultrafast processes enabled by these sources isexpected to increase their application.

2.1.4 CO2, solid state, gas lasers

The CO2 laser, for many years has been the industry standard for metal cutting andwelding. Its technology is mature and can be considered the benchmark for comparisonwith other newer sources.

Figure 18. KiloWatt size CO2 lasers. Semi-sealed type, left ElEn (Italy) and diffusion-cooled, right Trumpf

(Germany)



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Large power systems are usually only used by the heavy industries; the several hundredWatt to a few kiloWatt systems are the most attractive for SMEs. The demand foradvanced beam delivery for robotic welding, has highlighted the advantages of solid statelasers such as the cylindrical-rod Nd:YAG laser. The pumping schemes in these types of lasers are based on lamps that need to be replaced every few hundred hours of

operation, sometimes up to a thousand hours.This type of Nd:YAG laser is the standard for several applications requiring tens tohundreds of Watts of power. For SMEs with small to medium scale production, lasertechnology has brought advantages and success in several types of applications.

Figure 19. Examples of state-of-the-technique station for manual welding and moulding repair, Sismaxxvii (Italy)

For high power applications, these sources have been outperformed by a different type of resonator, based on an active disc-shaped medium. These lasers are attractive in termsof price per Watt for sources in the range of 1 to a few kW.

Figure 20. Principle of a kW Yb:YAG disk laser, pumped by semiconductor lasers. Rofinxxviii (D)



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2.2 New interaction mechanisms

The developments in laser sources are continually extending the range of tools availableto laser applicators. The more direct effect of these developments is the reduced priceper Watt.

These new sources are spurring competition by reducing processing costs. However,other interesting aspects are introduced with the sources, i.e. the power fibre lasers.There are also other benefits which need some further explanation.

2.2.1 Exploiting a better beam quality

The description of the high power fibre laser shows the laser beam is emitted from a verysmall active core. Numerical characterisation of the beam quality can be done by beamparameter product (BPP), i.e. the product of the beam source size (the radius wo)

multiplied by the far field half-angle of the beam θf , based on the following equation:

BPP [ mm • mrad ] = θf • wo = λ [ μm ] • M2 / π

where M2 is the quality factor of the beam and λ is the laser wavelength.xxix The values of interest to SMEs are plotted in the graph in Figure 21.

Figure 21. Beam parameters product BPP as a function of emitter power for different laser sources, IPG

(Oxford, MA)

A low value of BPP produces a focus on a small spot, with high intensity on the irradiatedarea. If the process is characterised by a threshold, e.g. in welding or marking processes,a low BPP reduces the specification of the source power to accommodate this process.This also reduces the area affected by the laser process. Therefore, a low BPP limits the

0.00

5.00

10.00

15.00

20.00

25.00

30.00

0 2 4 6 8 10 12 14

Power ( kW)

B P P

( m

m

x m r

a d ) BPP - CO2

BPP- Fiber Laser

Metal Cutting

Diode-Pumped

SS Lasers

Lamp -Pumped

SS Lasers



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HAF of the material, and preserves the original structure of the sample. The advantagesof a low BPP are significant, and are the basis of current laser source developments.

2.2.2 Novel processes based on short pulses

The action of the laser pulse in the case of a surface process, such as marking ortrimming, is achieved in tens or one-two hundreds of nanoseconds. This is the typicalregime of operation in Q-switched lasers. A variety of sources may be effectively operatedin such a regime at different operational wavelengths.

Figure 22. Different finishing for cuts operated on a 1mm thick INVAR in the nanosecond regime, 8ns,0.5mJ per pulse (right) and femtosecond regime 200fs, 0.5mJ per pulse (left) , Clarkxxx (Canada)

The investigation on the outcome of the process in the micrometre scale has shown thatin many cases it took place a significant interaction with the material close to theprocessed zone. The reason for this is that in this time scale the thermal conduction mayinduce a significant thermal cycle to this material, which results in evidenttransformations and even formation of micro-cracks.By repeating the above processes using sources emitting shorter pulses, as in the case of the mode-locked laser generating ultrafast pulses, the results differ. The much shorterpulse durations reduce the propagation of heat during the laser pulse, resulting in the

most efficient process. Ultrafast lasers have the fewest side effects and thus interest inthem is growing.

2.2.3 Improved versatility of laser sources

The change in technology from lamp-pumped to semiconductor-pumped lasers induced asignificant simplification of the laser source scheme and a reduction in its size and powerabsorption. Fibre delivery of medium to high power beams allows the integration of alaser source with a robotic arm or a similar device which operates on 3D targets.Figure 23 depicts the final welding of the rear-light of a car, in which the curved profilewas successfully welded using a 35W semiconductor laser. The joint involved clear and

opaque thermoplastic moulded parts. The laser beam was focused by an optics freelymanoeuvred by a robotic arm. The light robotic arm is sufficient in this case; in the caseof the traditional mirror path, a much larger and more complex device would be required



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Figure 23. Laser welded automotive light and particulars of the welded area, Think Laser (Italy)



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3 HOW RESEARCH CAN INFORM SMEs

Here we highlight some areas of research that are likely to affect the laser market in thefuture. From developments so far, it is clear that in the photonics area there is a veryclose link between the laboratory and the market.

3.1 Direction of laser research

The general direction of laser research is towards extending the limits of the currentstate-of-the-art. Lasers that are currently on the optical benches of research laboratorieswill be available in the market in a few years, indicating the speed of improvement in thepower of commercial lasers, stability in terms of output power, etc. There is great interestin the production of novel laser schemes, materials, pumping systems, operationalwavelengths and pulse durations.Researchers in Italy have perfected techniques to generate and measure optical pulsesas short as 130 attosecondsxxxi (1 attosecond (as) = 1 10-18 seconds), thus for the firsttime producing an artificial event shorter than the classical orbital period of the electronin the hydrogen atom. The results of their work will likely be exploited to devise opticaltools for the remote controlled induction of chemical bonds, which could also have animpact on industrial chemistry.

3.2 Some examples of future developments

A selection of results that could be of interest for future developments of SME-orientedlaser technologies are presented below.

3.2.1 Solar-pumped lasers

The idea of exploiting solar energy directly to energise laser pumping processes emergedin the mid 1990s.xxxii However, its application has evolved only slowly.

Figure 24. Solar powered Cr-Nd:YAG laser

The growing interest in developing renewable energy sources and in more energy-efficientprocessing, prompted a Japanese research group led by Prof. Yabe of the Tokyo Instituteof Technology to develop a laser pumped by solar radiation, used to induce an energy



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cycle without the use of fossil fuel.xxxiii Figure 24 depicts the system, which produced alaser output of 24.4W with a 1.3m2 Fresnel lens collecting solar light.xxxiv The researchersclaim that the system could achieve kiloWatts of laser output with a solar collector of some 7m2.This type of source could be used in many applications working flexibly according to theavailable solar energy Figure 24

3.2.2 Versatile microchannel drilling in transparent media

Microstructures in transparent media are required for many applications, such as micro-fluidics, drug-deliverys, micro-motors and filtering of liquids. The interaction of ultrafastpulses with doped glass enables the engraving of optical guides on glass. The researchgroup at the ULTRAS Laboratories in Milan, Italy, have produced such a guide on laseractive glass.xxxv

Figure 25. Fabrication of microchannels in fused silica with circular cross section femtosecond pulses, (a)

end-face microscope image of a row of microchannels and (b) SEM image of one of them.xxxvi

A further development involved producing a clear channel, a few tens of microns indiameter, in the glass, again with free choice of the shape and intersection of thechannels.This technique opens the possibilities for biophotonic devices integrating microfluidicchannels and optical waveguides in three-dimensional configurations incorporating novelfeatures.

3.2.3 The silicon laser

The possibility of transmitting information with light is limited by the emitters, lasers andLEDs, which are made of different materials from the usual silicon informationprocessors. Direct laser emission from silicon are impaired by physical properties andconsequently research into methods to make silicon-based devices suitable sources forshort pulses is very active.

Researchers at the University of California, Santa Barbara (UCSB) have produced a laserstructure on a silicon wafer,xxxvii which produces picosecond pulses at high rates of



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repetition, which is the essential characteristic of a source for integrated informationprocessing.

Figure 26. Scheme of an ultrafast silicon laserxxxviii

An electrically pumped, mode-locked evanescent laser on silicon has achieved fourpulses at multiple infrared wavelengths accompanied by 40GHz repetition rates. Thisdemonstrates that silicon lasers could significantly reduce the cost of lasers in numerousintegrated-circuit applications, and is promising for a wide number of applications.



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4 CONCLUSIONSThe price per Watt of laser light has been steadily decreasing and it is reasonable to thinkthat this will continue into the future.The advantages of lasers in manufacturing are manifold: many applications using lasersshow better quality, higher productivity and more opportunity for processing.

This report has demonstrated that there will be new opportunities in the near and longerterm future for entrepreneurs.



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REFERENCES

Reference books on lasers and optics:

1. O. Svelto, Principles of Lasers, 5th ed., Plenum Press 1999.

2. W. Koechner, Solid-State Laser Engineering, 6th ed., Springer 2006.3. A.E. B. Saleh and M.C.Teich Fundamentals of Photonics, John Wiley Series in Pure

and Applied Optics 2007.4. A. Siegman, Lasers, University Science Books 1986.5. E. Hecht, Optics, 4th ed., Addison-Wesley 2001.

General books on laser applications

W. M. Steen, Laser Material Processing, 3rd ed., Springer 2005.D. Schuoeker, High Power Laser in Production Engineering’, World Scientific, 1999.J. Powell, Laser Cutting , Springer 1998.

Laser Institute of America LIA Handbook of Laser Materials Processing, MagnoliaPublishing 2001.W. W. Duley, Laser Welding, John Wiley 1999.

In the indication of the references, the number in bolt type is the volume number and thefollowing one is the initial page of the article.

i Theodore H. Maiman, Stimulated Optical Radiation in Ruby, Nature 187, 493 (06 Aug 1960).ii Charles H. Townes, The first laser, from A Century of Nature: Twenty-One Discoveriesthat Changed Science and the World, Laura Garwin and Tim Lincoln, editors. TheUniversity of Chicago Press, 2007.iii http://timeline.aps.org/APS/Timeline/Middle.cfm?EventID=109iv Ch. 10 of W. M. Steen, Laser Material Processing, 3 rd ed., Springer 2005 andwww.thinklasersrl.comv M. Apter et al. High-power diode-laser bars come of age,http://www.laserfocusworld.com/articles/250394.

vi T. Hausken, Battle heats up between bars and single-emitter diodes,http://www.laserfocusworld.com/articles/266396.vii R. Diehl, High Power Diode Lasers, Springer 2000.viii O. Svelto, Principle of Lasers, 5th Ed., Plenum Press 1999.ix K. Du, M. Baumann, B. Ehlers, H.G. Treusch, P. Loosen, ‘Fiber coupling technique withmicro step-mirrors for high-power diode laser bars’, OSA TOPS, 10, 1997.x www.limo.dexi S Bonora and P. Villoresi, Advanced optics expand the applications of high power diodelasers, http://spie.org/x8699.xml and S. Bonora and P. Villoresi, Diode laser bar beamshaping by optical path equalization, J. Opt. A: Pure Appl. Opt. 9 441 (2007).xii S. Bonora, Compact beam-shaping system for high-power semiconductor laser bars, J.Opt. A: Pure Appl. Opt. 9 380 (2007).xiii http://www.darpa.mil/MTO/Programs/sheds/index.htmlxiv http://www.ilt.fraunhofer.de/eng/ilt/pdf/eng/products/Heatsinks.pdf xvhttp://www.laserfocusworld.com/display_article/255508/12/none/none/OptMN/Microchannel-cooling-ups-power-capacity-for-laser-diode-barsxvi http://catalog.osram-os.com/



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xvii E. Desurvire et al., Erbium-Doped Fibre Amplifiers, Device and System Developments,Wiley-Interscience, 2002.xviii C. Crossland, Thulium Puts Power Behind Eyesafe Fibre Lasers, NASA Tech Briefs,March 2007, and http://www.nufern.com/.xix A Tünnermann et al., The renaissance and bright future of fibre lasers, J. Phys. B: At.

Mol. Opt. Phys. 38 S681, 2005.xx V. Gapontsev et al., 2kW CW ytterbium fibre laser with record diffraction-limitedbrightness, Proc. Convergence on Lasers and Electro-Optics/Europe, Munich, Germany,2005 p. 508. and http://www.ipgphotonics.com/xxi J. C. Knight, Photonic crystal fibers and fiber lasers, J. Opt. Soc. Am. B 24, 1661 (2007)http://www.opticsinfobase.org/abstract.cfm?URI=josab-24-8-1661xxii Rare-earth-doped fibers, Encyclopedia of Laser Physics and Technology, http://www.rp-photonics.com/rare_earth_doped_fibers.htmlxxiii J. Limpert et al., 500 W continuous-wave fibre laser with excellent beam quality,Electronics Letters 39 645, 2003.xxiv Y. Jeong et al., Ytterbium-doped large-core fiber laser with 1.36 kW continuous-wave

output power, Opt. Express 12, 6088 2004,http://www.opticsinfobase.org/abstract.cfm?URI=oe-12-25-6088xxv http://www.laser-zentrum-hannover.de/en/fields_of_work/laser_development/fiber_laser.phpxxvi G. Agrawal, Nonlinear Fibre Optics, 4th ed., Elsevier 2006.xxvii Ch. 4 of W. M. Steen, Laser Material Processing, 3 rd ed., Springer 2005 andhttp://www.sisma.com/xxviii http://rofin.de/english/products/macro-laser/nd-yag-solid-state-lasers/disc-disk-laser-principle.phpxxix Ch 2 of W. M. Steen, Laser Material Processing, 3 rd ed., Springer 2005xxx http://www.cmxr.com/Industrial/Handbook/Chapter4.htm

xxxi G. Sansone et al., Isolated Single-Cycle Attosecond Pulses, Science 314 443, 2006.xxxii NREL Researchers Use Sunlight to Power Laserhttp://www.nrel.gov/news/press/1995/solar.htmlxxxiii T. Yabe et al., Demonstrated fossil-fuel-free energy cycle using magnesium andlaser, Appl. Phys. Lett. 89 261107 2006xxxiv T. Yabe et al., High-efficiency and economical solar-energy-pumped laser withFresnel lens and chromium codoped laser medium, Appl. Phys. Lett. 90 261120 2007.xxxv S. Taccheo et al., Er:Yb-doped waveguide laser fabricated by femtosecond laserpulses, Optics Letters 29 2626 2004xxxvi V. Maselli et al. Fabrication of long micro-channels with circular cross section using astigmatically shaped femtosecond laser pulses and chemical etching, Appl. Phys. Lett.

88 191107, 2006xxxvii M. Sysak et al., Experimental and theoretical thermal analysis of a Hybrid SiliconEvanescent Laser, Optics Express 15 15041 2007xxxviii B. Koch et al., Optics Express 15 11225 2007.



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10. laser technologies- a step forward for small and medium enterprises

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