str 2012 2 e complete

8/13/2019 STR 2012 2 e Complete

1/32

2/2012

PolymersPolymer production technology Customized foam manufacturing

New polymer pilot plant Flexible pumps for polymers

Solutions for the plastics industry Efficiency through coated tools Successful polymer analysis

Panorama World-famous in motor sports Insightful hot spots

8/13/2019 STR 2012 2 e Complete

2/32

New benchmarks for polymer technology

Dear Technology Professionals, Customers, and Partners,

Polymers are considered the material of choice for the cost-effective production of

mass products. However, the need for technically demanding solutions continues

to grow, so that many factors other than the material and manufacturing costs have

become decisive for success in the plastics market.

Plastics manufacturers are looking for flexible manufacturing processes in

order to be able to offer tailor-made products to their customers. The right mix

of raw materials and additives is just as decisive as the scalability, efficiency,

and controllability of the processes. Ecological aspects, such as energy con-

sumption, alternative raw materials, and degradability, play an increasingly

important role.

In this edition of the Sulzer Technical Review, you can find out how Sulzer is

setting new sustainable benchmarks for technological development in the polymer

industry.

Thanks to a significant investment, new polymer pilot installations and an expanded

test center are available to our clients in the process technology business. A number

of articles in this issue provide insight into our latest mixing and reaction technology

for polymers.

Because of the wide range of fluid properties needing to be processed, polymer

processes are a great challenge for pump technology. We will show you how our

pumps master these challenges with the greatest flexibility.Tools for the manufacture of plastic products require special surfaces. Our surface

technology division offers coating solutions and surface treatments for a multitude

of requirements.

Metrological analyses are essential in order to guarantee optimal plastic properties.

In this edition, you can read how we support our clients in polymer analysis and

solve even the most difficult cases with a detective-like flair.

I hope you enjoy reading these articles.

Klaus Stahlmann

CEO Sulzer

EDITORIAL

| Sulzer Technical Review2 2/2012

!

8/13/2019 STR 2012 2 e Complete

3/32

O5 ; +6=9:A scanning electron micrograph of polystyrene foam shows theair-filled hollow cells that make the material an excellent insulator.

Keystone / Science Photo Library / Eye of Science

CONTENT

Sulzer Technical Review |2/2012 3

Polymers

4 Flexible foam productionCustomized manufacturing of expandable polystyrene

8 Sustainable pumping solutions for polymer manufacturingFlexible and durable high-efficiency pumps for the chemical process industry

12 New bioplastics pilot plantInterview with Lorenzo Ghelfi, Sulzer Chemtech

14 More effective manufacturing through coated toolsEfficient processing of plastics

19 Spider silk as a superpolymerSulzer analogy

20 Following the trail of polymeric evidencePolymer analysisbetween measurement and interpretation

Panorama

25 Welcome to Sulzer Metco in LimogesSulzer world

26 Insightful hot spotsThermographic inspection of industrial gas turbine components

30 Events & News

31 Imprint

8/13/2019 STR 2012 2 e Complete

4/324376

The industrial polymerization of

styrene to polystyrene (PS) started

in the early 20th century and was

followed by the development of expan-

dable PS beads around 60 years ago. EPS

is a particle foam made by expanding

PS beads that contain a blowing agent

usually pentane. Steam heating causes

the beads to expand, and the final shape

is achieved by molding the pre-expanded

beads with steam and pressure. There

are numerous applications for EPS on

the market, and block and shape molding

are the most important conversion pro-

cesses currently employed to fabricate

foam products from EPS. In particular,

by using shape molding, various products

can be obtainedfor example, packaging

solutions, plaster, or sports equipment

many of which profit from customized

EPS formulations that add color or

mechanical properties.

Melt impregnation allows customized

production

In the common process chain, EPS resin

suppliers produce impregnated poly-

styrene resin granulates with the blowing

agent in large-scale industrial facilities.

The EPS is then sold to EPS molders.

They manufacture end productssuch

as packaging, construction material, or

drinking cupsaccording to customer

specifications.

Flexible foam productionThe properties of expandable polystyrene (EPS), one of the most important

foamed plastics in the world, can be significantly influenced by additives. Such

additives can repel insects, make the material flame resistant, or improve thermal

insulation. Sulzer Chemtech has developed a flexible process particularly suited

for the economical production of customized, special-grade EPS.

Sulzers EPS pilot plant allows process optimization, sample production, and feasibility testing for customers.

Customized manufacturing of expandable polystyrene


POLYMERS

8/13/2019 STR 2012 2 e Complete

5/32

Sulzer Chemtech offers a continuous

process for producing EPS granulates

from PS on an industrial scale of up to

100 000t per year (see STR 1/2009, p.6).

In this process, the melt is directly

impregnated with the blowing agent and

the required additives, and it is then sent

to an underwater pelletization process.

The melt impregnation has several

advantages over the conventional sus-

pension process. The product quality is

consistent and can be easily controlled,

as the additives and the blowing agent

are directly injected into the melt.

Environmental benefits and energy

savings

The environmental benefits include:

Lower water consumption

Straightforward recycling of excess

material

On an industrial scale, the hardware for

this process includes Sulzer Chemtech

static mixers and heat exchangers. In

particular, when connecting the Sulzer

EPS process directly to a polystyrene

melt plant, the static mixing approach

results in significant energy savings, as

the resin does not

need to be melted

again. This offers the

possibility of operat-

ing competitive styrene-to-EPS plants for

global-scale production of EPS commodi-

ties, for example, for innovative insulation

solutions. In fact, with the introduction

of a melt-based EPS process in the late

1990s by Sulzer, the technological basis

for the production of pigmented, flame-

resistant EPS for housing insulation was

established, and this gave rise to the

development of a number of innovative

materials using different additives.

Improving thermal insulation with

pigments

Several parameters, such as foam density,

choice of blowing agent, and cell size

distribution, can influence the thermal-

insulation properties of EPS foam. The

genuine advantage of EPS foam as insu-

lation material over competing insulation

solutions like polyurethane, mineral

wool, or extruded polystyrene foam

(XPS) is its low density and, hence, its

relatively low price. However, the insu-

lative properties significantly deteriorate

with decreasing density. Three mecha-

nisms contribute to the thermal conduc-

tivity of EPS (see info box):

Conduction

Convection

Radiation (mainly infrared).

With decreasing EPS density, the share

of infrared radiation strongly increases.

This effect can be avoided through pig-

mentation. Pigments, e.g., graphite, car-

bon, or aluminum particles, added to


POLYMERS

Low-lambda development

" ;94 +65

8/13/2019 STR 2012 2 e Complete

6/32

the EPS can absorb and/or reflectinfrared radiation and thus improve ther-

mal insulation1. This way, the insulative

property of low-density EPS can reach

the same level as EPS with a density two

to three times higher. Using optimized

mixing technology as well as the right

combination of additives in the process

leads to an improved dispersion of the

pigments in the final product and helps

to lower the additive consumption in

the Sulzer process compared to other

processes.

Meeting environmental require-

ments: alternative flame retardants

A disadvantage of using plastics in con-

struction is their flammability. Polystyrene,

in particular, burns readily and EPS foam,

unless equipped with flame retardants,

does not fulfill common building codes

relating to flame spread and smoke devel-

opment. Therefore, the material has to

be either used in combination with an

additional flame barrier on the side of

the construction method or impregnated

with suitable flame retardants. The most

widely used additive for this application

is hexabromocyclododecane (HBCD), a

highly brominated flame retardant with

more than 70wt% bromine per molecule.

HBCD has been the flame retardant

of choice in EPS for

several decades

now, because it is

very efficient: Typi-

cally, HBCD levels between 0.7 % and

3 % depending on the type of synergist

and process usedare required for

building insulation to reach the desired

flame retardancy. In particular, the use

of synergists imposes very efficient

temperature and shear control on the

production process. With decomposition

temperatures as low as 150C, as is the

case for commonly used peroxide

synergists, it becomes a prerequisite inmelt impregnation to cool and maintain

a low temperature and shear profile.

This factor has to be taken into account

for the design of mixers, extruders, and

pelletizers.

Flexible process allows the use of

HBCD substitutes

Recently, the toxicity and the environ-

mental impact of HBCD have become

matters of concern. Measurements have

shown that the material bioaccumulates

and biomagnifies so that several

environmental protection agencies

have put the chemical on their lists

of concerns. This development has

prompted the EPS industry to start the

search for a substitute for HBCD. Due

to its ingenious design and efficient

temperature control, the Sulzer EPS

process is much more flexible than classic

suspension technology as it allows

the use of new flame retardants currently

in development.

Defined distribution of particle sizes

The EPS quality is not only influenced

by the composition of the material but

also by the geometry of the molded beads.

An even, spherical shape of the beads

ensures the best particle fusion. The diam-

eter required for the EPS particles

depends on the intended use of the final

product. Different size classes are

typically defined for insulation, packag-

ing, food containers, or cups. And an

optimal mold fill is supported by a

narrow, uniform bead size distribution.

Together with Automatik Pelletizing

Systems, part of the MAAG group which

was recently acquired by Dover Corpo-ration, Sulzer Chemtech has further de-

veloped the existing underwater pelleti-

zation technology for stable production

of uniform EPS, in particular, EPS con-

taining pigments and flame retardants.

Due to its outstanding sphericity and pre-

cise pellet size distribution2, the product

can be processed like suspension product

without prior screening or sieving. Due

to a unique die plate design and efficient

heating, die freezing can be minimized

even for small bead sizes below 1mm.


POLYMERS

2 Prefoamed EPS beads from Sulzers EPS process show excellentsphericity and cell size distribution.

100m

1 mm

A* !1!*, $!ca $a! +" /$! b!a !*!

/$! b!/ a/c! "+*.

8/13/2019 STR 2012 2 e Complete

7/32

Premature foaming of the beads is

avoided thanks to pressure and temper-

ature control in the closed pelletization

water circuit.

Small-scale, economical production

The melt impregnation technology

represents a tremendous potential for

product innovation in the PS foam busi-

ness, not only on a large production scale

but also on a scale suitable for specialized

products. EPS converters, who are very

closely connected to end customers, typ-

ically have vast knowledge of the product

requirements and limitations of existing

EPS products for the applications they

serve. Unlike the big resin producers

with their commodity-grade EPS, con-

verters increasingly feel the need to differ

from their competition and to develop

niche products with special properties.

Because annual consumption can easily

reach 10000 t per year, the production

of their own EPS resin with a melt impreg-

nation plant suddenly becomes attractive,

in particular with PS resin widely

available at relatively low prices.

Simplified extruder process

Applying the in-depth process expertise

from a decade of EPS process develop-

ment, Sulzer Chemtech has developed

a second-generationEPS process suited,

in particular, to small-

scale production 3.

Using a combination of a twin-screw

extruder in which PS or EPS, blowing

agent, and all required additives are com-

poundedand Sulzers proprietary melt

coolers, the engineers have designed a

simplified manufacturing unit that is

attractive for smaller capacities of about

500 3000kg per hour. This extruder

process, the result of a joint cooperation

with the renowned German extruder

manufacturer Coperion, allows for the

economic production of EPS specialties

even on scales adapted to the requirements

of larger converters.

Sulzer supports EPS converters who

want to develop their own foam formu-

lations. They can produce and test cus-

tomized EPS grades with various addi-

tives in Sulzers pilot test facilities. The

clients benefit from the broad experience

that Sulzer Chemtech and its partners

have gathered with melt impregnation

technology.

Process innovation for the

environment

From the very beginning, Sulzer has

focused its process development on envi-

ronmentally friendly solutions for EPS

production. This designation encompass-

es two major areas: recycling capabilities

and the use of alternative blowing agents.

Because EPS is a lightweight, single-use

product with a decomposition time of

several thousand years in nature, the

end-of-life debate has always had a neg-

ative imprint on the product image. At

the same time, the commonly used blow-

ing agent pentane for foaming EPS has

a critical global warming potential and

falls under strict regulations in many

countries and legislations. While suspen-

sion polymerization is rather inflexible

in view of addressing these aspects, melt

impregnation offers a lot of room for

process innovation. Sulzer Chemtech

develops and offers technology for the

recycling of both unfoamed, impregnated

EPS from production (e.g., off-spec mate-

rial, unsold material from stock, etc.) and

compressed foam from consumer recy-

cling or production internal sources (cut-

off, blocks, etc.). Those materials can be

used as feed stream and be 100 % reuti-

lized for production of virgin EPS resin.

By using alternative blowing agents,

which do not fall under the regulations

of volatile organic compounds (VOC) yet

have similar properties to those ofpentane, converters can save significant

money on pentane abatement systems

and VOC taxes that may apply in some

countries. Development of these process

innovations is currently ongoing within

Sulzer Chemtech.


POLYMERS

3 Sulzers EPS process is suited for small-scale EPS production (5003000 kg/h).

P N5Sulzer Chemtech LtdSulzer-Allee 488404 WinterthurSwitzerlandPhone +41 52 262 50 22

[email protected]

S5! C$!/!c$ !1!+ a* +""!

/!c$*++#4 "+ /$! !c4c*# +" EPS.

Blowing agent

Polymer feed(PS, EPS,recyclate)

Additives(FR, pigments)

Gravimetric dosing systems

Twin-screw extruder (ZSK MEGA compounder) SMR melt cooler Gear pump

EPS micropellets

Underwater pelletizer

8/13/2019 STR 2012 2 e Complete

8/324377

The wide range of processes in the

polymer-manufacturing industries

leads to an extensive scope of pump-

ing necessities. It is essential to the oper-

ation of polymer plants that the process

pumps fulfill a variety of requirements.

In most polymer plants, pumps generate

the majority of energy cost. Therefore,

efficiencyof both hydraulics and elec-

trical drive is important. Another, even

more crucial, criterion is the reliability

of the pumps, because unplanned inter-

ruptions of the often-complex chemical

processes can cause significant cost

increases and environmental impact.

Pumping various fluids

With many installed units operating

globally, Sulzer s AHLSTAR series is the

worlds largest process pump series for

demanding industrial processes including

polymer processes. The capability to

work with all types of liquids makes

this pump range particularly suitable for

the challenging pumping operations

required in chemical processes. Whereas

the basics of pumping are the same in

all applicationsmoving a liquid and

increasing its pressurethe specific

parameters of the liquids to be processed

can differ dramatically. The fluids can

vary in viscosity or they can contain

fibers or solids.

Sustainable pumping solutionsfor polymer manufacturingIn the polymer-manufacturing industry, raw materials undergo chemical conversion during

their processing into finished products. These conversion processes very often require

conveying fluids with a wide range of characteristics. The liquids can be very hot or cold,

they may be chemically aggressive, or they can contain solids or fibers. With the AHLSTAR

process pump series, Sulzer meets the requirements of chemical process industries.

AHLSTAR pumps are designed for safe operation and easy maintenance and service.

Flexible and durable high-efficiency pumps for the chemical process industry


POLYMERS

8/13/2019 STR 2012 2 e Complete

9/32

Sulzer engineers had to consider all

those and more boundary conditions

when they designed the over ten different

impellers that make the AHLSTAR range

suited for almost every hydraulic require-

ment. Whether closed or open, dedicated

for low discharge, or wear-resistant,

impellers make it possible for the

AHLSTAR pumps to work with slurries,

clear, or contaminated liquids or fluids

containing solids of various sizes. These

process pumps can work at temperatures

of up to 260 C and pressures of up to

2.5 MPa, which is roughly equivalent to

the pressure 250 m

below water. With

the right choice

of materials, these

pumps operate corrosion free even

when handling liquids with extreme

pH values from 0 up to 14.

Exceeding international standardsInternational standards define sets of

minimum criteria that clients can expect

to be fulfilled by standard pumps.

Depending on the specification, the

following standards are applied to

centrifugal pumps:

API 610 (ISO 13709) standard for

demanding processes in the oil and

gas and hydrocarbon industries

ISO 5199 and ISO2858 (as well as

American standards ASME73.1) for

industrial processes

European standard EN 733 for light

industrial processes

The metric standard ISO 5199, for

example, covers the requirements for

pumps of back pullout construction as

used primarily in the chemical and petro-

chemical industries. It includes design

features relating to installation, mainte-

nance, and safety. Other codes define

main dimensions and operating ranges

of the pumps.

The pumps of the AHLSTAR series

fulfill ISO5199 and ISO 2858 interna-

tional standards relating, e.g., to dimen-

sions of flanges and base plates and,

therefore, do not require special effort

to install or maintain within existing

pipework. When it comes to performance

and quality, the pumps of the AHLSTARrange have extra features exceeding

the basic requirements and even sur-

pass the international standards

governing technical performance and

quality 1.

Solutions for liquids with high gas load

Conventional centrifugal pumps can han-

dle liquids with gas content below 4%,

but gas bubbles collected in the impeller

eye do impair pumping and will reduce

capacity and head. At a gas content of


POLYMERS

Non-Newtonian fluid behavior.

73

7984

88

91

93

79

73

66

Typical fluid properties in

polymer manufacturing

Viscosity is an important fluid property

that is relevant for pumping technology.

The viscosity describes a fluids resist-

ance to shear stress. Fluids like water

have constant viscosities and are

called Newtonian fluids.

Molten polymers and salt solutions

show non-Newtonian fluid behavior.

Their viscosity depends on the rate

of shear and can even be time

dependent.

1 The performance of theAHLSTAR pumps exceedsstandard requirements.

over 93%

efficiency

The shear-thinning behavior of poly-

mers (also known as pseudoplastic

behavior) means that the viscosity

becomes smaller if the rate of shearing

increases. Such changing viscositycoefficients have to be considered in

the pump design for polymer manu-

facturing.

$:+6:

;@

!9 9;

Newtonian fluids

Shear thinning(pseudoplastic) fluids

40

35

30

25

20

15

10

5

0

0 200 400 600 800 1000 1200 1400C+;@ Q (/)

H

,H(4)

1

2

3

4

5

530 mm

505 mm

485 mm

465 mm

440 mm

1

2

3

4

5

W/$ /$! #$/ c$+c! +" a/!a,

/$! AHLSTAR +!a/! c+++* "!!.

Martin Eager / Dreamstime

8/13/2019 STR 2012 2 e Complete

10/32

above 4 %, pumping is very unstable,

and, without special measures, it requires

excessive overdimensioning of the pump.

Sulzer has found a solution to this cus-

tomer requirement by offering degassing

and self-priming units in the AHLSTAR

series, which will stabilize centrifugal-

pump operation with liquids containing

up to 40 % weakly bonded gases or up

to 70 % strongly bonded gases. The

AHLSTAR pumps can be fitted with self-

priming or degassing units to start the

pump with the inlet pipe empty or

to help the pump operate with liquid

containing high gas content, where

conventional centrifugal pumps would

lose suction compatibility.

High efficiency, low energy cost

Energy costs make up about 80 % of the

life cycle cost of a process pump. Sulzer's

engineers have considered this fact when

designing the AHLSTAR pump series.

Traditionally, pumps are operated with

a constant-speed drive motor and a flow

control valve to

adjust the discharge.

This operating mode

can be compared to

always driving a car at full throttle engine

speed and only using the brakes tocontrol the velocity. If the pump motor

is operated using an electronic frequency

converter, it is possible to vary the

rotating speed of the impeller and, thus,

to run the pump at high efficiency in a

broad operating range, making energy

savings of up to 60 % possible. Further-

more, when operated with variable

speed, the pump runs smoothly without

recirculation and with lower vibration

and noise due to the low internal

hydraulic loads. With this smoother oper-

ation, customers benefit from longer

pump life, fewer unexpected shutdowns,

and lower maintenance costs.

Superior reliability

Centrifugal pumps in industrial applica-

tions usually operate over a period of

several decades. The design of the

AHLSTAR pumps 2 aims to minimize

the life cycle costs during the long

expected lifetime. Whereas energy com-

prises the most significant direct cost of

the pump, high reliability and easy main-

tenance help to bring down the indirect

cost. The failure of one pump can stop

the whole chemical processleading to

increased costs and environmental impact

that easily outweigh the lifetime energy

cost of the pump.A design with the goal of achieving

low outage costs for the pump has to

take into consideration two main aspects.

First, a reliable pump design minimizes

the lifetime maintenance costs and

reduces the risk of unscheduled process

interruption. Second, the units must be

designed to be service friendly to shorten

downtime whenever maintenance is

required. One example of this approach

is the innovative impeller mounting,

which allows for easy and quick instal-


POLYMERS

2 Design of the Sulzer AHLSTAR process pump.

What are the challenges of high gas loads?

Gases can be present in liquids in three different states:

Dissolved in the liquid

Bound on the particles contained in the liquid

As free gas in the form of bubblesGas in the form of bubbles disturbs pumping. Gas bubbles

collected in the impeller eye reduce the pump capacity and head.

Pumping becomes very unstable, varies heavily, and requires

excessive overdimensioning of the pump.

Sulzer Pumps has developed pump types, like the AHLSTAR

pumps, which, through their operating principle, remove

disturbing gas or air contained in the liquid so as to maintain

proper pumping. In conventional centrifugal pumps,the free gas accumulates in front ofthe impeller.

AHLSTAR +!a/! 2/$ 1aab! !!

1! a'! !*!#4 a1*# /+ 60% +b!.

8/13/2019 STR 2012 2 e Complete

11/32

lation and dismounting of the impeller.

The highly standardized modular design

of the AHLSTAR range facilitates spare

parts service for the large number of

pumps installed all around the world in

different industrial segments.

Minimal environmental impact

All industries must consider the ecological

consequences of their processes and

reduce the impact of those on the envi-

ronment. The Sulzer process pumps sup-

port these efforts with various features.

Reliable shaft seals

of the pump specif-

ically selected for

pumped liquids and

related applications prevent the pumped

liquids from leaking, and reliable shaft

seals of the bearing unit prevent both

the contaminants from coming into con-

tact with lubricant and lubricants from

leaking. The shaft seals of AHLSTAR

require little or no water lubrication and

thus help to further reduce the environ-

mental impact and operation costs.

Recycled metallic materials, reliable

operation, high energy efficiency, as well

as few leaks from shaft sealing and

bearing additionally minimize the envi-

ronmental impact of the units. Further-

more, over 90 % of the metallic material

used for manufacturing the pump can

be recycled at the end of the pumps life-

time.

Innovative and patented pump design

Pumping critical liquids in demanding

applications requires innovative designs.

Various characteristics of the AHLSTAR

pump range are so advanced that Sulzer

has decided to protect them by patent.

Unusual for a mature product such as

a pump, the AHLSTAR features several

patented designs for hydraulics, shaft

sealing, and bearing unit. These patents

ensure reliable and highly efficient oper-

ation for challenging pumping applica-

tions and help to reduce the number

process shutdowns, limit maintenance

needs, and lower energy consumption,

thereby minimizing total life cycle costs.

The excellent flexibility, durability, and

efficiency make the AHLSTAR pumps aperfect choice for the chemical process

industryand especially for polymer

manufacturing. Several key polymer

producers have turned to Sulzer for the

outstanding pumping performance and

extensive experience.


H M5555Sulzer Pumps Finland OyP.O. Box 6648601 KotkaFinlandPhone +358 500 259 737

[email protected]

POLYMERS

Sulzer Pumps has a full-scale laboratory in Kotka, F inland,and can test the final design options in real operational conditions.

O1! 90% +" /$! !/ac a/!a ! "+

a*"ac/*# /$! ca* b! !c4c!.

8/13/2019 STR 2012 2 e Complete

12/32

Lorenzo Ghelfi:Jolanda is the masterpiece of our

biopolymer team.

4378

You and your team call the new pilot

plant Jolanda. What can Jolanda do?

With this facility, we can produce the

bioplastic polylactic acid (PLA) on an

industrial scale. Jolanda can produce up

to 1000 tons of PLA a year. The starting

materials for our innovative processes

are dimers of lactic acid, which are

extracted from natural raw materials

such as sugar, starch, or cellulose.

What is so innovative about this

process?

Our polymerization process is character-

ized by the unique mixing technology.

With our static mixer technology and

the SMRplus mixing reactor, we can

considerably shorten reaction time and

nevertheless have very good control over

the entire process. Our competitors are

using processes in which the polymer is

retained in large reactors over much

longer time periods. With the increase

in viscosity during the reaction, the dwell

time in such reactors cannot be controlled

across the complete volume of the tank.

Our facility, on the other hand, is

equipped with numerous, very efficient

heating and cooling zones. As a result,

we can precisely control temperature,

viscosity, and pressure at every stage of

the polymerization process, and we can

thereby achieve the desired product

properties.

How did the idea for the new PLA

process arise?

Sulzer has already accumulated more

than twenty years of experience with

lactic acid and derivatives for the pro-

duction of PLA. At the beginning, our

interest was in the preparation and

cleaning of lactic acid products throughrectification. We then developed the

crystallization technique for lactides.

Sulzer Chemtech strengthened its

expertise in the systems area with the

acquisition of the Khni company in

2009. Cooperation with Puracthe

world leader in lactic acid and lactide

productionand Synbra as our end

customer then led to our PLA activities.

We thereby used our well-tested mixing

and reaction technology as the basis, and

we continued to develop the process

specifically for the production of PLA.

A first, continuous pilot plant in

Winterthur with this new PLA tech-

nology delivered such convincing

results that a contract to build a large

installation at Synbra in Holland came

about within a very short time.

With the new process, our customer

can produce bioplastics with higher

quality and tailor-made propertiesand

that at a price that can increasingly

compete with conventional petrochemical

plastics.

The new pilot plant now opens up

entirely new possibilities. What are the

major benefits for the customers?

The new PLA facility in Pfffikon is larger

and more efficient than the existing pilot

system in our test center in Winterthur.We can now also ensure continuous

operation with the operational concept

of the new plant. We employ nine oper-

ators in three shifts in Pfffikon. In addi-

tion, we work closely with our develop-

ment laboratory in Winterthur, where

our analysis team is based.

The new plant has a variety of

functions. It serves as a demonstration

plant for future customers and makes it

possible to train their employees. It is

also used for productionboth for larger


NTERVIEW

The new Sulzer Chemtech pilot plant for bio-

plastics went into operation in Switzerland in

June. In this interview, the Operational Manager

Lorenzo Ghelfi gives us an insight into the

development and importance of this facility.

Lorenzo Ghelfi presents polymer samples from the new pilot p lant.

8/13/2019 STR 2012 2 e Complete

13/32

product samples for customers and for

the development of our own formulations

and new PLA products.

Why do customers want a

demonstration of the technology?

Customers invest millions in large-scale

production plants, and want to take on

as little risk as possible on the technical

side. It is therefore understandable that

the customers would like to see our poly-

merization process one-on-one before

they make their investment. With our

new plant, the customers can precisely

check the energy consumption and effi-

ciency of the process, as well as the

quality of the product, well in advance.

The production of samples is also an

important issue for the customers.

Yes, because the customers carry out

their market development in the time

period from the pur-

chase to the comple-

tion of a PLA plant

and there are many

risks in marketing. Before you produce

the corresponding amounts in the kilo-

ton scale in a large plant, there is always

the question of whether the right

products have been selected, whether

the quality meets the requirements of

specific applications and whether

enough end consumers can be found.

Our customers therefore require PLA

samples to be produced in advance, in

order to be able to manufacture and test

end products such as foils or fibers. With

our facility, we can deliver PLA samples

with various formulations in quantities

from 20 to 200 tons and thereby ensure

that the later production and sale runssmoothly for the customers.

Who are your customers?

We have received inquiries from major

plastics producers as well as many

smaller companies who have cost-effec-

tive access to the natural raw materials.

In many countries in Asia and South

America, plants such as sugar cane or

cassava roots are cultivated in large quan-

tities, so that sugar and starch are easily

accessible. The construction of processing

plants or even complete PLA systems

therein the immediate vicinity of the

cultivation areasis particularly attrac-

tive.

More and more companies around the

world are becoming interested in PLA.

What is the reason for this?

Companies increasingly see a strategic

advantage in producing products from

alternative raw materials instead of min-

eral oil. At the moment, almost all the

products in the plastics market are based

on mineral oil and natural gas. The desire

to become independent of rising prices

and the limited availability of fossil fuels

is a major trend.

Is the PLA business also a growth

market for Sulzer?

Yes, we have ambitious goals. The new

PLA technology and our demonstration

plant should considerably increase our

business with polymers. The currently

still smallproportion of polymer

processing technology in the total sales

of Sulzer Chemtech should increase

significantly in the next few years.

You, yourself, have been with Sulzer

for more than 30 years. What experi-

ence do you bring to this project?

What were the greatest challenges?

I bring experience in engineering and

management. Managing a purely chem-

ical production is a new challenge for

me. But thanks to my life and professional

experience, I can comfortably deal withunexpected situations.

It has been particularly challenging

to coordinate the teams from three

locations and to thereby keep to time

and cost schedules. Our colleagues in

Allschwil built the plant. The depart-

ment in Winterthur is responsible for the

engineering, while we in Pfffikon carry

out the assembly. Thanks to the great

dedication of all our employees, we have

been able to overcome all these difficul-

ties.

How would you differentiate this

project from the earlier ones that you

carried out for Sulzer all over the world?

I have worked for Sulzer all around the

globe: in Brazil, Argentina, Russia, and

the USA. This time, in the new project

in Switzerland, there are no difficulties

with regard to cultural and language

differences. However, the official regula-

tions and specifications for work and

environmental protection are dealt with

much more strictly here.

Why has Sulzer Chemtech decided on

the location in Pfffikon? Can produc-

tion be cost effective in the high-wage

country of Switzerland?

Customers from all over the world visit

us and appreciate the proximity to the

sales department of Sulzer Chemtech as

well as the easy accessibility via the

nearby Zurich International Airport.

Switzerland offers an ideal environment

for high-tech industry. Furthermore, we

also benefit from the proximity to our

development department, which supports

us in the operation and optimization of

the plant. This would not be possible at

other locations. And, as we work effi-

ciently following LEAN principles, we

are also competitive at the location

Switzerland.

What is planned for the future?

We are planning to operate Jolanda for

some years in order to establish the new

PLA technology on the market. The sig-

nificant investment in this polymer

system should act as a trigger and lead

to the breakthrough of the technology.

Interview: Tnde Kirstein


INTERVIEW

L6956 Gstudied mechanical engineering at the ZHAW (ZurichUniversity of Applied Sciences), Winterthur, Switzerland.He worked as a project engineer in the field of industrialcombustion technology for metallurgy and power plantconstruction. He has been working for Sulzer Chemtechfor more than 30 years in the fields of internationalsales, project management, and engineering, as wellas the production of process equipment for theinternational construction of chemical plants and oilrefineries. During his foreign deployments in managingpositions in Argentina, Brazil, Russia, and in the USA,he built up new business units for Sulzer and expandedthe global market p resence of Sulzer Chemtech.He recently returned to Switzerland following hisdeployment of several years in Russia and is nowmanaging the buildup and the operation of the polymer

pilot plant in Pfffikon.

W/$ J+a*a 2! 2a*/ /+ !/ab$ + *!2 PLA

/!c$*++#4 +* /$! a'!/.

8/13/2019 STR 2012 2 e Complete

14/32

The use of surface coatings or treat-

ments has gained acceptance as a

way to improve tools in the produc-

tion of plastics. Depending on the appli-

cation, different thin-film technologies

are used for wear and corrosion

protection and for the minimization of

friction.

Sulzer Metco is a market leader for

coating services, and it works together

with well-known customers in the

plastics industry. For example, the Coca-

Cola Company in China produces all its

caps with tools that have been coated

by Sulzer Metco. More than 25 % of all

beverage caps in the world are produced

with tools that have been coated by

Sulzer Metco 1. Surface solutions from

Sulzer Metco not only fulfill the high

requirements of the food industry, they

are also used in the demanding pro-

duction of medical engineering products.

Tools that have been coated by Sulzer

Metco produce around 15% of all medic-

inal disposable syringes worldwide.

Wide range of stresses

The surfaces of plastic molds or tools

are subject to many different stresses in

the production process. The major wear

mechanisms in the production of plastics

are:

Corrosion, above all, in the form of

surface and pitting corrosion

Fouling by the smallest particles or

coatings on the tools

Abrasive wear as a result of particles

embedded in the plastic

Cavitation (tool-damaging bubbles

in the plastic material) through local

vapor pressure differences in the

flowing medium

Adhesive interactions

Surface damage when cleaning

the tools

Additives enhance the wear mechanisms.

The additives that are important for plas-

tics can be dyes, plasticizers, or other

More effective manufacturingthrough coated tools

Beverage caps and disposable medical syringes have something in common:

They are produced with tools whose modified surfaces are particularly resistant.

Sulzer Metco has many years of experience in the development of tailor-made

surface coatings and treatments for every kind of loading.

More than 25% of all beverage caps worldwide, including those for Coca-Cola in China, are produced usingtools that have been coated by Sulzer Metco.

Efficient processing of plastics


POLYMERS

4379

Liz Van Steenburgh / Dreamstime

8/13/2019 STR 2012 2 e Complete

15/32

fillings, such as glass fibers or chalk.

They are used to influence component

properties such as strength, elasticity, and

hardness. At the same time, however,

these modified plastics place more load

on the tools during the production

process and increase wear.

A coating or heat treatment of the tools

can reduce the abovementioned wear,

which increases their service life and

reduces the maintenance outlay. At the

same time, a modified tool surface can

significantly reduce production costs by

saving on separators or lubricants.

The right solution for every demand

The thin-film technology division of

Sulzer Metco offers individual solutions

for many different requirements. These

include plasma heat treatments and coat-

ings as well as a combination of the two.

The selection of the appropriate surfacetreatment depends on the plastics and

elastomers to be processed and the

specific parameters of the production

processes.

Improving the surface with heat

Surfaces can be improved with thermo-

chemical heat treatment. The thin-film

division of Sulzer Metco offers its cus-

tomers two process variants of heat treat-

ment:

The patented IONIT OX procedure

gives treated materials excellent

resistance to corrosion and wear, and it

has proven to be an environmentally

friendly alternative to hard-chrome

plating. It is frequently usedeven in

the sensitive food industryand is a

combination of gas nitrocarburization,

plasma-nitrocarburization, and subse-

quent oxidation.

Resistance to wear and friction and

sliding properties can be improved

with the IONIT procedure, which

can also be used for high-alloy steels,

super alloys, and light metals such as

titanium and titanium alloys.

Cost savings are possible in both proce-

dures, above all, through the replacement

of expensive materials. For example, tem-

pered steels, which are considerably

cheaper, can be used in place of stainless

steels.

Proven coatings for the plastics

industry

In coating processes, a distinction is made

between physical vapor deposition

(PVD) and chemical vapor deposition

(CVD). Coatings with thicknesses in the

micrometer range are applied in both

procedures.

The following PVD hard coatings have

proved effective in the area of the plastic

and elastomer processing industry:

Titanium nitride (TiN)

Aluminum titanium nitride (AlTiN)

Chrome nitride (CrN)

Multilayer chrome nitride

Modified chrome nitride layer

(CrNmod) 2.


POLYMERS

Types of heat treatments

The generic term nitriding stands for processes in which the edge regions of ferrous

materials are enriched with nitrogen. If carbon is also supplied at the same time, this

is referred to as nitrocarburation. This process improves the resistance to wear, the

hardness, and the friction and sliding properties of the material. Two subcategories

are differentiated in nitriding:

G 5;96+9*

8/13/2019 STR 2012 2 e Complete

16/32

PVD and CVD are well-proven coating processes:

In @+ =69 6;65 (PVD), the initial material is

transferred into the gas phase with physical processes and

is condensed onto the component to be coated. Commonly

used variants are vacuum arc evaporation and magnetron

sputtering.

In +4+ =69 6;65 (CVD), material is deposited

onto a component from the gas phase by means of achemical reaction.


POLYMERS

What is PVD and CVD?

Thermoplastic synthetics, such as

polyetheretherketone (PEEK), and elas-

tomers, such as natural rubber, can be

successfully processed. PVD coatings are

also successfully used in the extrusion

of polyethylene (PE) or polypropylene

(PP), among other applications, as well

as on polyethylene terephthalate (PET)

molding tools.

Customer successes demonstrate the

advantages

PVD coatings contribute significantly to

increasing performance and productivity:

In the case of coil distributors coated

with CrNmod for the production of

films from polyvinylchloride (PVC) or

polypropylene (PP), customers have

reported increases in service life of a

factor of 10. The sliding properties of

wide-slit nozzles coated in this way were

also improved by 30 %3

.

Versatile use of carbon coatings

Diamond-like carbon (DLC) coatings

can be applied using the PVD process

or the PACVD (plasma-assisted chemical

vapor deposition) process. The PACVD

process is a plasma-assisted variant of

the CVD process, in which temperatures

are considerably lower and do not

exceed 200 C.

DLC coatings of the type a-C:H (hydro-

gen-bearing amorphous carbon coatings)

are used above all in the plastics industry.

The particularly smooth, amorphous

a-C:H coatings are utilized for optically

high-quality surfaces, for example, in

CD and DVD production.

DLC coatings are also used with great

success on tools in the cosmetics industry4, as well as for ejector pins, cores, and

sliders in injection molding. The benefits

are:

Reduction of scale formation

Excellent wear and corrosion protection,

even at the standard film thickness of

24 microns

2 CrNmod-coated molds are used in the automobile industry.

Prevention of slip-stick effects (these

arise from a reduced difference

between sliding and adhesion friction)

Elimination of burner streaking

Improvement of the flow behavior

of the polymer melt and, thereby, an

increase in the transport capacity

Customers benefit from DLC coatings

Customer examples show how effective

the coating of tools can be: cores for the

manufacture of disposable syringes have

to be cleaned every three to four hours

if uncoated. After a DYLYN/DLC coat-

ing, no cleaning was necessary, even after

one and a half years. Corrosion problems

were also eliminated.

Similar benefits were also seen in

textured blow molds coated with

DYLYN/DLC: instead of regular

reworking in a two-week cycle, produc-

tion without rework could be continued,

even after eight weeks.

Pioneering Psolid diffusion coating

for high-gloss mirror surfaces

The new Psolid diffusion layer represents

one of the most innovative approaches

to tool surfaces in plastic injection

Vacuum pump

Substrate

Gas supply, e.g. CH4

Reactive plasma

Plasma generator

C$D 96+

In the thermal CVD process energy issupplied in form of heat; in the plasma-assisted CVD process, (see figure) agas is excited in a plasma.

1

2

3

4

5

Vacuum measurement andcontrol system

Circular evaporators

Power supplies

Coating chamber

Process gas

Vacuum pump set

Window

Infrared temperaturemeasurement

Substrate holder

BIAS power supply (substrate)

P$D 96+

1

2

3

4

5

6

7

8

9

10

PVD c+a/*# *c!a! /$!

+c/1/4 #*"ca*/4.

5 6

1

2

3

4

5

2

1

3

4

7

8

10

9

8/13/2019 STR 2012 2 e Complete

17/32

molding and extrusion molding. Using

this method, a scratch-free passive layer

that has a high resistance to corrosion

and pitting is formed on the surface of

the tools and molds.

The use of a Psolid

coating on corrosion-

resistant steels or

cold-working steels with high chromium

content provides hardening without any

loss in corrosion protection. In the

coating of hot- and cold-working steels

in particular, the diffusion layer creates

tool surfaces with values up to 1600 HV.

With a diffusion depth of 1050 m,

coated components nevertheless remain

constant in size and shape.

Time savings in the production of

high-gloss surfaces

Due to the large outlay in time and the

enormous cost factors when machininghigh-gloss or polished mold surfaces,

savings are urgently sought in the

plastics processing industry. A time

saving for converting a polished surface

to a high-gloss surface is possible thanks

to Psolid. The wear-resistant coating pro-

tects against adhesion, considerably

reduces deposits, and facilitates mold

cleaning. Visible defects in the plastic

parts can be excluded, as the layer neither

flakes nor becomes brittle.

Users in the plastics-processing in-

dustry, polishing companies, and tool

manufacturers profit from the consider-

able advantages of a Psolid coating 5.

The time savings reduce production and

repair costs dramatically, while simulta-

neously providing a considerable

improvement in the uptime of the tools.

Advantages of combined treatment

The combination of plasma nitration

with subsequent coating using PVD or

PACVD combines the advantages of both

types of surface treatment. Steels that

contain proportions of special alloying

elements (chrome, aluminum, vanadium,

molybdenum) can achieve high surface

hardness and represent an excellent basis

for the subsequent coating. The mechan-

ical properties of the material core, such


POLYMERS

3 Nitrided wide-slot nozzles are coated inthe Sulzer installation.

4 DLC-coated components are used in the manufacture of cosmetic pencils.

W/$ P+ c+a/*# /$! a/c +c!*#

*/4 +"/ "+ c+*!ab! /! a1*#.

5 Matrix blocks for the manufacture of disposable syringes havecavitation holes on the inside. These cannot be coated with traditionalcoatingswith P.+(%, it is unproblematic.

8/13/2019 STR 2012 2 e Complete

18/32

as toughness and crack resistance, remain

unchanged.

With the combined treatment, the load-

bearing capacity of the surface is deci-

sively improved, so that the infamous

eggshell effect does not occur (see

infobox).

In the processing of glass-fiber-rein-

forced polymer materials, these kinds of

hardened tool surfaces prevent the added

hard additives from being pressed into

the tool surface at high process pressures.

In plastics processing, the tools have

to be cleaned at the latest during a pro-

duction change. Polymer residues are

thereby usually removed using scrapers

and spatulas made from steel, which

can easily lead to damage to the surface.

This damage can be avoided through

the supportive effect of nitriding.

Sulzer Metcoa strong partner for

coating solutions

In the field of thin-film technology, Sulzer

Metco has service centers worldwide for

the contract treatment of tools and com-

ponents. In addition to services for

surface improve-

ment for various

industrial and appli-

cation areas, its own

system construction division delivers

innovative new developments and

further developments through its own

research and development work. The

service teams have many years of expe-

rience in dealing with plastic tools. The

members of staff make use of their exten-

sive experience in the industry to provide

the clients with targeted consultation.

A special feature is the contract treat-

ment of long and large parts. The max-

imum dimensions for large-volume parts

are: 1800mm long, 1500mm diameter,

and 3.18m3 total volume. Furthermore,

extruder screws or wide-slot nozzles up

to lengths of 4500mm, diameters up to

600mm, and volumes of 1.27 m3 can be

treated 6.


POLYMERS

"64

8/13/2019 STR 2012 2 e Complete

19/32

The most highly developed examplesof the natural silk technique are thewebs of cross spiders and other orb-

weaving spiders. They construct a

vertical, two-dimensional web between

two anchor points that are relatively far

apart. Starting from a first, bridging

can thereby cushion the impact of the

collision. If the stretched thread were to

then spring back to its original position

like a rubber rope, the insect would be

catapulted back into freedom as if from

a trampoline. But because the web

returns only gently after the rapid expan-

sion, the prey remains caught. The trick

lies in the sticky water drops. The silk

thread is rolled up on the drops through

the surface tension of the liquid. The

resulting numerous loops cause, like a

cable reel, both the rapid extension and

the braked rerolling of the thread.

A targeted mix of amino acids

The silk technique of the cross spider is

also amazing because, in its abdomen,

the animal carries a selection of seven

different silk glands, which lead into a

complete battery of spinnerets. Depending

on the function of the thread, it is

produced with a special mixture of amino

acids for a specific thickness and

elasticity. For example, there are different

silk materials for the frame and the

spokes, for the auxiliary spiral, the catch-

ing spiral, or the glue for linking and

attaching the threads.

The thread itself also has a sophisticated

design. Although still a liquid made upof keratin molecules in the silk glands,

the protein mass transforms itself within

milliseconds when squeezed through the

narrow valve of the silk gland. Strong

shear forces compel the keratin to take

on a specific structure: A part of the

protein folds like the bellows of an accor-

dion to form solid crystals, while the

rest encases the crystals as disordered

molecule chains, like a ball of spaghetti.

A thread that is both elastic and extremely

tough results from this procedure. The

tensile strength of spider silk is around

2500kg/cm2. Relative to its weight, it is,

therefore, five times stronger than steel.

Medical and musical applications

In order to be able to make use of spider

silk technology, the genes involved have

been isolated recently and have been

introduced into bacteria for silk produc-

tion. Possible product applications are

artificial tendons and ligaments, bandages,

or fabrics for bulletproof vests. There is

a great deal of interest now in the devel-

opment being done by the Japanese pro-

fessor for polymer chemistry Shigeyoshi

Osaki. Thousands of threads from the

spider species Nephila maculata have

been woven into compact strands that

can now be used as violin strings. After

the first trials, violinists highly praised

the soft and full tones of the silk strings.

With their silk glands, spiders produce a silk material withexceptional properties.

thread, the spider constructs the basic

framework of the orb web with edge

threads and spokes and, finally, the catch-

ing spiral by means of an auxiliary spiral.

Any insect that hits the web will become

caught on this catching spiral through achain of extremely sticky pearl-like drops

made up of water and glycol proteins.

Gently catching a bomber

The web that catches the insects has to

cope with an enormously challenging

task. If, for example, a large fly hits one

of the one-thousandth-of-a-millimeter-

thick threads, it is like a bomber, and

the impact should actually break the web.

However, the silk threads can stretch to

up to five times their original length and

4375

Spider silk as a superpolymerMacromolecules are formed by the polymerization of base molecules and

form the basis of life. For example, proteins consist of thousands of amino

acids, and nucleic acids build up the genetic code from millions of nucleotides.

Spiders have an amazing technique for building complex spatial structuresfrom protein chains.


SULZER ANALOGY

Spider silk is a wonder of nature and can even

improve the sound of violins.

H9*9; C9

8/13/2019 STR 2012 2 e Complete

20/324380

Sulzer Innotec supports the Sulzer

divisions and external clients in

polymer analyses with its modern

laboratory and its many years of

expertise in plastics. The following

project examples from Sulzer Innotec

show that many factors (such as material

composition, component manufacturing,

and operating conditions) have to be

taken into account in polymer analysis

in order to uncover the causes of short-

comings and to find adequate solutions

for them.

Case 1: What kind of constituents are

in the plastic?

As a result of globalization, polymer

materials and, in particular, high-perfor-

mance plastics that supposedly have

the same composition are available from

various manufacturers. The price of

the material plays a central role in the

choice of the supplier. The selection is

still not easy, however, because the

quality differences are often not recog-

nizable at first glance. In order to ensure

that the component quality remains

the same, even following a change of

supplier, it is recommended that buyers

carry out a detailed analysis of the

Following the trail of polymeric evidencePlastics are being used more and more frequently in modern machinery and equipment

design because they are light, resistant to corrosion, and cost effective. In order to

obtain optimal plastic properties, technological analyses are essential. Due to the many

influencing factors and complex issues, however, the interpretation of results requires

extensive knowledge and, in many cases, detective-like instincts.

Micrographs clearly illustrate how plastics are composed of different constituents(thin section under polarized light).

Polymer analysisbetween measurement and interpretation


POLYMERS

8/13/2019 STR 2012 2 e Complete

21/32

replacement material in advance.

Deficiencies occurring in operation

can thereby be avoided from the very

start.

Comparing suppliers

For an external client, Sulzer Innotec

compared carbon-fiber-reinforced modi-

fied PEEK materials from two different

suppliers. For the end product, which

is subjected to high mechanical and

tribological loads, the client wanted to

replace the feedstock pellets from

supplier A with the cheaper pellets from

supplier B. Sulzer Innotec was asked

to determine whether or not the main

components of the two materials were

qualitatively and quantitatively the same.

To start with, standard laboratory test

methods were applied to the problem:

Fourier transform infrared spectro-

metry (FTIR)

Thermoanalysis:

Differential scanning calorimetry

(DSC)

Thermogravimetric analysis (TGA)

Dynamic mechanical analysis (DMA)

Optical microscopy

The results of the FTIR analyses

showed an optimal match with the data-

base spectrum of PEEK for both feedstock

pellets A and B. No indication of the

supposed PTFE lubricant (Teflon) was

found in either feedstock by means of

FTIR. The results of the thermoanalytical

investigations also revealed no obvious

differences between the pellets from the

two suppliers. The two temperature

peaks at approx. 21C and 330 C for

the two materials clearly indicated the

presence of PTFE, however. With addi-

tional investigations (thermogravimetry

and optical microscopy), the relative pro-

portions of PEEK,

PTFE, carbon fiber,

and graphite could

be determined. The

comparison between

the two feedstocks also showed no

differences here.

The same, but not the same

According to the analyses, the pellets

from the two suppliers should have been

able to be processed into end products

with equivalent properties. However,

although the qualitative and quantitative

composition of the two materials was

shown to be the same and although the

fabrication of the end products was

carried out using the same processing

parameters, the resulting products made

using feedstock B exhibited suboptimal

properties: These parts exhibited sliding

behavior deemed insufficient for the

intended application.

The material analysts from Sulzer

Innotec were able to discover the cause

of this discrepancy. Thanks to scanning

electron microscopy (SEM) of the two


POLYMERS

1 Only in the scanning electron micrographs can a difference be seen between the pellets: The PTFE filler(light color) in material A (left) has a different distribution from that in material B (right).

Plasticsa mix of individual components

As a rule, polymer materials are available in the form of feed-

stock pellets, which are processed further using extrusion or

injection-molding processes. Polymeric base materials in-

clude, for example, polyethylene (PE), polyamide (PA), and

polyetheretherketone (PEEK). In order to meet the detailed

performance requirements for the finished parts, various ad-ditives are mixed together with the base material in a com-

pounding process.

The finished feedstock is therefore the mix of:

The base polymer

Processing aids

Reinforcing agents

Aging and flame retardants

Dyes and other materials

The composition of the feedstock material is part of the

know-how of the respective material manufacturer and is a

closely guarded secret due to the development work that

went into it.

10m10m

D!/! ab#+ /!/ !/, S5! 2a

ab! /+ /ac! /$! ca! +" /$! *""c!*/

a/!a b!$a1+.

8/13/2019 STR 2012 2 e Complete

22/32

A change in the processing parameters has many consequences

As the market for the plastics-processing industry is very competitive, many

manufactures try to save costs in the processing of polymer materials. As a result

of variations in the processing parameters (pressure, temperature, speed), it is

possible to make plastic components with very different properties from the same

materials on the same production line.

However, changes in the processing parameters and/or reductions in the cycletimes can affect the quality of the end products. It is not uncommon for problems

to arise with plastic parts that are subjected to high stress. This can have conse-

quences for the part, particularly during long-term operation.

pellet types, they were able to detect sig-

nificant microscale differences between

the two materials. While in feedstock A,

the PTFE phase (light-colored in Fig.1)

was relatively evenly distributed and

took on a spherical form, in feedstock B,

the PTFE component appeared as locally

concentrated agglomerates looking some-

thing like popcorn.

The difference concerning the appear-

ance of the PTFE can be traced back to

the use of different types of PTFE in the

two feedstocks. With this knowledge, the

poorer sliding properties could be con-

clusively explained, and consequently

the client decided against a change of

supplier.

Case 2: How is the plastic processed?

A change in the process parameters can

save manufacturing costs, but can also

negatively affect the component quality.

In order to detect deficiencies in quality,

material analysts use test methods that

react sensitively to changes in the pro-

cessing parameters. Using modern sim-

ulation programs programs to model the

filling behavior or temperature and stress

distributions, the manufacture of plastic

components can be visualized and the

processing can be effectively optimized.

With some components, such as trans-

parent plastics, it is easy to reveal unfa-

vorable processing parameters 2. It is

more difficult to analyze the processing

parameters of long-life components of

high-performance plastics, as the follow-

ing case shows.

A smaller temperature peak provides

the first clue

Sulzer Innotec investigated two oil

scraper rings that behaved completely

differently under the same operating con-

ditions3

. While one worked flawlessly,massive breakout was found on the

scraper edges of the other after only a

short operating time. The measurement

results for both components yielded

almost identical melting curves. Only a

small peak between 200 C and 230C,

which occurred at a higher temperature

in the thermogram of the defective com-

ponent, indicated a small difference

between the thermoanalytical results of

the analyses of the two components. For

the materials analyst, this inconspicuous


POLYMERS

2 The images of the polystyrene lid taken under polarized light reveal residual stressesin the material, which stem from the manufacturing process.

Injection point

Discoloration resultingfrom residual stress.

20mm

free of damage

defective

3 Two identically manufactured oil scrapers made of PPS behave completely differently in operation.

M+!* a/+* +#a

$! /+ +/5! /$! a*-

"ac/! +" a/c.

8/13/2019 STR 2012 2 e Complete

23/32

difference was a first clue answering the

question as to whether the breakout was

due to the composition of the material,

the processing, or the operating condi-

tions.

Inadequate predrying led to brittleness

In the case of the scraper, the detected

anomaly could be definitively assigned

to the processing procedure. Further

investigations showed that the starting

material of the brittle scraper did, indeed,

have the same composition, but that the

material had been insufficiently predried

before it was processed. Due to the

residual moisture that was present, the

manufacturer had to change the pro-

cessing parameters in order to produce

scrapers that were optically perfect. This

change resulted in the detected, higher

peak temperature of the brittle, failed

scraper. As this example shows, the pro-

cessing of the components must also be

taken into account when explaining defi-

ciencies in end products.

Case 3: What happens to the plasticin the operation?

The analysis of damage caused in oper-

ation is challenging because of the many

influencing factors which need to be con-

sidered. Seals and O-rings in heavy-duty

applications represent typical examples

of this kind of question. Component per-

formance is not only a question of the

seal geometry and the temperature-

dependent mechanical properties of the

material, but also of the thermochemical

processes that occur in operation. A quick

on-site assessment of the situation is dif-

ficult, because the causal factors influence

each other and are not obvious.

Sulzer Innotec investigated defects in

the seals of water-cooled engines, for

which silicone O-rings were used.

According to the

data sheet from the

material manufactur-

er, the silicone used

is resistant to water

and steam at operating temperatures

below 130C. However, leaks in the seals

were detected after an operational period

of only six months 4.

Specialists from Sulzer Innotec

assessed the seal geometry and the

O-ring groove on site and found

them to be in order, but detected massive

damage to the O-rings themselves 5.

The deformation of the O-rings and

the numerous cracks along the entire

circumference indicated the occurrence

of a thermal degradation process. Labo-

ratory tests on unused O-rings were able


POLYMERS

4 First on-site inspections provide only few indications of the causes of defects(e.g., at these O-ring seals in a water-cooled engine).

Analysis of damage caused in operation

A number of factors can lead to the failure of plastic parts in operation:

Mechanical stresses (time- and temperature-dependent creep and relaxation

processes)

Thermal stresses

Chemical stressesAs these three factors are interdependent, it is not enough to assess their

operational impact individually. The analysis is made more difficult by the complex

and secret compositions of the plastic compounds. In particular when installing off-

the-shelf plastic components, it is not possible to judge whether or not both the

material and the processing were correct. It is therefore challenging to interpret the

analysis results correctly and to attribute them to the operating conditions where

necessary.

I* ca! +" aa#! ca! * +!a/+*, S5!

a*a45! *+/ +*4 #!+!/ca a* !c$a*ca

+!/!, b/ a+ /$!+c$!ca +c!!.

8/13/2019 STR 2012 2 e Complete

24/32

to show that both material and manu-

facturing quality could be excluded as

causes of the failure.

Moisture and heat decompose the

plastic

More-detailed analyses finally led the

analysts at Sulzer Innotec onto the right

track: The damage

to the O-rings was

due to a chemical

decomposition of the

silicone as a result of the conditions expe-

rienced in operation. The cause was a

damp environment (hydrolysis) at a tem-

perature that was too high (significantly

above 130 C). Consequently, the macro-

molecules of the O-ring material were

being split chemically, resulting in short-

ened molecular chains and the consequent

embrittlement of the material. The degen-

eration process could be reproduced in

laboratory trials, since degradation also

occured without the mechanical loading

typically experienced in operation 6.

The client had two options available

based on this result: Either reduce

the operating temperature in the area

of the O-rings to below 130 C, or replace

the silicone with a more suitable

elastomer material. Using aging trials

developed and performed out in-house,

Sulzer Innotec was able to narrow

down the choices and recommend the

best-possible sealing material 7. Follow-

up checks on the seals in use confirmed

the good results from the laboratory.

Based on the results from Sulzer Innotec,

a major material change to a special

fluoroelastomer was initiated.

It is the right interpretation

that matters

As the above examples show, it is not

simply performing the measurements

themselves that is difficult in plastics

analyses; the interpretation of the meas-

urements requires almost detective-like

instincts. It is particularly challenging

when it is not possible to precisely

analyze all the required parameters.

In order to be able to draw the right

conclusions in complex issues, inter-

disciplinary expertise in the area of

plastics technology, in addition to

close and open-minded cooperation

with the client and extensive experience

in polymer analysis, is decisive for

success.

G5;9 D959Sulzer InnotecSulzer-Allee 258404 WinterthurSwitzerlandPhone +41 52 262 69 41

[email protected]


POLYMERS

10mm

7 Aging trials for the selection of a suitable sealing materialwere carried out in the laboratory.

Ba! +* S5!7 /!/ !/, a a&+ a/!a

c$a*#! 2a */a/!.

FPM Special EPDM Silicone Silicone Viton

!

8/13/2019 STR 2012 2 e Complete

25/32

Sulzer Metco has a modern and growing

location for diamond-like carbon coatings

(DLC) in Limoges, France. These coatings

are particularly suited for use in automotive

applications and motor sports.


SULZER WORLD

4381

The location in Limoges isworld-famous in motor sports for

diamond-like carbon coatings.

T

hrough the acquisition of Bekaerts

DLC division in 2010, Sulzer Metco

expanded its technology portfolio in the

area of thin-film surface coating. The

location in Limoges that is involved in

this field has a long history of success

with DLC coatings. The first engines

were coated with DLC here as long ago

as 1995, and the location has experienced

active growth in the meantime. This is

especially evident from the numerous

expansion activities in the production

halls in the last few years. Clients can

be sure that the 65 employees at the loca-

tion will guarantee the very best quality

at all times.

Established in motor sport

growing in new markets

DLC coatings such as CAVIDUR and

DYLYN are characterized by their espe-

cially smooth textures. At the same time,

they display low coefficients of friction

and a very high resistance to wear. It is

for exactly this reason that they are par-

ticularly suitable for use in motor sport,

where every millisecond is crucial.

Formula 1 teams worldwide are equipped

with DLC coatings. At the Limoges site,

the majority of the business is generated

in motor sport. Significant and steady

growth can, however, also be seen in the

fields of plastics, automobiles, engineer-

ing, and metalworking. Surface solutions

for the semiconductor industry are also

being offered in increasing numbers.

The highest standards for

equipment and control

Limoges has a modern, fully automated

cleaning line that meets all customer

requirements. Eleven coating installations

are currently in continuous operation.

These include DLC coating installations

and a PVD (physical vapor deposition)

system. In particular, Limoges is able to

guarantee a high quality of production

through its cleanroom. A special feature

of the Limoges site is the final inspection

at the end of the coating process: visual

inspections as well as additional mechan-ical and computer-supported analyses

in some cases with equipment developed

inhouse for large componentsensure

the highest quality of the end products.

Center of excellence and coopera-

tion with universities

In order to be able to guarantee state-

of-the-art coating solutions for clients,

the site also operates an R&D system.

Coatings that have been modified

and further developed can be tested

under realistic production conditions,

which makes the rapid transition to a

sustainable production process particu-

larly easy.

In addition, Limoges is currently

working together with the University of

Limoges and leading partners from the

automobile industry on a research project

that will set new standards with its

DYLYN coatings. The proximity of the

location to the university, which is only

500 meters away, facilitates the continuous

cooperation with qualified students and

institutes.Sulzer Metco in Limoges stands out

through its impressive diversity. In addi-

tion to modern coating installations and

high-tech equipment, the expert knowl-

edge of the employees is just as important

as the wide competence network with

industry and research. Through the expe-

rience and the broad-based expertise of

the employees in Limoges, Sulzer can

continue to grow internationally and

expand its position as a technology

expert.

Welcome to Sulzer Metcoin Limoges

T$! /!a * L+#! !/

*!2 /a*a 2/$ / DYLYN6

c+a/*#.

8/13/2019 STR 2012 2 e Complete

26/324382

Finding defects in turbine blades is

one important task of the lock-in

thermography setup at Sulzer Turbo

Services 1. An ultrasound transducer

introduces elastic waves (propagating

elastic deformations) into the turbine

component. In homogeneous material,

the reflected waves are evenly distributed.

However, at locations where the alloy is

damaged, some of the wave energy is

absorbed, and heat is generated. This

heat has a different infrared (IR) radiation

than its surrounding area and is detected

by the IR camera 2 (see infobox).

Infrared images reveal defects

Modulation of the ultrasonic wave

improves the heat contrast and provides

an amplitude image and a phase image

of the turbine component. The amplitude

image is a measure for the temperature

and is related to the thermal diffusivity.

The phase image reveals the size and

depth of the defect. The phase is a result

of a shift in the output signal with respect

to the input signal and is related to the

propagation time or depth.

Insightful hot spotsLock-in thermography is a versatile inspection method capable of identifying

defects in gas turbine parts. Sulzer Turbo Services Venlo uses this advanced

method not only to examine turbine components, but also as an R&D instrument

to improve turbine design and repair to the benefit of the customers.

1 Sulzer Turbo Services Venlo uses ultrasonic thermography for turbine inspection and research.

Thermographic inspection of industrial gas turbine components


PANORAMA

1

2

3

1 2

3

IR camera

Turbine part

Ultrasonic transducer

8/13/2019 STR 2012 2 e Complete

27/32Sulzer Technical Review |2/2012 27

PANORAMA

3 The results of a thermography inspection show damage to a turbine blade.The magnified image on the top shows an internal crack; the magnified imageon the bottom shows a crack on the surface.

Thermographic inspection

In thermographic inspection, an infrared

(IR) camera measures and visualizes the

heat distribution within an object.

There are two approaches:

In = ;9469@, the exist-

ing thermal radiation of an object is

measured. Common applications are

the detection of insulation faults inhousing, detection of overheating in

power supply stations, and level

detection in storage tanks.

A+;= ;9469@ introduces

energy into the object and measures

the objects response. One method

is lock-in thermography, which uses a

transducer to introduce ultrasonic

waves into the object.

2 The detectionprinciple of lock-in thermographyis based onultrasonic wavesthat generateheat at damagedlocations insidethe turbine part.

The bright spots in the phase image

need to be inspected in more detail in

order to determine whether the hot spot

is a real defect. For this reason, the

sequence profilewhich is the amount

of radiation measured on one spot in

timeis analyzed. The sequence

profile of a defect is different from the

profile of other surrounding heat sources,

for example, the reflection of a lamp.

A defect shows a response curve similar

to the modulation frequency of the

excitation.

Distinguishing between internal and

external defects

Sulzer Turbo Services Venlo applies lock-

in thermography to identify structural

defects in turbine parts. Such defects

include cracks along the grain boundary

that have been caused by corrosion, oxi-

dation, mechanical stresses, or casting

defects.

Because turbine parts are made of

metal alloys, the heat signature generated

is not just limited to the defect itself. Theheat is conducted and creates a slightly

weaker hot spot that is larger than the

defect itself. The advantage of this

thermal conduction is that the heat sig-

nature of internal defects is detectable

as a diffuse heat source at the surface.

Thus, ultrasonic lock-in thermography

can detect both external as well as

internal defects. Figure 3 shows the

detection of cracks on the surface and

inside of a blade. This method has

significant advantages over other

approaches. For instance, fluorescent

penetrant inspection cannot detect inter-

nal defects and borescopic inspection is

time consuming.

Evaluating coatings with thermography

Ultrasonic lock-in thermography can

also detect a lack of proper bonding

between the parts and their metallic coat-

ing. The elastic waves cause vibration in

the part. If the coating is bonded properly

to the base material, no friction heat is

observable. Friction between the part and

the poorly bonded coating creates a

bright thermal signature. Recently, ther-

mographic inspection has been compared

with conventional manual ultrasonic

inspection with a probe, and a 100 %

match of observed indications has been

achieved.

FFT

IR camera

Turbine blade with defect

Phase image

Amplitude image

Elastic wave

Thermal wave

Ultrasonic excitation Lock-in frequency

8/13/2019 STR 2012 2 e Complete

28/32

Detection of blocked cooling channels

For turbine components, cooling is very

important to extend and protect compo-

nent life 4. During the repair of vanes

or blades with cooling channels, it must

be ensured that all cooling holes are open.

An IR camera can show at a glance

whether cooling

holes are blocked

or open. This is

achieved by blowing

warm air through the component. A ther-

mal image of the part is recorded in

order to visualize the heating of the com-

ponent. Figure 5 shows an example of

such a recording. Open cooling holes

appear in bright yellow because of the

heating by the warm air. Blocked cooling

channels are not heated; they appear as

a blue-black color.

Research on the efficiency of cooling

holes

Sulzer has started a research project in

order to develop a method of evaluating

the efficiency of cooling channels of tur-

bine blades and vanes. The results of

this project will provide more information

about how the cooling-hole geometry

affects the cooling efficiency.

The research is based on a heat transfer

model that has been developed by the

str 2012 2 e complete

Documents