metal cutting methods - didaktdidakt.no/stat/pm/plasma_oxy_waterjet_comparison.pdf · 2015. 2....

Comparative

Cutting

Comparing the four major

plate and sheet cutting

processes.

Copyright, 2003 Hypertherm, Inc.

These materials cannot be reproduced in any form

without the permission of Hypertherm, Inc.

Jim Colt Dave Dumas

- CNC Plasma Cutting - CNC Laser Cutting - CNC Oxy-Fuel Cutting - CNC Abrasive Water Jet Cutting




Plasma will cut all electrically conductive metals. The major strength is with carbon steels in the range of gauge to 2” thickness using

a high definition oxygen based plasma system. Good quality on stainless and aluminum in the range from gauge to over 1” can be

achieved, with maximum piercing on stainless and aluminum to 4” thick, and edge start cutting to 6-1/4” There are a variety of

different plasma processes using different gases, power levels and levels of arc constriction….these process variations will provide

different edge metallurgical effects based on the heat affected zone and chemical effects.

Laser cutting technologies are available with a wide array of power ranges. The most common lasers are C02 based, with new

technology in the form of Diode Pumped Fiber lasers rapidly entering the marketplace. Lasers will cut a variety of different materials,

with the major strength in cutting metals thinner than ¼”. Some C02 laser have reflectivity issues on highly reflective materials such

as some grades of aluminum and copper, while the newer technology fiber lasers can cut reflective materials quite well. Lasers are

particularly strong on materials ¼” and thinner, yet the higher powered C02 systems can cut up to 1” steel, and ¾” stainless materials

with respectable tolerances

Abrasive Water Jet will cut almost anything…however for this comparison we will talk about the cutting of metals. Abrasive water jet

can cut any metal, and almost any thickness. The process is rather slow on hard materials and on thicknesses above about 1/8”, and

uses garnet as the abrasive cutting medium which adds some cost. Cut part accuracies will rival laser on thinner materials and will be

the best of all of the processes on thicker materials. The main advantages are the ability to cut anything, and the ability to cut without

a heat affected zone. The clear disadvantages are the slow cutting speeds (low productivity) as well as the associated high operating

costs.

Oxy-Fuel technology is limited primarily to cutting steel. Advantages are that the process is relatively simple, low cost from a capital

equipment point of view, and it is relatively common to have multiple oxy-fuel torches cutting simultaneously on a common cnc cutting

machine….making heavy plate cutting quite productive. Best material thickness range is from about ¾” to over 15” . Oxy-Fuel

torches are often mounted on the same cnc machine as plasma systems….dramatically expanding the thickness capability of these

cutting machines.

Direct comparisons:




The Perfect Cut

All fabricators that cut metal are looking for essentially the

same thing - THE PERFECT CUT. The perfect cut would have

the following properties:

• Low cost

• No metallurgical changes

• Repeatability

• Easy to operate

• Square cut edge angle

• Excellent tolerance

• No kerf lost

• High speed




Metal Cutting Methods

Unfortunately, this is not a perfect world! All metal cutting

methods have advantages and disadvantages.

Fundamentally, all metal cutting processes on the market

today fall into one of three categories:

• Mechanical (saw, shear, abrasive water jet, etc.)

• Chemical (oxy-fuel)

• Thermal (plasma or laser using non oxidizing gas)

• Chemical/Thermal (plasma or laser using oxygen)

Plasma could cut carbon steel at 6 times the speed of an oxy-fuel torch!

1980… 550

Amps, 85 ipm

Today…400

Amps, 150 ipm

Lower Power = Less smoke, less noise, less ultraviolet glare, less power cost

Plate cutting processes then……and now!




What is plasma?

• The first 3 states of matter are well known:

Solid, liquid, and gas

• By applying energy in the form of heat

it is possible to change states

• Water goes from a solid (ice) to a liquid

to a gas

• Adding more energy causes

gas to become ionized or more

electrically conductive

• Ionized gas transfers

energy from plasma

torch to the plate




What is plasma cutting?

• Plasma cutting torch

constricts and controls the

ionized gas stream or plasma

arc

• Process evolved from the TIG

welding process in the 1950’s

• Early plasma systems had

issues with cut quality,

consumable life, and

reliability




Relative Process Technology Levels

Plasma….Technology has been in commercial use since 1960’s • High Definition Cutting to over 2” thickness • Stainless and Aluminum to 6-1/4” • Hole accuracy improvement in last 3 years • Thin stainless quality improvements in last year • Dramatic “ease of use” improvements in last 5 years • Dramatic “cut to cut” productivity improvments in last 5 years • Air Plasma (low cost) inverter systems mechanized use has grown dramatically for lower tolerance / duty cycle applications • Beveling and structural shape cutting technology improvements in last 3 years

Plasma Technology is improving dramatically and rather quickly




Plasma technology continues to change

• True Hole technology • Advancements in stainless cutting • Consumable parts last 10x • Cut speeds are faster • Pierce capability is thicker • Ease of use, windows based cnc




-Entry level Air plasma systems, while less productive, can produce nice cut quality on low cost cnc machines. -Entry level machines as small as 2’ x 2’ can be purchased for less than $3k!

-Industrial, high definition plasma cutting systems can be configured in virtually any size, with multiple torch heads and beveling capability. On materials thicker than 3/16”…..and up to 2” on steel and 6” on aluminum and stainless….are by far the most productive plate cutting processes available.

Choices for Carbon Steel Cutting




Metal Cutting Methods

…This is 4 hours worth of plasma cutting on steel in the range of ¾” to 1-1/4”. High levels of productivity are the plasma advantage.





Oxy-Fuel….This technology, while it is not going away , has remained rather stagnant for over 50 years! •Oxy-fuel is often mounted on the same cnc machine as plasma. Some improvements in automating the gas flow and cut gas processes has taken place.

•Some torch height control technology improvements have been developed

This process is necessary for productive steel plate processing on thicknesses over 2”.




Oxyfuel

• Relatively simple steel cutting process with no major technological breakthroughs in many years

• Uses a fuel gas to preheat steel to its “kindling” temperature (1,800 degrees F) then activates a pure oxygen jet that uses an exothermic reaction to rapidly oxidize the steel




Oxyfuel

• Effective and decent cut quality from ¼” to 24” thickness

• Productive when small parts and multiple torches used simultaneously

• It takes 6 to 7 oxyfuel torches to equal one 260 amp plasma on 1/2” steel





Laser cutting….CO2 laser metal cutting technology has been well planted for around 25 years. Technology has continuously been evolving. We are in the midst of a major process change from C02 to Fiber Laser Technology. •Faster speeds and thicker materials will continue to be developed • Ease of use and process repeatability is continuously improving • Reduction of long term maintenance costs should be a major factor in switch from CO2 to Fiber technology • Ability to use Fiber Laser on more conventional machine designs….as well as for 3 dimensional structural shapes will be a major factor in change. • Power levels of Fiber Laser will bring productive plate thickness levels up.

Major Engineering and Technology Improvements are ongoing…this process will continue to evolve




Laser

• Excellent cut quality through the thickness range

• High productivity

• Better cut quality than plasma on holes with high aspect ratios (i.e.

less than a 1:1 diameter to thickness ratio)

• Higher powers enable cutting a broad thickness range with good

tolerance (up to 30mm or 1 ¼”)




Choices for Laser Cutting

Laser cutting systems best accuracy and productivity range is in the thin gauge to ¼” range on steel, stainless and aluminum. High wattage Lasers can cut steel up to 1”, however edge quality diminishes and the process becomes far less productive as compared to plasma. Cut part accuracy remains good up to the max thickness. Capital equipment costs are relatively high compared to the other processes

Many lasers are enclosed systems, as compared to open plasma, oxy-fuel and water jet tables….making material handling a bit more difficult. This is often solved with shuttle tables or moveable enclosures




BEAM DELIVERY LASER CAVITY

PUMP SOURCE

COOLING

CO2 Laser system:

Fiber Laser System:

Laser Technology Changes: C02 vs Fiber

Fundamental differences between C02 Laser and Fiber Laser




Energy Efficiency

CO2 (4kW) Fiber (2kW)

Total Cost of Ownership

Laser Technology Changes: C02 vs Fiber




Distinctive Value Proposition - Overview

Fiber Laser vs. CO2 Laser:

• Simplified laser table design and integration

• Reduced total cost of ownership

• Reduced operating cost

• Reduced service cost and intensity

• 3 times (3X) more energy efficient than CO2 (8-12% for C02 compared to 30% for

fiber laser)

• A 1.5kW fiber laser can do the work of a 3kW CO2 while using 83% less power

• Solid state technology for greater reliability/durability

• A more cost effective laser cutting solution




2004 2005 2006 2007 2008 2009 2010 2011 2012

0

1000

2000

3000

4000

5000

6000

Un

its

Fiber

CO2

While Fiber laser is a relatively new process in the laser cutting field, its acceptance has been growing steadily. Steady technology improvments and performance improvements are definitely tracking with the sales rates.

Fiber Laser Growth in the Market





Abrasive Water Jet….This technology will continue to evolve as well in the areas of: •Advancements in intensifier reliability (lower maintenance costs) • Increased water pressures will go hand in hand with reliability improvements • Improvement in water jet nozzle technology • Cut quality improvements in terms of edge angularity • Ease of use….expertise is transferring from the operator into the cnc and CAM software, similar to Plasma and Laser technologies

Let’s transition to Hypertherms Waterjet expert, Dave Dumas for details on this advancing technology…..




Waterjet

23

HyPrecision Waterjet……New Logo and colors!




Components

24




Types

25

• Pure water

• Used to cut soft materials

– Rubber

– Gaskets

– Seals

– Food

• Abrasive

• Used to cut hard materials

– Steel

– Stone

– Tile




How it works

26

• Cuts material through a rapid erosion process

• Erodes a very small area extremely quickly by using a high

powered, focused stream of water

• High pressure water (40,000 to 100,000 psi or 2,750 to 6,900 bar)

• Forced through a small orifice to create high velocity jet of water

• Jet travels at 2,200 mph, or 3,540 kph – three times faster than

speed of sound!




Cutting head

27




Cut quality

28

Excellent Poor




Waterjet pump

29

• Low pressure water assembly delivers filtered, low pressure

water to the intensifier




When to consider waterjet

30

Waterjet cutting may be the right solution when:

• Cut material cannot have Heat Affected Zone or mechanical stress

• Excellent edge finish is required

• Common-line cutting can save money by reducing material waste

• Repeatable tolerance range of 0.003” to 0.005” is required

• Wide variety of material types are cut




So…..which process?

Key closing points: -Laser is most productive on materials thinner than ¼”. Tolerances are excellent on most materials and thicknesses. Extremely productive on sheet metal. Medium to high operating cost, high capital equipment cost. -Oxy-Fuel is necessary for carbon steel thicker than 2”, does a good job down to about 3/8”. Is comfortable on the same cnc machine with plasma, is relatively inexpensive from a capital equipment view, higher than plasma in terms of operating cost. -Plasma is a universal process with the most metal applications, a wide capability and price range. Is by far the most productive process on carbon steel from ¼” through 2”, medium capital equipment cost, low operating cost. -Abrasive Water Jet can be considered a universal cutting product for all materials…including non-metals. It’s tolerances rival Laser. It is necessary where heat affected zones cannot be tolerated. Medium ot high capital cost, high operating cost.




Your metal cutting technology should be selected based on the following criteria:

•Material type and thickness range

•Accuracy requirements

•Productivity or throughput needs

•Plate sizes, available floor space

•Special operations required such as beveling or tube/pipe cutting

•finished part cost requirements

•Capital Equipment cost (Budget)

•Available technology

Rely on industry experts to assist with choosing the correct equipment and cutting technology…..

So…..which process?




Comparison of ½” mild steel cut samples

Lets look at a specific set of cut samples made from ½” A-36 grade steel. Each sample was drawn in CAD with a variety of features. The CAD (.dxf) file was then imported into ProNest CAM software for post processing…then sent to 5 different cnc machines for cutting.





Cutting Processes Used • Powermax105 at 105

amps

• MaxPro200 at 130 amps

• HPR260XD at 130 amps

• HFL030 Fiber Laser

• HyPrecision 60S abrasive waterjet

All samples are as cut, with the exception of minimal beads of dross removed (knocked off with scraper blade) from the air plasma sample.





For this comparison we will look at: • Edge appearance and angularity

• ½” nominal hole top and bottom dimensions and appearance

• 1-1/2” nominal hole top and bottom dimensions

• Estimated material and cutting cost for each process

-cost estimate includes utilities, labor, consumables. Does not include amortized capital equipment costs. Should be a good reference of the cost differences between cut processes





Simple shop floor tools used for measurement, digital calipers and protractor. Cost estimate for parts is generated by the CAM software (ProNest). All cuts done at book cutting specifications, speeds and settings. 5 different cnc machines were used, 5 machine operators input the cut files and cut the parts…..no special instructions.





Variables that should be expected? • Different cnc machine performance, accuracy, etc. • Different operators, chance of incorrect settings • Each process will show different levels of accuracy

Different variables in actual field / production use: • Normal process consumable parts wear • CNC machine mechanical wear, maintenance issues • Different steel chemistry / metalurgy




Measurement of a few cut features

Holes. It is very common for plasma cut holes to be tapered, (smaller at the bottom)….this taper is caused by the trailing angle of the arc as well as the shape of the arc. Recent technology in Hypertherm’s high definition class HPRXD systems minimize this taper dramatically as you will see.

Taper in holes with an air plasma, such as the Powermax105, can be minimized by using correct consumables, amperage, height control and cut speed techniques. The air plasma sample we will look at in the following slides is cut at “book” specs. If I could cut at lower power and adjust speed and height….the taper would be greatly improved!




Powermax105 using Air at 105 Amps

Measured Cut Part Specs, 105 amp air plasma .5” Nominal Hole (top/bottom): .501” / .440” (.059” taper) 1.5” Nominal Hole (top/bottom): 1.500” / 1.450” (.050” taper) Angularity on perimeter cut: +1.8 to + 2.0 degrees from 90.

Edge Appearance Minimal lag lines, dross free except for a few corner beads, some top edge rounding. Expect a case hardened (nitrided) edge approximately .006” thick.

Cut Time: 1:23




MaxPro200 using oxygen/air at 130 Amps

Measured Cut Part Specs, 130 amp oxygen plasma .5” Nominal Hole (top/bottom): .510” / .490” (.020” taper) 1.5” Nominal Hole (top/bottom): 1.510” / 1.495” (.015” taper) Angularity on perimeter cut: +1.8 to + 2.0 degrees from 90.

Edge Appearance Minimal lag lines, dross free, sharp top and bottom. Expect a slightly hardened (heat affected) edge. 100% weldable.

Cut Time: 1:06




HPR260XD with True Hole technology, 130 Amps

Measured Cut Part Specs, 130 amp high definition class plasma .5” Nominal Hole (top/bottom): .505” / .510” (.005” taper) 1.5” Nominal Hole (top/bottom): 1.502” / 1.495” (.007” taper) Angularity on perimeter cut: +1 degree from 90.


Cut Time: 0:53




HyIntensity Fiber Laser, HFL030, operating at 3kW

Measured Cut Part Specs, Fiber Laser .5” Nominal Hole (top/bottom): .510” / .502” (.008” reverse taper) 1.5” Nominal Hole (top/bottom): 1.510” / 1.502” (.008” reverse taper) Angularity on perimeter cut: -1 degree from 90.


Cut Time: 1:30




Hypertherm HyPrecision Abrasive Waterjet, Model 60S

Measured Cut Part Specs, Water Jet .5” Nominal Hole (top/bottom): .505” / .502” (.003” taper) 1.5” Nominal Hole (top/bottom): 1.505” / 1.500” (.005” taper) Angularity on perimeter cut: +.5 degree from 90.

Edge Appearance Almost non existent lag lines, dross free, sharp top and bottom. Unaffected edge from a metalurgy point of view.

Cut Time: 14:02





Process System Power Level Production Time Material Cost Production Cost Total Part Cost

Plasma Powermax 105 Amps 1:23 $1.21 $2.98 $4.19

Plasma MAXPRO 130 Amps 1:06 $1.21 $2.38 $3.59

Plasma HPR 130 Amps O2 Air 1:07 $1.21 $2.42 $3.62

Plasma HPR 130 Amps O2 Air (True Hole) 0:53 $1.21 $1.92 $3.12

Fiber Laser HyIntensity HFL0303 kW 1:30 $1.21 $3.24 $4.44

Waterjet HyPrecision 60,000 psi Quality 1 5:05 $1.21 $11.02 $12.22

Waterjet HyPrecision 60,000 psi Quality 5 14:02 $1.21 $30.40 $31.60

Fastest Cut: HPRXD with True Hole and Rapid Part Lowest Capital Cost: Powermax105 air plasma Best Edge Quality: HyPrecision Waterjet, with HyIntensity laser a close 2nd





MaxPro200, HPR260XD, HyIntensity Fiber Laser and HyPrecision Waterjet edge squareness





Discussion Points: - While this presentation depicts a fair comparison

of these processes on ½” steel, keep in mind that each process has its niche areas that will alter the outcome in terms of productivity, cut quality, operating cost, versatility, etc. of the final cut part.

Air Plasma: Low capital cost, easy to use and install. Perfect for the smaller welding shop, prototype shop, maintenance shop and hobbyist. Added benefit: can use a hand torch for manual cutting applications.

Fiber Laser: This process would dominate in terms of cut quality and productivity if this comparison was done on materials thinner than ¼”. It is the process of choice when high accuracy and productivity is needed in the thinner thickness ranges. Waterjet: By far the most versatile process as it can cut almost anything. For the shop that needs to cut metals, stone, glass, wood, plastics….this process can do them all. Softer materials cut faster, and at a much lower operating cost.





High Definition Plasma: Less expensive than waterjet and laser systems and has the ability to cut a wide thickness range of metals with excellent precision and productivity. Meets 95% of the tolerance and productivity requirements for steel fabricators worldwide. Its ability to be automated, taking the expertise out of the machine operators hands is a key to repeatable, high production needs in industry.

Convention Oxygen Plasma: This process is simpler, and less costly (purchase price) as compared to high definition plasma, laser and waterjet, yet has the plasma productivity advantage over other processes, especially on steel…..with respectable accuracy. A great choice for many metal fabrication operations.





A tough choice! Maybe you need each of the processes….many operations do. Rely on the experts at Hypertherm to help you make the correct decision.




Cutting applications for tube, pipe and

structural shapes

Thanks for listening!

Metal cutting questions?

metal cutting methods - didaktdidakt.no/stat/pm/plasma_oxy_waterjet_comparison.pdf · 2015. 2....

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