High power laser cutting welding

#12048 High Power Laser materials processing - Cutting and Welding of various metals

Ewa Ziolkowski, Susanna Friedel, Klaus Stolberg,

ALAB – LT

Jenoptik Laser GmbH

Authorized distributor and Application specialist for Czech Republic LINTECH, spol.s r.o. www.lintech.cz

Cutting

Welding

Workflow

Literature research Authorized distributor and Application specialist for Czech Republic LINTECH, spol.s r.o. www.lintech.cz

Task description “Cutting”

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Sample: •Stainless steel (1.4301)1.0mm and 2.0mm

•Aluminum (AlMg3) 1.0mm

•Copper 1.0mm

Quality requirements: •No burr

•Smooth cutting edge (small surface roughness)

•as fast as possible


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Summary

It is possible to cut stainless steel up to 2.0mm and aluminum up to 1.0mm with a sound cutting speed with the JenLas®fiber cw 1000 (Prototype) SM. Due to high reflectivity it was not possible to cut through copper 1.0mm. Other material thicknesses have not been

tested yet.

Highest possible cutting speed was 18m/min for 1.0mm steel, higher speed could not be

evaluated due to end of movement speed of x-y-stage.

Further evaluation have to be done for surface roughness .

There have not been any tests for aluminum and steel sheets thinner than 1.0mm due to limit of equipment (x-y-stage)!


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Laser JenLas®fiber cw 1000 SM

Laser: JenLas®fiber cw 1000 SM (Prototyp)

Specification: wavelength: 1070nm

pulse length: cw or modulated

repetition rate: cw… 5kHz power 1000W

M2 <=1.2


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Optical setup for cutting

Beam delivery: cutting head

Processing optics: fixed optics F120 K 125

leads to spot size of about 20µm Side remarks:

•processing gas (N2) with 3 different

nozzels (diameter 1.0mm, 1.2mm and 1.5mm)

•processing gas pressure: 16bar

•exhaust for ablation products

•All trials are done with non movable cutting head, movement of samples is

done by a x-y-stage (maximum movement

speed 18m/min)


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Overview of Cutting results with 1kW

Material and Nozzel size Best Cutting thickness [mm] Speed )*

[m/min]

Focal Quality position [mm]

Stainless 1.0 18 steel 1.0mm

-1 Good

Stainless 1.2 5 steel 1.0 mm

0 Burr


-2 Good


-1 Burr


-1 Burr


-2 Nearly no burr

Aluminium 1.2 18 1.0mm

0 Burr


-1 Good


0 Good

)* Remark: 18m/min is maximum moving speed of x-y-Stage, another equipment may lead to higher cutting speeds

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Overview of Cutting results 0.5kW

Material and Nozzel size thickness [mm]

Best Cutting Focal Quality Speed )* position [m/min] [mm]

Stainless 1.2 steel 1.0mm

10.0 -1 Burr)**

Stainless 1.0 steel 1.0 mm

9.0 -1 Good


8.0 0 Burr


9.0 0 Burr


3.0 0 Burr


2.1 -2 Burr


2.0 -2 Good

Aluminium 1.2 1.0mm

6.0 -1 Nearly no burr

Aluminium 1.0 1.0mm

7.0 -1 Burr


)** no burr at 9m/min!

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Detail photographs of cutting edges - Aluminum 1.0mm

Best quality v= 5.25m/min; no burr, smooth cutting edge

Highest cutting speed v=16m/min; burr, edges are not as smooth as with v=5.25m/min

Detail photographs of cutting edges - Steel 1.0 mm

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Highest cutting speed for steel plate

v= 18m/min No burr, smooth cutting edge

Highest cutting speed for aluminum plate

v=16m/min; burr, edges are not as

smooth as for steel plate 1.0 mm

Detail photographs of cutting edges - Steel 2.0 mm

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Highest cutting speed v=5m/min no burr, higher roughness as for steel

1.0mm

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Results of cutting various metals

Material and thickness

Best cutting Cutting speed )* speed with [m/min] best quality

[m/min]

Stainless steel 1.0mm

18.0 18.0

Stainless steel 2.0 mm

6.0 5.0

Aluminum 1.0mm

18 18


Aluminum and steel with a thickness of 1.0mm achieve the same cutting speed results. For aluminum there was more burr, grooves seam to be

more curved and edges are not as smooth as for steel.


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Cutting

Welding

Workflow

Literature research


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Task description “Welding”

Sample: •Aluminum 1.0mm (lap joint)

•Aluminum 5.0mm (blind welding)

Quality requirements: •smooth weld seam

•no discoloration

•no porosities

•no cracks


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Summary

It is possible to weld aluminum with JenLas® fiber cw 1000 (Prototype) SM. Welding depth was measured in varying the welding speed. A weld seam can be detected up to 13.5m/min. Maximum weld depth (2.6mm) was measured at

minimum used welding speed at 1.2m/min.


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Optical setup for welding

Beam delivery: laser processing head

Processing optics: fixed optics F200 K 310

leads to a spot diameter of about 30µm

Side remarks: •processing gas (N2) with a pressure of 3 bar

•reduced positioning accuracy due to usage of

6-axis-robot


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Overview of Welding Results Welding depth at different welding speeds

Seam

wid

th [

µm

]

weld

dep

th [

µm

]

Welding Seam geometry

1400 2800

1200 2400

1000 2000

800 1600

600 1200

400 800

200 400

0 0

0,0 2,0 4,0 6,0 8,0 10,0 12,0 14,0

welding speed [m/min]

Maximum welding depth is 2.6mm, maximum welding width is 1.2 mm both measured at minimum used welding speed of 1.2m/min. Depth and width scale with higher welding

speeds. At maximum possible welding speed, depth was 1.2mm and width 0.4mm

Detail photographs of welding depths and widths - variation of welding speed

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0.4mm 1.2mm

1.2mm

2.6mm

v=13.5m/min; smooth welding seam without porosities and cracks; very small reinforcement of welding seam,

aspect ratio 1:3; nail-head-shaped welding

seam v=1.2m/min, smooth welding seam without

SAME MAGNIFICATION (5x)! porosities and cracks, reinforcement comparable to that at 13.5m/min

aspect ratio ~1: 2 ;v-notch welding seam

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seam

dep

th [

µm

]

Detail photograph of welding depths and widths - variation of focal position

-z

z=0

+z

v=4.8m/min; focal position: -2mm; small reinforcement; no other irregularities

v=4.8m/min; focal position: +2mm; weld seam is collapsed at the top of sample, no other irregularities

Maximum welding depth was detected for z=-2.0mm!

2400

2000

1600

1200

800

400

0

welding depth

-4,0 -3,0 -2,0 -1,0 0,0 1,0 2,0

focal position z [mm]

Outlook

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Proposal of next steps:

Further cutting trials with titanium (0.5mm; 1.0mm), aluminum (2.0mm) and copper (0.5mm).

Further welding trials for titanium (0.5mm; 1.0mm – lap joint and blind welding – ) and

stainless steel (1.0mm – lap joint – ).

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Cutting

Welding

Workflow

Literature research

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Workflow for cutting trials

1. Setting of cutting head and x-y-stage

a. cutting head have to be fixed onto the x-y-stage and have to be loaded up into the x-y-stage control system

b. x-y-stage and carriage for sample have to be reset for further steps

c. cooling and fiber have to be adjusted to the cutting head

d. cooling for JenLas® fiber cw 1000 (prototype) and laser itself have to be adjusted

e. cutting process gas have to be installed

If nothing is prepared this will take about 3 hours.

2. Setting of focal position

3. Adjustment of sample

4. Execution of trials

5. Collection of trial data

6. Post processing and evaluation

2. – 5. can take up to 3

hours for one material in one thickness

Duration depends on requirements of customer and type of application. Can take about 4

hours up to 5 hours.

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Workflow for welding trials

1. Setting of cutting head and x-y-stage

a. cutting head have to be fixed onto the robot and have to be loaded up into the robot control system

b. robot has to be reset for further steps

c. cooling and fiber have to be adjusted to the processing head

d. cooling for JenLas® fiber cw 1000 (prototype) and laser itself have to be adjusted

e. protection gas have to be installed

If nothing is prepared this will take about 3 hours.

2. Setting of focal position

3. Adjustment of sample

4. Execution of trials

5. Collection of trial data

6. Post processing and evaluation

Duration depends on requirements of customer and type of application. Can take about 6 hours up to 10 hours.

Similar to Workflow of cutting trials BUT post processing takes much more time!!!

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Workflow of post processing of welding trials

1. Grinding and polishing of samples

a. All samples are ground in several steps; grain size became smaller with every

steps. Depending on requirements of customer and type of application the

samples also have to be polished.

b. after each grinding and polishing step the sample and the grinding machine (for polishing also the polishing disc) have to be cleaned with water carefully.

2. Etching

a. For each material there is a special etching agent. For stainless steel (1.4301)

Adler etching agent was used (contains hydrochloric acid), for aluminum Keller

etching agent or sodium hydroxide solution was used

b. Success of Etching always depends on residence time.

3. Microscopy

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Cutting

Welding

Workflow

Literature research

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Literature research “ Cutting with 1kW fiber laser SM”

Material and Highest thickness cutting

speed [m/min]

Spot size [µm]

Stainless ~24m/min steel 1.0mm

10

Stainless ~11m/min steel 2.0 mm

10

St1203 15m/min 1.0mm

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Aluminum 16m/min AlMg3 1.0mm

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IWS Dresden

IPG 1kW SM fiber laser

Jenoptik Laser GmbH (Mai-Jul. 2012)

JenLas® fiber cw 1000 (prototype) SM

Material and thickness

Best cutting Spot size speed )* [µm] [m/min]

Stainless steel 1.0mm

18.0 20

Stainless steel 2.0 mm

6.0 20

Aluminum AlMg31.0mm

18 20

)* Remark: 18m/min is maximum moving speed of x-y-stage, another equipment may lead to higher cutting speeds

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Literature research “ Welding with 1kW fiber Laser SM”

Material and Welding thickness speed

[m/min]

Weld depth Spot size [mm] [µm]

Aluminum 1.2 AlMg3

2.6 30

…

IWS Dresden, BIAS Bremen

IGP 1kW SM fiber laser – blind welding

Jenoptik Laser GmbH (Jul. 2012)

JenLas® fiber cw 1000 (prototype) SM – blind welding

Material and Welding thickness speed

[m/min]

Weld depth Spot size [mm] [µm]

Stainless 1.0 steel (IWS)

2.4 180

Stainless 7.5 steel (IWS)

1.4 180

Stainless 10 steel (BIAS)

2.5 20

Aluminum 1 AlMg3 (IWS)

2.6 35


2.4 35


1.8 35

Documents

High power laser cutting welding