10. laser beam welding - 123seminarsonly.com...1961 manufacturing of the first hene lasers and nd:...

10.

Laser Beam Welding

10. Laser Beam Welding 134

2005

The term laser is the abbreviation for ,,Light Amplification by Stimulated Emission of Radia-

tion”. The laser is the further development of the maser (m=microwave), Figure 10.1. Al-

though the principle of the stimulated emis-

sion and the quantum-mechanical fundamen-

tals have already been postulated by Einstein

in the beginning of the 20th century, the first

laser - a ruby laser - was not implemented

until 1960 in the Hughes Research Laborato-

ries. Until then numerous tests on materials

had to be carried out in order to gain a more

precise knowledge about the atomic structure.

The following years had been characterised

by a fast development of the laser technology.

Already since the beginning of the Seventies

and, increasingly since the Eighties when the

first high-performance lasers were available,

CO2 and solid state lasers have been used

for production metal working.

The number of the annual

sales of laser beam sources

has constantly increased in

the course of the last few

years, Figure 10.2.

The application areas for the

laser beam sources sold in

1994 are shown in Figure

10.3. The main application

areas of the laser in the field

of production metal working

are joining and cutting jobs.

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History of the Laser

1917 postulate of stimulated emission by Einstein

1950 physical basics and realisation of a maser (Microwave Amplification by Stimulated Emission of Radiation) by Towens, Prokhorov, Basov

1954 construction of the first maser

1960 construction of the first ruby laser (Light Amplification by Stimulated Emission of Radiation)

1961 manufacturing of the first HeNe lasers and Nd: glass lasers

1962 development of the first semiconductor lasers

1964 nobel price for Towens, Prokhorov and Basov for their works in the field of masers construction of the first Nd:YAG solid state lasers and CO gas lasers

1966 established laser emission on organic dyes

since increased application of CO and solid state laser

1970 technologies in industry

1975 first applications of laser beam cutting in sheet fabrication industry

1983 introduction into the market of 1-kW-CO lasers

1984 first applications of laser beam welding in industrial serial production

work out of

2

2

2

Figure 10.1

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3

10 €

2

1.5

1

0.5

0

9

Japan and South East AsiaNorth AmericaWest Europe

1986 1988 1990 1992 1994 1996 1998 2000

Figure 10.2


2005

The availability of more efficient laser beam sources opens up new application possibilities

and - guided by financial considerations - makes the use of the laser also more attractive,

Figure 10.4.

Figure 10.5 shows the

characteristic properties

of the laser beam. By rea-

son of the induced or

stimulated emission the

radiation is coherent and

monochromatic. As the

divergence is only 1/10

mrad, long transmission

paths without significant

beam divergences are

possible.

Inside the resonator, Fig-

ure 10.6, the laser-active medium (gas molecules, ions) is excited to a higher energy level

(“pumping”) by energy input (electrical gas discharge, flash lamps).

During retreat to a lower

level, the energy is re-

leased in the form of a light

quantum (photon). The

wave length depends on

the energy difference be-

tween both excited states

and is thus a characteris-

tic for the respective la-

ser-active medium.

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inscribe20,5%

microelectronics

5,4%

welding18,7%

drilling1,8%

others9,3%

cutting44,3%

Figure 10.3

br-er10-04e.cdr

lase

r po

we

r

CO2

Nd:YAG

diode laser0

1

2

3

4

5

10

20

kW

40

19

70

19

75

19

80

19

85

19

95

19

90

20

00

Figure 10.4


2005

A distinction is made be-

tween spontaneous and

induced transition. While

the spontaneous emission

is non-directional and in

coherent (e.g. in fluores-

cent tubes) is a laser beam

generated by induced

emission when a particle

with a higher energy level

is hit by a photon. The re-

sulting photon has the

same properties (fre-

quency, direction, phase)

as the exciting photon (“coherence”). In order to maintain the ratio of the desired induced

emission I spontaneous emission as high as possible, the upper energy level must be con-

stantly overcrowded, in comparison with the lower one, the so-called “laser-inversion”. As

result, a stationary light wave is formed between the mirrors of the resonator (one of which is

semi-reflecting) causing parts of the excited laser-active medium to emit light.

In the field of production metal working, and particularly in welding, especially CO2 and

Nd:YAG lasers are applied for their high power outputs. At present, the development of diode

lasers is so far advanced

that their sporadic use in the

field of material processing

is also possible. The indus-

trial standard powers for

CO2 lasers are, nowadays,

approximately 5 - 20 kW,

lasers with powers of up to

40 kW are available. In the

field of solid state lasers

average output powers of

up to 4 kW are nowadays

obtainable.

© ISF 2002br-er10-05e.cdr

Characteristics of Laser Beams

light bulb Laser

E2

E1 exitedstate

groundstate

polychromatic

incoherent

large divergence

(multiple wave length)

(not in phase)

0,46"

0,94"

monochromatic

coherent

small divergence

(in phase)

induced emission

Figure 10.5


Laser Principle

energy source

energy source

resonator

fully reflecting mirror

R = 100%

partially reflectingmirrorR < 100%

las

er

be

am

active laser medium

Figure 10.6


2005

In the case of the CO2 laser, Figure 10.7, where the resonator is filled with a N2-C02-He gas

mixture, pumping is carried out over the vibrational excitation of nitrogen molecules which

again, with thrusts of the

second type, transfer their

vibrational energy to the

carbon dioxide. During the

transition to the lower en-

ergy level, CO2 molecules

emit a radiation with a

wavelength of 10.6 µm.

The helium atoms, finally,

lead the CO2 molecules

back to their energy level.

The efficiency of up to

15%, which is achievable with CO2 high performance lasers, is, in comparison with other la-

ser systems, relatively high. The high dissipation component is the heat which must be dis-

charged from the resonator. This is achieved by means of the constant gas mixture circula-

tion and cooling by heat exchangers. In

dependence of the type of

gas transport, laser sys-

tems are classified into

longitudinal-flow and trans-

verse-flow laser systems,

Figures 10.8 and 10.9.

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radio frequency high voltage exitaion

laser beam

cooling water cooling water

laser gas

gas circulation pump

vakuum pump

laser gas:CO : 5 l/h

He: 100 l/hN : 45 l/h

2

2

Figure 10.8


Energy Diagram of CO Laser2

0,6

eV

0,4

0,3

0,2

0,1

0

en

erg

y

0,288 eV

2

1 001 0,290 eV

100

002

LASER = 10,6 µmλ

transmission ofvibration energy

thrust of second type

thrust of first type

∆E = 0,002 eV

transition withoutemission

discharge through thrust with helium

N2 CO2

0000

Figure 10.7


2005

With transverse-flow laser systems of a compact design can the multiple folding ability of

the beam reach higher output powers than those achievable with longitudinal-flow sys-

tems, the beam quality, however, is worse. In d.c.-excited systems (high voltage), the elec-

trodes are positioned inside the resonator. The interaction between the electrode material

and the gas molecules causes electrode burn-off.

In addition to the wear of the electrodes, the burn-off also entails a contamination of the laser

gas. Parts of the gas mixture must be therefore exchanged permanently. In high-frequency

a.c.-excited systems the electrodes are positioned outside the gas discharge tube where

the electrical energy is ca-

pacitively coupled. High

electrode lives and high

achievable pulse frequen-

cies characterise this kind

of excitation principle. In

diffusion-cooled CO2 sys-

tems beams of a high qual-

ity are generated in a mini-

mum of space. Moreover,

gas exchange is hardly

ever necessary.

The intensity distribution is

not constant across the la-

ser beam. The intensity dis-

tribution in the case of the

ideal beam is described by

TEM modes (transversal

electronic-magnetic). In the

Gaussian or basic mode

TEM00 is the peak energy in

the centre of the beam

weakening towards its pe-

riphery, similar to the Gaus-

sian normal distribution. In


Laser Beam Qualitiy

0<K<1

with d d. d. =c.σ σ 0.

0 F FΘ = Θ = Θ

ΘF

d0

unfocussed beam focussed beam

f2,57"

dF

K = .

2 1 λ

π dσ σΘ

Figure 10.10

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Cooling water

cooling water

laser gas:CO : 11 l/h

He: 142 l/hN : 130 l/h

2

2

laser gasend mirror

turningmirrors

gas circulationpump

mirror(partially reflecting)

gas discharge

laser beam

Figure 10.9


2005

practice, the quality of a laser beam is, in accordance with DIN EN 11146, distinguished by

the non-dimensional beam quality factor (or propagation factor) K (0...1), Figure 10.10.

The factor describes the ratio of the distance field divergence of a beam in the basic mode to

that of a real beam and is

therefore a measure of a

beam focus strength. By

means of the beam quality

factor, different beam

sources may be compared

objectively and quanti-

taively.

The CO2 laser beam is

guided from the resonator

over a beam reflection mir-

ror system to one or sev-

eral processing stations,

Figures 10.11 and 10.12.

The low divergence allows

long transmission paths. At

the processing station is

the beam, with the help of

the focussing optics,

formed according to the

working task. The relative

motion between beam and

workpiece may be realised

in different ways:

- moving workpiece, fixed optics

- moving (“flying”) optics

- moving workpiece and moving optics (two handling facilities).

br-er10-11e.cdr

resonator

LASER

work piece manipulator

absorber

partiallyreflecting

mirror

shutter

work piece

endmirror

beam creationfocussing system

beam divergence mirror

beam transmissiontube

Figure 10.11

Figure 10.12

© ISF 2002br-er10-12e_f.cdr

CO Laser Beam Welding Station2


2005

In the case of the CO2 laser,

beam focussing is normally

carried out with mirror op-

tics, Figure 10.13. Lenses

may heat up, due to ab-

sorption, especially with

high powers or contamina-

tions. As the heat may be

dissipated only over the

holders, there is a risk of

deformation (alteration of

the focal length) or destruc-

tion through thermal over-

loading.

In the case of solid state laser, the normally cylindrical rod serves only the purpose to pick

up the laser-active ions (in the case of the Nd:YAG laser with yttrium-aluminium-garnet

crystals dosed with Nd3+ ions), Figure 10.14. The excitation is, for the most part, carried out

using flash or arc lamps, which for the optimal utilisation of the excitation energy are ar-

ranged as a double ellipsoid; the rod is positioned in their common focal point. The achieved

efficiency is below 4%. In the meantime, also diode-pumped solid state lasers have been in-

troduced to the market.

The possibility to guide the

solid-state laser beam over

flexible fibre optics makes

these systems destined for

the robot application,

whereas the CO2 laser ap-

plication is restricted, as its

necessary complex mirror

systems may cause radia-

tion losses, Figure 10.15. © ISF 2002br-er10-14e.cdr

Principle Layout of Solid State Laser

laser rod

laser beam

partially reflectingmirror (R < 100%)

flash lamps

end mirror (r = 100%)

Figure 10.14


Focussing Optics

reflective90°-mirror optic

α

Figure 10.13


2005

Some types of optical fibres allow, with fibre diameters of ≤ 1 mm bending radii of up to 100

mm. With optical switches a multiple utilisation of the solid state laser source is possible; with

beam splitters (mostly with a fixed splitting proportion) simultaneous welding at several proc-

essing stations is possible. The disadvantage of this type of beam projection is the impaired

beam quality on account of multiple reflection.

The semiconductor or

diode lasers are charac-

terised by their mechanical

robustness, high efficiency

and compact design, Fig-

ure 10.16. High perform-

ance diode lasers allow the

welding of metals, although

no deep penetration effect

is achieved. In material

processing they are there-

fore particularly suitable for

welding thin sheets.

Energy input into the workpiece is carried out over the absorption of the laser beam. The

absorption coefficient is,

apart from the surface qual-

ity, also dependent on the

wave length and the mate-

rial. The problem is that a

large part of the radiation is

reflected and that, for ex-

ample, steel which is ex-

posed to wave lengths of

10.6 µm reflects only 10%

of the impinging radiation,

Figure 10.17. As copper is

a highly reflective metal

© ISF 2002br-er10-16e_f.cdr

Diode Laser

Figure 10.16

© ISF 2002

Nd:YAG Laser Beam Welding Station

br-er10-15e_f.cdr

Figure 10.15


2005

with also a good heat conductivity, it is frequently used as mirror material.

Intensity adjustment at the

working surface by the fo-

cal position with a simulta-

neous variation of the

working speed make the

laser a flexible and contact-

less tool, Figure 10.18. The

methods of welding and

cutting demand high inten-

sities in the focal point,

which means the distance

between focussing optics

and workpiece surface must

be maintained within close

tolerances. At the same

time, highest accuracy and

quality demands are set on

all machine components

(handling, optics, resonator,

beam manipulation, etc.).

Steel materials with treated

surfaces reflect the laser

beam to a degree of up to

95%, Figures 10.19 - 10.22.

When metals are welded with a low-intensity laser beam (I ≤ 105 W/cm2), just the workpiece

surfaces and/or edges are melted and thus thermal-conduction welding with a low deep-

penetration effect is possible. Above the threshold intensity value (I ≤ 106 W/cm2) a phase

transition occurs and laser-induced plasma develops. The plasma, whose absorption char-

acteristics depend on the beam intensity and the vapour density, absorbs an increased

quantity of radiation.

Figure 10.18

br-er10-18e.cdr

10 10 10 10 s 10-8 -6 -4 -2 0

10

W/cm

10

10

10

10

10

10

10

2

8

7

6

5

4

3

po

wer

de

ns

ity

acting time

energy density [J/cm²]

drilling102

100

104

106

remeltingcoating

glaze

shock hardening

weldingcutting

martensitic hardening

Figure 10.17


Wave Length Absorption Dependent of Various Materials

absorp

tion A

0,30

0,25

0,20

0,15

0,10

0,05

0

wave length λ0,1 0,2 0,3 0,5 0,8 1 2 4 5 8 10 µm 20

Al

Cu

Ag

Mo

Fe

Stahl

Nd:YAG-laser

CO -

laser2


2005

A vapour cavity forms and

allows the laser beam to

penetrate deep into the

material (energy input

deep beyond the work-

piece surface); this effect is

called the “deep penetra-

tion effect”. The cavity

which is moved though the

joining zone and is pre-

vented to close due to the

vapour pressure is sur-

rounded by the largest part

of the molten metal. The residual material vaporises and condenses either on the cavity side

walls or flows off in an ionised form. With suitable parameter selection, an almost complete

energy input into the workpiece can be obtained.

Figure 10.20


Principle of Laser Beam Welding

heat conductingwelding

deep penetrationwelding

laser beam

molten pool

soldifiedweld metal

laser beam

keyhole(vapour-/plasma cavity)

metal vapourblowing away

laser-inducedplasma

molten pool

soldifiedweld metal

Figure 10.19


Calculated Intensity Threshold forProducing a Laser-Induced Plasma

10 10 10 s 10-10 -8 -6 -2

las

er

inte

ns

ity

I

radiation time t

10

W/cm

10

10

10

10

10

2

8

7

6

5

steel

r = 100 µm

= 10.6 µmF

l

A = 0,1

A = 1

working zone

plasma threshold

plasma shielding

Figure 10.21


Reflection and Penetration Depthin Dependence on Intensity

10 10 W/cm 105 6 2 7

laser intesity I

pen

etr

ati

on

de

pth

tre

fle

cti

on

R

100

%

60

40

20

0

4

mm

2

1

0

material: steel

wave length 10,6 µmlaser power: 2 kWwelding speed: 10 mm/sworking gas: helium

λ:


2005

However, in dependence of the electron density in the plasma and of the radiated beam in-

tensity, plasma may detach from the workpiece surface and screen off the working zone. The

plasma is heated to such a high degree that only a fraction of the beam radiation reaches the

workpiece. This is the rea-

son why, in laser beam

welding, gases are applied

for plasma control. The

gases’ ionisation potential

should be as high as pos-

sible, since also the forma-

tion of “shielding gas plas-

mas” is possible which

again decreases the en-

ergy input.

Only a part of the beam energy from the reso-

nator is used up for the actual welding process,

Figure 10.23. Another part is absorbed by the

optics in the beam manipulation system, an-

other part is lost by reflection or transmission

(beam penetration through the vapour cavity).

Other parts flow over thermal conductance into

the workpiece.

Figure 10.24 shows the most important advan-

tages and disadvantages of the laser beam

welding method.


Interaction Between Laser Beam and Material

Transformation of electromagnetic energy into thermal energywithin nm range at the surface of the work piece by

stimulation of atoms to resonant oscillations

"normal" absorption: "abormal" absorption:

−

−

−

−

−

−

−

depandent on laser beam intensity:

I < 10 W/cm²

dependent on wave length

dependent on temperature

dependent on material

absorption at solid or liquid surface: A < 30%

formation of a molten bath with low

penetration depth

6 −

−

−

−

dependent on laser intesity:

I 10 W/cm²

heating up to temperature of evaporation and formation of a metal

vapour plasma

almost complete energy entry through absorption by plasma: A > 90%

formation of a vapour cavity

≥6

heat conducting welding deep penetration welding

Figure 10.22

br-er10-23e.cdr

Scheme of Energy Flow

beam energy

diagnostics

beam transmissionfocussing system

reflection

transmission

heat convectionheat conductionmetal vapourplasma

recombination

work piece

fusion energy

0-2,5%

2,5-12,5%

ca. 5%

ca. 10%

ca. 40%

85-95%

10-15%ca. 30%

Figure 10.23


2005

Penetration depths in dependence of the beam power and welding speed which are

achievable in laser beam welding are depicted in Figure 10.25. Further relevant influential

factors are, among others,

the material (thermal con-

ductivity), the design of

the resonator (beam qual-

ity), the focal position and

the applied optics (focal

length; focus diameter).

Figure 10.26 shows several

joint shapes which are typi-

cal for car body production

and which can be welded

by laser beam application.

The high cooling rate during laser beam

welding leads, when transforming steel mate-

rials are used, to significantly increased

hardness values in comparison with other

welding methods, Figure 10.27. These are a

sign for the increased strength at a lower

toughness and they are particularly critical in

circumstances of dynamic loads.

The small beam diameter demands the very

precise manipulation and positioning of the

workpiece or of the beam and an exact weld

preparation, Figure 10.28. Otherwise, as re-

sult, lack of fusion, sagged welds or concave

root surfaces are possible weld defects.


Advantages and Disadvantagesof Laser Beam Welding

advantages disadvantages

process

work piece

installation

- high power density- small beam diameter- high welding speed- non-contact tool- welding possibleatmosphere

- high reflection at metallic surfaces- restricted penetration depth ( 25 mm)

- minimum thermal stress- little distortion- completely processed components- welding at positions difficult to access- different materials weldable

- expensive edge preparation- exact positioning required- danger of increased hardness- danger of cracks- Al, Cu difficult to weld

- expensive beam transmission and forming- power losses at optical devices- laser radiation protection required- high investment cost- low efficency (CO -Laser: < 20%, Nd:YAG: < 5%)2

- short cycle times- operation at several stations possible- installation availability > 90%- well suitable to automatic function

Figure 10.24

br-er10-25e.cdr

Penetration Depths

pene

tra

tion

de

pth

pe

netr

atio

n d

ep

th

welding speed

welding speed

28

mm

20

16

12

8

4

0

15

mm

5

0

0 0,6 1,2 1,8 m/min 3,0

0 1 2 3 4 5 6 7 m/min 9

laser power:

0,2% C-steelCO -laser2

(cross flow)

X 5 CrNi 18 10CO -laser2

(axial flow)

laser power:

15 kW

8 kW

1,5 kW

6 kW4 kW

6 kW4 kW2 kW

1 kW

10 kW

Figure 10.25


2005


Welding Defects

edge preparation misalignment

gap mispositioning

(e 0,1 x plate thickness)≤

(a 0,1 x plate thickness)≤

beam

br-er10-27e_f.cdr

laser beam weld

submerged arc weld

hard

ne

ss

distance from the weld centre

weld submerged arc weld

MAZ

MAZ MAZ

MAZWMA

0 12

500

HV 0,4

Figure 10.27

Figure 10.28

br-er10-26e.cdr

butt weld

lap weld at overlap joint

fillet weld at overlap joint

flanged weld at overlap joint

Figure 10.26


2005

br-er10-30e.cdr

backward wire feedingforward wire feeding

welding direction

filler wire filler wirelaser beam laser beam

gas gas

plasma plasma

work piece work pieceweld metal weld metal

molten pool molten poolkeyhole keyhole

Figure 10.30

Caused by the high cooling rate and, in connection with this, the insufficient degassing of the

molten metal, pore formation may occur during laser beam welding of, in particular, thick

plates (very deep welds) or while carrying out welding-in works (insufficient degassing over

the root), Figure 10.29.

However, too low a weld speed may also cause pore formation when the molten metal picks

up gases from the root side.

The materials that may be

welded with the laser reach

from unalloyed and low-

alloy steels up to high qual-

ity titanium and nickel

based alloys. The high

carbon content of the

transforming steel materials

is, due to the high cooling

rate, to be considered a

critical influential factor

where contents of C >

0.22% may be stipulated as

the limiting reference value.

Aluminium and copper

properties cause problems

during energy input and

process stability. Highly

reactive materials demand,

also during laser beam

welding, sufficient gas

shielding beyond the solidi-

fication of the weld seam.

The sole application of

working gases is, as a rule,

not adequate.


Porosity

v = 0,7 m/minw v = 0,9 m/minw v = 1,5 m/minw

material: P460N (StE460), s = 20 mm, P = 15 kw

Figure 10.29


2005

br-er10-31e.cdr

without filler wire with filler wire

filler wire: Sg2d = 0,8 mmw

gap: 0 mmv = 1,6 m/minw

gap: 0,5 mmwire: SG-Ni Cr21 Fe18 Mo

v = 1,0 m/min

d = 1,2 mmw

w

weld zoneweld zone

increase of gapbridging ability

material:

gap:

S380N (StE 380)0,5 mm

P = 8,3 kW

V = 3 m/min

E = 166 J/mins = 4 mm

L

W

S

Possibility ofmetallurgical influence

material combination:

10CrMo9-10/ X6CrNiTi18-10P = 5,0 kWL

Figure 10.31

The application of laser beam welding may be extended by process variants. One is laser

beam welding with filler wire, Figures 10.30 and 10.31 which offers the following advantages:

- influence on the me-

chanic-technological prop-

erties of the weld and fu-

sion zone (e.g. strength,

toughness, corrosion, wear

resistance) over the metal-

lurgical composition of the

filler wire

- reduction of the demands

on the accuracy of the weld

preparation in regard to

edge misalignment, edge

preparation and beam mis-

alignment, due to larger

molten pools

- “filling” of non-ideal, for example, V-shaped groove geometries

- a realisation of a defined weld reinforcement on the beam entry and beam exit side.

The exact positioning of the

filler wire is a prerequisite

for a high weld quality and a

sufficient dilution of the mol-

ten pool through which filler

wire of different composition

as the base can reach right

to the root. Therefore, the

use of sensor systems is

indispensable for industrial

application, Figure 10.32.

The sensor systems are to

take over the tasks of

- process control,

br-er10-32e.cdr

0.1 mm 0.2 mm 0.3 mm 0.4 mm 0.5 mm 0.6 mm

with sensing device; fill factor 120 %

without sensing device; wire speed v = 4 m/min constantD

KB 4620/1220:1

10/92

Probe OS1-6A

KB 4621/720:1

10/92

Probe OS1-1B

KB 4621/1520:1

10/92

Probe OS1-4C

KB 4620/1720:110/92

Probe OS1-5C

KB 4621/920:1

10/92

Probe OS1-2B

KB 4621/1220:1

10/92

Probe OS1-3B

KB 4620/920:1

10/92

Probe MS1-6C

KB 4620/620:110/92

Probe MS1-5A

KB 4620/3820:1

10/92

Probe MS1-1C

KB 4620/420:1

10/92

Probe MS1-4C

KB 4620/020:1

10/92

Probe MS1-3A

KB 4620/4120:1

10/92

Probe MS1-2B

1 mm

Figure 10.32


2005

- weld quality as surance

- beam positioning and joint tracking, respectively.

The present state-of-the-art is the further development of systems for industrial applications

which until now have been tested in the laboratory.

Welding by means of solid state lasers has, in the past, mainly been applied by manufactur-

ers from the fields of precision mechanics and microelectronics. Ever since solid state lasers

with higher powers are available on the market, they are applied in the car industry to an ever

increasing degree. This is due to their more variable beam manipulation possibilities when

comparing with CO2 la-

sers. The CO2 laser is

mostly used by the car in-

dustry and by their ancil-

lary industry for welding

rotation-symmetrical mass-

produced parts or sheets.

Figure 10.33 shows some

typical application exam-

ples for laser beam weld-

ing.

Practical Application Fields


plant and apparatus engineering- seal welds at housings

- measurement probes

aerospace industry

- engine components

- instrument casesautomotive industry

- gear parts

- body-making

- engine components

(cog-wheels, planet gears)

(bottom plates, skins)

(tappet housings, diesel engine

precombustion chambers)

medical industry

- heart pacemaker cases

- artificial hip joints

electronic industry

- PCBs

- accumulator cases

- transformer plates

- CRTs

steel industry

- pipe production

- vehicle superstructures

- continuous metal strips

- tins

Figure 10.33

10. laser beam welding - 123seminarsonly.com...1961 manufacturing of the first hene lasers and nd:...

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