Diode laser systems for materials processing applications Gary Broadhead – Laser Lines Ltd Introduction to diode lasers State-of-the-art high power diode lasers Applications Conclusion

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Diode Laser - Single Emitters and Bars A high power diode laser system comprises a number of individual semiconductor laser devices (usually based on GaAs wafers) whose beams are optically combined to achieve the required total power. These individual elements are either “Single Emitter” or “Bar” devices. A bar is a monolithic linear array of devices fabricated on the wafer. The wavelength of laser diode systems is usually 9xx nm (915/940/980)

Single Emitter

Bar

Power

10 W

150 W

Efficiency

50 %

30 – 40 %

Cooling

Passive

Passive or active

MTBF

> 500,000 hours

Up to 80,000 hours

Passively cooled bar (above)

Single Emitter Actively cooled bars Laser Lines Ltd

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Diode Laser - Single Emitters and Bars Typical fibre-coupled single emitter based submodule containing 10 to 16 devices inside. Output power up to 120 Watts at 940/980nm. Air cooled. Size approx 12cm x 5cm x 2.5cm Multiple SE modules can be readily combined to provide laser powers of around 1kW. Typical bar based sub-module (“Stack”) in this case comprising 6 bars. A 10 bar stack could deliver 1.5kW of laser power. Size approx 5cm x 5cm x 2cm Multiple stacks can be combined to provide laser powers in excess of 12kW.

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Basics: Laser Beam Source Modular Product Coupling methods: wavelength and polarisation Polarisation coupling

Easy upgrade in output power Beam geometry & intensity distribution readily adapted Diode laser stack (or SE module)

Laser diodes Wavelength coupling Laser Lines Ltd

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Beam Quality Trends 150 mm mrad

Fiber Diameter

Laser power [W]

100 mm mrad

60 mm mrad

40 mm mrad 30 mm mrad

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Market Movement for Diode Lasers 1000

Beam quality [mm m mrad]

Diode Applications since 1999 Diode Applications since 2002

100

Diode Applications since 2004 Cutting 10 10

100

1000 Laser power [W]

Limits in Power and Beam quality Diode laser systems 2007

10000

Diode Applications since 2007 Diode Applications 2009 Future Applications

Diode laser systems 2009 Laser Lines Ltd

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Current top end specifications 4,000 W diode laser with a beam quality of 30 mm mrad (comparable with lamp pumped YAG)) Diode laser with 10,000 W laser power at the end of a 1mm fiber (100mm mrad) 2,300 W diode laser the size of an industrial PC Compact packaging: 10,000 W in less than a square meter footprint 5 year warranty on diode laser elements

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Excellent Beam Quality and Power

specification p max. output power beam quality laser light cable

2,000 W

3,000 W

4,000 W

5,000 W

20 mm∙mrad

30 mm∙mrad

40 mm∙mrad

400 µm, NA 0.1

300 µm, NA 0.2 or 600 µm, NA 0.1

400 µm, NA 0.2

min. spot at f = 100 mm

0.2 mm

0.3 mm

0.4 mm

power consumption, max.

7.5 kW

10 kW Laser Lines Ltd

13 kW

17 kW 8

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Typical System Options Typical system options Visible pilot laser p to 6 fibre outputs p Up and time-share beam switch Cover slide cassette Fiber length up to 100 m Application specific optics Closed loop pyrometer control Dust and humidity protection Galvanometer scan heads

Control system upgrade Profibus, Interbus, Device Net, Profi Net, Ethernet connection PC control: LL Control Software Separate control panel Teleservice via safe VPN connection Wavelength stabilization for pump applications Extended programming and interaction functionality

Easy integration in systems for production. Ease of use and service. Laser Lines Ltd

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Optics Modular optics for flexible adaptation to any process R b td Robust design i ffor hi high h power processes Straightforward solutions for complex tasks Customer specific focus geometries for almost every requirement Optics for welding, brazing and cladding Compatible with industrial standards

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Specialty Spots

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System integration The fibre coupled diode laser is simple to integrate and is particularly suited to robotic applications.

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Applications:: Spot Requirements Applications

Beam quality [mm m mrad]

1000

Rectangular spot: 3 x 3 – 10 x 60 mm Spot: 1.5 – 3.5 mm

100

Spot: 1 - 6 mm Spot: 0.6 - 3 mm Spot: 0.3 – 0.8 mm 10 10

100

Spot: 0.6 - 2 mm

1000 Laser power [W]

10000

Spot: 0.2 0 2 – 0.6 0 6 mm

Spot: 0.5 - 5 mm

Diode Laser can meet most of the spot requirements Laser Lines Ltd

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Heat Conduction Welding: steel 

Diode lasers are used in various application areas of mass production



Heat conduction welding of stainless steel sinks



Welding of bellows



Welding of battery housings



Tube welding

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Absorption of laser radiation: Al



High absorption peak of aluminum att 800 – 900 nm



Degree of absorption A [%]: Nd:YAG => 5% Diode => 14%

Source: Audi, C.Ebert EALA 2009 Laser Lines Ltd

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Brazing Related process of welding with filler wire For requirements of high strengths and small heat affected zone High demands on appearance of the weld, visible weld Photo: Irepa

Main products at car body: roof seams, trunk lids, doors, C-pillars, water channels

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Laser Price & Beam Quality (joining) Laser Price Aluminium & Steel welding Brazing

Remote welding

8-12

25-40

60-150

Beam quality [mm mrad]

Beam quality should only be as good as required Laser Lines Ltd

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Laser Price & Beam Quality (joining) Laser Price Disc /Fiber Laser

Aluminium & Steel welding

∆ = 15 - 20 %

Diode Laser 30 mm mrad ∆ = 25 - 35 %

Diode Laser 100 mm mrad

Brazing

Remote welding

8-12

25-40

60-150

Beam quality [mm mrad]

Beam quality should only be as good as required Laser Lines Ltd

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Cladding and Coating : Principle

Powder and assist gas is fed into the laser beam coaxially or off-axis

Laser Beam

Laser Beam melts powder and eventually base material Alloying or depositing of powder onto base material in one or more layers

Powder nozzle and gas

Repair or coating in a single process Spot geometry adapted to parts and process

Cladding zone

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Cladding Installation with Diode Laser Cladding/Coating with Diode laser High precision thick deposits (0.5 – 4 mm) Cladding rates of 9kg/hour have been achieved with a 6kW laser Fully automated, industrial process Repair of valuable parts Wear protection Successful replacement of CO2 laser Applications Oil drilling – down hole tools Aerospace and maritime industries Foundries – pan scrapers Steel industry – conveyor rollers in steel mills Photo: Technogenia/Laser Cladding Technology Ltd Laser Lines Ltd

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Hardening: Typical Data Fiber-coupled or direct diode laser 1-6 kW Rectangular spot, may vary by applications First industrial installations in 1999 Pyrometer typically used for closed-loop process control Homogenized focus 24 x 8 mm

20 mm

Photo: Erlas

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Polymer Welding Transmission welding of thermoplastics Contour welding on robot for even huge 3d-parts Quasi-simultaneous welding Welding with base material strength Main products: sensor housing, tubes, flat parts, leak/gas-proof containers, head/tail lights of cars Special wavelengths possible. Eg. 14xx nm for welding of clear/clear acrylic

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Conclusion High electrical/optical efficiency of more than 40 percent Low investment and maintenance costs Outstanding reliability and robustness (up time > 99 %) Mobility and compactness Easy integration in systems for production. Ease of use and service Excellent beam quality L Low maintenance i t d design i (0 (0.5 5d day per year)) Excellent process stability and reproducibility

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Thank you for your attention Gary Broadhead Laser Lines Ltd [email protected]

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