© Fraunhofer IWS

C. Leyens1,2, F. Brückner1, S. Nowotny1

1

Fraunhofer Institute for Material and Beam Technology (IWS), Dresden, Germany2

Dresden University of Technology, Germany

Latest Development Work on Induction Assisted Laser Cladding Processes

© Fraunhofer IWS

Outline

introduction

laser cladding and induction heating

industrial applications

summary and outlook

Induction assisted laser cladding

© Fraunhofer IWS

highest precision and lateral resolution ≥50 µm

near net shape material deposition in 2D and 3D

beneficial coating properties:

100% dense, adhesion strength

tensile strength

dynamic fatigue behavior, …

minor heat input, low distortion

Surface cladding

Repair

Direct Manufacturing

Laser Cladding & Build-Up Welding Performance & Applications

Laser cladding in manufacturing technology

limitations for large-area claddings,

large material build-up, simple and

economically priced applications

but:

high investment and direct operation costs,

low deposition rates, low productivity

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Energy distribution in laser cladding

laser source

optics

Energy distribution of a typical laser cladding process Part 1: beam delivery

in Watt

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Energy distribution in laser cladding

process

Energy distribution of a typical laser cladding process Part 2: process zone

radiation power after opticslaser source

optics

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Energy distribution in laser cladding

only a few percent of the radiation are used for the process reduction of required energy in the process zone lead to a strong reduction of laser power

Energy distribution of a typical laser cladding process Part 2: process zone

in Watt

1133

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Process improvements by additional heat sources

aim: increasing the Productivity and Efficiency by means of combined energy sources

additional heating of the substrate

influence on the process energy balance:

-

reduced cooling rate -

reduced energy losses

energy sources: -

pre-heating in a furnace-

second laser beam source-

plasma heat source- flame-

inductive

preheating

of

complete

substrate -

local inductive energy supply

additional heating of the coating material

sharing the process energy:

-

high-efficient energy supply to heat / melt the cladding material wire or powder

-

laser energy used for the localization of the cladding process

energy sources: -

induction -

electrical resistance -

autogenous

flame -

radiant heat

© Fraunhofer IWS

Process improvements by additional heat sources

aim: increasing the Productivity and Efficiency by means of combined energy sources

additional heating of the substrate beneficial

additional heating of the substrate

influence on the process energy balance:

-

reduced cooling rate -

reduced energy losses

energy sources: -

pre-heating in a furnace-

second laser beam source-

plasma heat source- flame-

induction

heating

highest losses of process energy into the substrate

© Fraunhofer IWS

Process improvements by additional heat sources

additional heating of the substrate

energy sources act on the surface of the substrate

energy sources with heat intrusion into the depth of the substrate

-

traditional heating by a flame-

second laser beam source

-

plasma heat source

-

pre-heating in a furnace-

inductive pre-heating of complete substrate

-

local inductive energy supply

rapid heating by directly coupled energy sources necessary for efficient processing

reduction of temperature gradients in all axes necessary 1

1

Brückner

et al., J. therm. spray tech., 2007, 16(3)

© Fraunhofer IWS

Process improvements by additional heat sources

reduction of temperature gradients in all axis necessary 1

rapid heating by directly coupled energy sources necessary for efficient processing

local and directly integrated inductive energy supply1

Brückner

et al., J. therm. spray tech., 2007, 16(3)

© Fraunhofer IWS

Induction assisted laser cladding

Principle of tailored temperature distributions

extended t8/5 cooling time

minor temperature gradients at 500 °C

compensation of heat conduction into work piece by inexpensive inductive energy

temperature profile at laser cladding without…

Cross section of a laser weld track

… and with additional heating:

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Hybrid cladding head

hybrid cladding head

with integrated inductive energy

supply

coaxial powder

delivery

specially shaped

inductors, based on simulations

compatible to lasers

up to 10 kW, preferably diode

lasers

High-performance cladding using the IWS COAXpowerline technology

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Hybrid cladding head

Inductor design

inductor design strongly dependent on

work piece geometry

process parameters

materials

computer calculated design of the inductors

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Process results –

brittle coating materials

Stellite 20 on AISI 1045

conventional

laser cladding

hardness

≈

60 HRC

laser cladding

with local simultaneous

inductive preheating

(up to 700 °C)

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Process results –

productivity and efficiency

laser cladded polished cross section

without induction

deposition rate: ≈2,4 kg/h

Fe-based coating material

laser cladding with local and simultaneous

inductive preheating up to approx. 600-700 °C

deposition rate with local preheating up to 600-700 °C: ≈4,8 kg/h

perpetuation of typical laser-related coating properties

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Increasing of deposition rate

increased cladding rate through

additional inductive heating

example: Stellite 21 onto Steel

laser

powerinduction

powerdeposition

rate

8 kW 0 6.3 kg/h

8 kW 12 kW 14.5 kg/h

Process results –

productivity and efficiency

© Fraunhofer IWS

Reduction of costs

reduced laser power through

additional inductive heating

example: Stellite 21 onto steel

laser

powerinduction

powerdeposition

rate

10 kW 0 8 kg/h

4 kW 12 kW 8 kg/h

Process results –

productivity and efficiency

© Fraunhofer IWS

Industrial applications for high-power laser cladding

experimental setup:

diode laser laser

spot ≈

6 mm

COAXpowerline cladding unit

laser power 4 kW

42C on steel

vs

= 1300 mm/min

powder mass rate 40 g/min without induction

powder efficiency ≈

95 %

doubled deposition rate with induction

cross section without induction: cross section with induction:

Coating of big engine components

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Industrial applications for high-power laser cladding

Repair of ship drives

large-area repair of ship drives: 6 kW diode laser and IWS COAX8 nozzle

current example representing a record in

long-run cladding

using IWS cladding technology:

-

propeller shaft of a passenger liner: 11 m length, 26 t weight.

-

deposition of 300 kg Stellite material in operation time of 100 hours.

-

meanwhile the ship is back at sea.

strong increase of deposition rate by induction assistance

deposition rates > 10 kg/hsource: Roussakis

S.A. Ship

Repairs

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Summary & Outlook

increased deposition rate under perpetuation of laser-typical coating quality, potentially up to 30 kg/h

high cladding rates even at lower laser power

e. g. 4 kW Laser + 12 kW induction = 8 kg/h Co-based Stellite 21

crack-free deposition of non-weldable materials

cost reduction by reduced investment costs,

reduced production time, and advanced product’s properties

corrosion protection of large cylindrical parts, e. g. off-shore applications

hardfacing

of tools for the oil and mining industries

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Contact:

Prof. Dr. Christoph

Leyens

Fraunhofer IWS

Winterbergstraße 28

01277 Dresden, Germany

Phone +49 351 83391-3242

Fax +49 351 83391-3478

E-Mail

christoph.leyens@iws.fraunhofer.de

www.iws.fraunhofer.de

Thank you for your attention!

Latest Development Work on Induction Assisted Laser Cladding Processes