Conference: Photonics 4 intelligent processing, 19.06.2019, Geneva Confidential Addup property1

Study of copper melting by laser for

additive manufacturing processes

Guillaume NORDET1-2 ; Patrice PEYRE1 ; Cyril GORNY1 ; Albin EFFERNELLI2 ; Frederic COSTE1

1- Laboratoire PIMM, groupe LASER, 151 bd de l’hoîtal, 75013, Paris

2- AddUp, 5 Rue Bleue, Z.I. de Ladoux, 63118 Cébazat

@mail : guillaume.nordet@ensam.eu ; guillaume.nordet@addupsolutions.com

Conference: Photonics 4 intelligent processing, 19.06.2019, Geneva Confidential Addup property

AddUp

2

AddUp offers its customers complete industrial metal 3D printing solutions : (Machine design and production, Solutions

HSE, Customer assistance and advice)

AddUp is a 50/50 joint venture between Fives et Michelin

Established at Clermont-Ferrand in 2016

Conference: Photonics 4 intelligent processing, 19.06.2019, Geneva Confidential Addup property

Additive manufacturing : LBM process

3

Laser Beam Melting (LBM)

Selective Laser Melting (SLM)

https://www.empa.ch/web/coating-competence-center/selective-laser-melting

SLM process parameters Usual values on SLM printer

Laser emission wavelength Infrared :1030 µm

Focalisation diameter 70 – 100 µm

Laser power 400 – 1000 W

Scan Speed 1 – 10 m/s

Powder layer thickness 20 – 100 µm

Scan strategy

Powder composition Maranging steel – Titanium …

Final part density >99%

Conference: Photonics 4 intelligent processing, 19.06.2019, Geneva Confidential Addup property

Contents

4

LBM for

copper

Absorption of

LASER energy

Laser-mater

interaction

Green laser to

melt copper

Parameters

dependance

Conference: Photonics 4 intelligent processing, 19.06.2019, Geneva Confidential Addup property

Bibliographic results on the SLM of copper

5

Colopi M., & al, Procedia CIRP 74 (2018) 59–63, 2018

Ikeshoji T& al, The Minerals, Metals & Materials Society, 2017

➢ Colopi, 2018

• d = 78µm

• P = 1kW

• V =1 m/s

• Substrat : 316L Steel

• Max density: 97%

➢ Ikeshoji, 2017 :

• d = 100 µm

• P = 800 W

• V = 0.3 m/s

• Substrat : pur copper

• Max density : 97%

0

20

40

60

80

100

120

140

0 500 1000 1500 2000 2500 3000

Ther

mal

dif

fusi

vit

y (

mm

²/s

Température (K)

Copper

Inconel 718

• Low infrared absorption

• High thermal dffusivity K/(ρCp)

• Many projections of melting copper

Heider A & al, Proceedings of ICALEO, 2012

Welded copper line

SLM copper part

Mills K., “Recommended values of thermophysical properties for selected commercial alloys”, 2002

Cagran C., Diploma Thesis, 2000

Conference: Photonics 4 intelligent processing, 19.06.2019, Geneva Confidential Addup property

Laser energy absorption

6

LASER

Absorption

Heating

Reflection

Transmition

Material1 = 𝐴 + 𝑅 + 𝑇

For metal : T = 0

Abso

rpti

on r

ate

(A%

)

R. Fabbro et al., Icaleo, 2017

Laser energy absorption is lower for noble metal in IR mode

Usual SLM welding regime are near to the key-hole formation :

more energy is absorbed due to a laser trap

A%

E

Key-hole

formationLiquefaction

SLM area

Conference: Photonics 4 intelligent processing, 19.06.2019, Geneva Confidential Addup property

Measuring copper absorptivity

Laser used :

●Infrared laser (λ = 1030nm)

●Green laser (λ = 530nm)

Calculated absorptivity for a Cu bed powder

at λ = 1030nm (Gusarov, 2010) :

A= 38 %

7

Sample

Integrating

sphere

LASER

Photodiode

Sample

Photodiode

Incident

beam

Absorption rate increase for powder bed both

green and IR laser.

Conference: Photonics 4 intelligent processing, 19.06.2019, Geneva Confidential Addup property

Laser-mater interaction at infrared wavelength

Laser-mater interaction occurs mostly

on a liquid phase

LASER

Liquid area

Solidifiedcord

Powder bedDenudation

area

8

0,00

5,00

10,00

15,00

20,00

25,00

0 500 1000 1500 2000 2500 3000

Ab

sorp

tivit

y(%

)

Température (K)

Drude-Lorentz

Absorptivity function of temperature calculated about

a Drude-Lorentz model

200 µm

Record Rate : 6400 fps

Conference: Photonics 4 intelligent processing, 19.06.2019, Geneva Confidential Addup property

Copper fusion with a green laser

9

Experimental prototypeGreen laser : 500 W IPG

Laser head

Main consol

λ = 532 nm

Pmax = 500 W,

Ppick = 2500 W

Frequency : 150 MHz

Pulse duration : 1,6 ns

Duty Cycle = 24 %

Laser head

X-table

Cell for argon

Objective and

camera

Optical

focalisation

Conference: Photonics 4 intelligent processing, 19.06.2019, Geneva Confidential Addup property

Influence of gas shielding on copper welding

10

Weld

direction

Detrimental influence of an oxygen atmosphere :

↗ variation of the two welding modes

2 welding modes :

• Conduction → Low penetration mode

• Deep penetration → High penetration mode

With argon Without

argon

Conduction

Deep penetrationA

B

A B

Deep penetration Conduction

Conference: Photonics 4 intelligent processing, 19.06.2019, Geneva Confidential Addup property

Fusion weld of a copper powder bed

11

1 21 2

1

2

Without powder With powder

Conduction Deep penetrattion

More stable weld for deep penetraton mode on powder

Conference: Photonics 4 intelligent processing, 19.06.2019, Geneva Confidential Addup property

Conclusion

12

Green laser allows to create continuous

line and surface

Possible to build small parts with a green

laser in the experimental prototype

However, no industrial prototype

available with green laser

For copper, using an other wavelength to

improve absortivity is not sufficient to

optain stable penetration

Thanks

Thanks to all the people of PIMM laboratories and

AddUp for their helps and advices on the work

Work carried out as part of the Ambition FUI

project supported by BPI and Auvergne-Rhône-

Alpes and Ile-de-France region