Laser welding – an interdisciplinaryresearch subject

Alexander Kaplan

Head of Division and professor at theDivision of Manufacturing Systems

Engineering (Produktionsutveckling)Department TFM / LTU

Division of ManufacturingSystems Engineering

Teaching:Production Engineering

Research:Laser processing

Production-planning,

LEAN

Automati-sation

Manufacturing

Laserprocessing

Laser welding

Cuttingµ-processingSurf. treatm.

Others

Area LUPO Production/Organisation Area Materials Science

Research disciplinesaddressed by laser processing

Implementation: People, Psychology

Factory layout, Logistics

Laser systems, Sensors, Automation

Laser process: Thermodynamics, Fluid flowQuantum physics, OpticsMaterials science

Product properties: Material, Mechanics

LASERLaser Lab:1 Yb:Fiberlaser: 15 kW cw3 Nd:YAG laser: 3 kW cw, 250 W pw, 200 W Q-pw, FHG2 CO2 laser: 6 kW cw, 80 W pw (TEA, 4 J)1 Excimer laser: 308 nm

CyberLab (web-conference access):

Disc laser: 4 kW – at Oulu U (FIN)2 Nd:YAG laser: ESAB and Twente Udiv. Fiberlaser: D, FIN, UK, S, etc.

Our Ancillary Laser Equipment

Gantry and industrial robots, xy-stagesGalvanometer optics, fibre optics

MAG welding set (hybrid welding)Powder deliveryHigh speed imaging + illumination laserThermocamera (avd. experim. mekanik)Seam trackingBeam analyser Reflectance measuring (Mid Sweden U)etc.

Laser Materials ProcessingLaser -

- welding- surface treatment- micromachining- cutting- rapid prototyping

Current Welding Projects

DATLAS – observing weld quality defectsHYBRIGHT – hybrid weld propertiesLOST – UHSS lightweight constructionNORHYB – Nordic hybrid welding networkFiberTube – Fiber laser welding, cuttingFiller wire impact on hybrid welding (ESAB)High Tech decision making in SwedenCyberLab – Lab experiments by videoconferencing (EU)

FiberTube

Laser welding projects

Productdevelopment

Material

Joint type

Process

Production,System

Processmonitoring

Mechanicalproperties

HYBRIGHT DATLAS

LOST/KOST

ESAB-PhDLaserNova-PhDMS U-PhD

EU CyberLab

EU ISSEAEU LaserTool

NFR

Ind.contracts 35 companies12 academics6 LTU-divisions

Hybrid laser-arc welding

Remote laser welding

Laser soldering

of microelectronic

multilayers

Imaging of metal vapour

Imaging of the melt motion

Mathematical model: Simulation of the keyhole collapse

Keyhole (melt cavity) collapse

Quality monitoring sensors

Correlations:• Photodiode signal• Melt pool/vapour imaging• Welding defects

Signal: thermal emissions(melt surface, vapour flow)

Research example:Welding defectSensor signal detectionWeld evaluationMelt pool imagingImaging evaluationEmission modellingSensor analysis

Theory

0

0,5

1

1,5

2

2,5

3

1 2 3 4 5 6

Weld speed (m/min)

Wel

d d

imen

sio

n (

mm

)

Weld depthWeld width topWeld width interface

0

0,1

0,2

0,3

0,4

0,5

1 2 3 4 5 6Weld speed (m/min)

Dim

ensi

on

KH

(m

m)

0

1

2

3

4

5

Dim

ensi

on

MP

(m

m)

KH WidthKH LengthMP WidthMP Length

Root notches

Stress / fracture mechanics

TestingCharacterisationFEATheory

Laser weldingAn interdisciplinary process

TheEnd