SPE 4602 TEKNOLOGI PEMBUATAN

LASER BEAM WELDING

PENSYARAH : DR AMIRMUDIN BIN UDIN PELAJAR : LOI FOO CHEONG

History of Laser Beam Welding 1917 Postulate of stimulated emission by Einstein 1950 Physical basics and realisation of a maser (Microwave Amplification

by Stimulated Emission of Radiation) by Townes, 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

Laser Beam Welding (EBW) Electron Beam Welding (EBW) is a welding process

which produces coalescence of metals with the heat obtained from a concentrated beam composed primarily of high- velocity electrons impinging upon the surface to be joined.

Heat is generated in the work piece as it is bombarded by a dense stream of high- velocity electrons. Virtually all of the kinetic energy of the electrons is transformed into heat upon impact.

Schematic Layout of Laser Beam Welding

Characteristics of Laser Beams Welding A high energy concentration in the focal point of the

electron beam. Welding in vacuum leads to a special purity of the welded

seam and to the minimization of weld defects. Automated welding in vacuum with electrically well

controllable welding parameters guarantees a high reproducibility of the weld quality.

The high power density of the electron beam allows working with very high welding speeds.

The high welding speeds and the favorable total efficiency allow high productivity with relatively low energy

Penetration Depths & Welding Speed

The Application Industry for Laser Beam

Source : H Schultz (2000). Laser Beam Welding. Abington Publishing

Industrial Application

Temperature During Laser Beam Welding

Weldding Defect Undercuts/Overlaps

Grain Growth A wide ∆T will exist between base metal and HAZ. Preheating and

cooling methods will affect the brittleness of the metal in this region Blowholes

Are cavities caused by gas entrapment during the solidification of the weld puddle. Prevented by proper weld technique (even temperature and speed)

Weldding Defect Inclusions

Impurities or foreign substances which are forced into the weld puddle during the welding process. Has the same effect as a crack. Prevented by proper technique/cleanliness.

Segregation Condition where some regions of the metal are enriched with an alloy

ingredient and others aren’t. Can be prevented by proper heat treatment and cooling.

Porosity The formation of tiny pinholes generated by atmospheric contamination.

Prevented by keeping a protective shield over the molten weld puddle.

Advantages of Laser Beam Welding

Disdvantages of Laser Beam Welding

Conclusion

Laser beam welding opens up many opportunities for designing and economically joining machine parts. Various

branches of industry, which use laser beam welding include electronics, automotive, and food processing.