The production of small, high precision components requires an extremely localised welding technique. Laser welding has been developed to provide small cross section welds with very low heat inputs. This paper outlines the mechanisms of laser welding and supports this discussion with industrial examples. The first example is the production of hermetic seals by overlapping pulse welding. The second example involves the joining of a small cobalt based torsion spring to a stainless steel substrate by simultaneous spot welding from three directions using optical fibres. The final example demonstrated is not a true welding technique as the join involves a minimal amount of mixing of the two metals involved. In this case a satisfactory joint is produced between a Tungsten alloy and a Cobalt-Iron alloy, which have widely different melting points, by “braze welding”. A braze weld is produced by locally melting the lower melting point component and wetting the higher melting point substrate with this melt. In this way a thin diffusion bonded layer is generated.
By reference to these three different techniques it is demonstrated that laser welding is a powerful and versatile tool capable of producing welds which are not possible by traditional techniques. The thermocapillary or Marangoni flow effects and the mixing of the different elements has also been studied using Backscattered Electron Imaging of the weld cross section.