LASER WELDING - Literature Review

Lasers are now being used in the automotive industry to produce seam or stitch welds, as alternatives to conventional resistance spot welding, which are used extensively for attaching auto-body panels to subassemblies. The advantages of laser welding over resistance spot welding result from the smallness of the laser spot size, the large penetration depth of the weld into the material and the requirement that only singlesided access to the workpiece is necessary. Further, the equipment used to carry out the welds can be easily adapted to new vehicle program changes, unlike that used for resistance spot welding. Potential benefits realised by the application of laser welding include reduced flange widths, increased structural strength and high speed automated processing. Traditionally CO2 lasers have been used for auto body applications. Recent advances have been made with Nd:YAG lasers, which are now capable of producing beam powers of more than 2 kW or more through a fibre optic cable. This is particularly useful for robotic operations, where it is necessary to manipulate the laser beam about a stationary part. Lasers are also used in the manufacture of tailored blanks, where suitably prepared sheet metal, including differing thickness and material combinations, are butt welded together prior to being pressed into the finished shape. This results in considerable cost and weight savings and increases structural rigidity.