The GMAW and resistance spot welding processes are the most widely used methods of joining automobile body panels and structures in auto body repair shops.
Low-Current Gas Metal Arc Welding (GMAW)
Low-current GMAW is a logical choice for auto body repair work. Using the short-circuiting arc, the whole range of metal gauges commonly worked on in auto body repair can be handled by one small-diameter wire size. Low heat input results in minimal distortion, and welding often can be performed in close proximity to glass, trim and upholstery. The equipment produces consistent high-quality results, and can be used in many ways to reduce time for a job.
For example, the time savings which result from eliminating the need to remove trim, upholstery, floor coverings and other items are enormous. The low heat input also enables large areas of thin metals to be welded without distortion, thus eliminating the need for costly panel beating, bending and stretching. Parts which would normally have to be removed for resistance spot welding can be welded in place because gas metal arc welding machines are capable of welding in any position, and from one side only for either spot or seam welding. Another advantage is that GMAW machines can be changed from seam welding to spot welding at the flick of a switch.
Gas metal arc spot welding is particularly suited to body shop work because access is needed only to one side of the work, and there is no need to clean the back side of the metal. A further advantage over resistance welding is that fit-up is not nearly as critical, because gas metal arc spot and seam welding can be used to bridge fairly large gaps. These features offer considerable savings in many applications. See GAS METAL ARC WELDING and RESISTANCE SPOT WELDING.