Welding 101: What to know, where to begin
In today’s world of advanced vehicle repair, welding can play a central role. Yet, with many welding methods available, which one is “right?”
It is no secret that vehicle makers and the industries that supply the materials that make up the fleet on the streets strive to build safer vehicles. The quest drives the automakers and their suppliers to continually research and develop newer, stronger materials—and other materials—and determine the required joining methods for each location in a vehicle structure.
Steel and aluminum are the predominant metals used in body and frame construction of different vehicles. Each alloy or metallurgy comprises its own unique properties designed to perform in that vehicle’s structure to provide “as built” integrity. As such, there are unique considerations for collision repair, particularly in avoiding any adverse effects on future crashworthiness and occupant protection attributes of each vehicle repaired. No stronger, no weaker.
This continued evolution of vehicles comes with the need for the most up to date repair attachment methods. Receding in the rear-view mirror are the gas flame welding techniques when it comes to collision repair. By definition, welding is the joining of metals or thermoplastics through the introduction of heat to the melting point to join parts. Fusion welding uses similar filler material to the base materials being joined, whereas non-fusion welding such as brazing uses a filler material different from the base, with more of an adhesive process.
Here is a brief look at some common methods available in our industry today:
- Gas metal arc (GMA) has been a collision repair mainstay for the past four decades. It uses a wire feeder to deliver electrode filler wire to a gun handle assembly where the operator directs the deposition of the weld puddle to the join area. An electric current (arc) generates the necessary heat to melt the filler wire, and in the case of fusion welding, the metals being joined. This method is highly productive; however, it introduces high temperatures in the immediate weld zone; this can affect the properties of the materials being joined. GMA welding is highly dependent on operator knowledge and skill to set up the welder, tune, or program it for the material stack in the joint, and to execute the necessary weld.
- MIG brazing is a non-fusion GMA process which introduces an electrode filler wire that is commonly silicone bronze, producing an adhesive joint. The benefit of this process is that lower temperatures are introduced into the joint, which helps preserve the strength properties of ultra-high strength steels common in today’s vehicles.
- Tungsten inert gas (TIG) welding is an electric arc process whereby the operator holds a torch handle that houses a tungsten electrode (varying specific unique compositions dependent on the materials being joined). The tungsten electrode is used to direct the arc to the weld area while a shielding gas is dispersed to the area and the operator introduces the required filler rod by hand. This process is not common in mainstream collision repair. That being said, however, it is common in industrial fabrication, performance, and racing, and may be recommended in some exotic and high-end specialty vehicle repairs.
- Squeeze-type resistance spot welding (STRSW) is the primary joining method used by most vehicle makers on the assembly line. Sealers or adhesives may be used in the panel stack as well. Modern STRSW equipment is available to the collision repair industry and very capable of reproducing that factory look while minimizing the detrimental effects of the high heat input compared to the GMA welding.
Original equipment manufacturer requirements
Vehicle makers may require specific equipment to participate in their certified networks and may provide more than one option. Welding recommendations and requirements vary widely across the original equipment manufacturers (OEMs)—one size does not fit all. For instance, STRSW is the preferred or required method for many OEMs, while weld bonding is specified in some procedures, and other variations in the process may be required. Keep in mind as well that OEMs may identify other attachment alternatives such as rivet bonding.
To learn more about the basics of welding, and to know the different methods available, sign up for welding courses at I-CAR Canada.
About I-CAR Canada
I-CAR is an international organization dedicated to providing the information required to perform complete, safe, and quality auto repairs.
I-CAR Canada is a training and recognition program run by the Automotive Industries Association of Canada (AIA Canada), a not-for-profit organization representing, supporting and leading innovation in Canada’s $37.8 billion auto care sector.
Aimed at up-skilling tradespeople in the collision industry, I-CAR training has been available in Canada since 1979 and has been operated by AIA Canada since 2010.