What welding trends do you see in the automotive industry?

In the automotive industry, we have moved away from using the term welding (fusion) to the term joining as putting a vehicle together involves various methods that may or may not fit within the welding term. By far, automotive is still using resistance spot welding as the most common joining method. The equipment for this form of welding is fairly cheap and can be robotic or manual; however, as technology has advanced in joining techniques there are many more options available. As we focus on the continual requirement of reducing emissions and meeting CAFE standards the Body-In-White (BIW) portion (vehicle structure including frame if it has one) must continue to find ways to get lighter while still meeting crash standards. Not that long ago it seemed that Aluminum was going to be the best way to achieve this, however, advances in steels from advanced to ultra-high-strength and now Gen 3 steels have allowed steel to still be a viable material for BIW structures. In the past we used the term Light-Weighting when looking at the BIW structure, however, that term has now been replaced with Right-Weighting where we are mixing materials in order to get the right mix of weight and strength for every part of a vehicle. This has led us to differing categories of joining.

The below image is an attempt to capture these in a simple way. We have conventional welding or fusion methods that are used like spot welding, as already mentioned, and gas metal arc welding. Other areas of fusion welding include laser, plasma, and adding fasteners either through projection or drawn arc methods. All of these are methods for fusing parts of similar material type-together. When wanting to join dissimilar materials other methods such as mechanical or what I call hybrid joining are required. Mechanical joining methods include processes such as Bolting, Flow Drill Screwing, Self-Piercing Riveting, Clinching, and Hemming. These processes sometimes require an added element to the assembly that also adds weight to the overall vehicle, but all use some type of method to lock one part to the other without the need to add a noticeable amount of heat. For hybrid joining, fusion welding of steel is used in conjunction with a steel element that can capture a different material type in between it and the steel component. The fusion joining method can either be through resistance welding or friction welding. Finally, when looking to join parts a solid-state method of joining can be used through Friction Stir welding. This is a process that heats materials up to their plastic state through a rotating tool and then the materials are mixed along a seam or in single point locations and this creates the joint. While typically used to join similar materials, this method can also be used to join dissimilar materials, though sometimes a substrate is required in between the joining parts to limit any negative impacts of the mixing of the materials.

automotive welding diagram

Automotive joining is a vast area of methods and technologies where one can continue to learn with each new project or allows for a lot of research as we continue to push the limits of what we can use to construct vehicles.

Ian Cross, P.Eng., LSO Chief Engineer, Joining Valiant Machine & Tool Inc.