- Spot Welders
Welder Machine Manufacturers said that Spot welders are commonly used to both manufacture vehicles and repair them, and the basic mechanics are pretty simple. They work a little like a staple gun:
Two copper electrodes pinch down on layered sheets of metal
Electricity flows freely through the copper, but the steel or aluminum being welded resists that flow
The friction from the resistance heats up the metal
When it becomes molten, the two (or more) sheets fuse together
The spot welder keeps pinching the metal for a moment while it cools, leaving a solid nugget holding the pieces together
If you’ve ever seen the skeleton of a car, you’ve probably noticed the circular spots connecting the parts. That’s a spot weld. When collision techs replace a portion of the frame, they use this type of welder to attach the new piece. For a more detailed look at spot welders, see “Shop Basics: Auto Body Spot Welders.”
- Brazing/MIG Welders
The “hot glue gun” of welders, a MIG (also called Gas Metal Arc Welding [GMAW]) welder is used to fuse two pieces of metal that are butted up together – either flat or at an angle – to form a joint. With a MIG welder:
You clamp an electrode onto the metal you’re working with.
The machine feeds a wire steadily through the gun and onto the metal.
The wire serves as the second electrode, forming an electrical arc between the wire and the metal, creating a pool that fuses the pieces together.
What’s called a shielding gas is released through the gun as well. True to its name, this gas protects the weld from contamination.
Welding with a MIG welder is generally simple, with some practice, but a few things make it even easier to manage:
A lightweight gun: The welding machine controls the speed of the wire feed, but it’s up to the operator to control the speed of the gun. If you’re using one that’s light and not bulky, it makes the process a lot easier.
Push/pull torch: Especially when using a thinner wire to weld materials like aluminum, there’s a chance it could buckle as it’s being pushed out by the wire feeder on the machine. A push/pull torch adds a pulling force to create tension in the wire and reduce the chance of a buckling, welded mess.
A soft-start feature: This setting, available on welders like the MULTIMIG 522, feeds the wire more slowly at the beginning of a weld for a smoother start.
3. Stud Welders
Just what it sounds like, this type of welder fuses a stud onto a piece of metal. An arc forms between the metal and the stud, contained within the gun. The stud welder forces the stud onto the metal, the molten material cools and the bond is formed.
This type of welder is used for dent repair. You would add a stud to an indentation, pull it out to pop the dent out and then cut off the stud. To learn more about what features and specs to expect in a stud welder or MIG welder, see our blog on the topic.
All three welders are a common sight in a repair shop. Learning how they work and how to use them is essential when working in collision repair.