Welding combines two pieces of metal, creating a solid bond. This makes welding an ideal technique for returning damaged vehicles to like-new condition. Welding is perfect for collision repair — suitable for cracked panels, damaged fenders, and rusted metal. Without welding, damaged vehicles would be impossible to restore to their original condition.
There are a few types of welding used in auto-body repair, such as MIG, TIG, and stick welding. Are you new to the world of welding? Below are some of the key of the differences. Think of this as a guide to help you choose the best method for your needs.
Let’s start with the most common welding methods. Then we'll move on to suggestions for successful auto-body repairs.
What type of welding is used for cars?
Metal Inert Gas (MIG) is a popular welding method. It uses a gas shield and filler material fed through a wire dispensed through the welder. MIG welding is fast, creates strong welds, and works on various metal thicknesses. Another perk is that it requires only one hand to apply the weld. Unsurprisingly, MIG welders are the most-used machines in the collision repair industry.
Tungsten Inert Gas (TIG) is a more advanced welding technique. This is because TIG welding requires two hands — one for adding the material and one for the welding nozzle. TIG welding began in the 1940s and used a non-consumable tungsten electrode. TIG welding is like MIG welding in using an electric arc. Still, TIG welding works best for aluminum and thin sheets of stainless steel. It'll continue to be a valuable skill as cars become lighter.
Stick welding (or Shielded Metal Arc Welding)
Stick welding is another arc welding method for auto-body repairs, because of its portability. Most auto-body professionals opt for MIG since it results in higher-quality welds with fewer mistakes. However, stick welding works well for heavier jobs, such as replacing a damaged frame piece to support the vehicle’s structure.
What are examples of welding applications in the automotive field?
Auto body sheet metal is thin, which can be tricky for welders used to working with thicker material. During a weld, the metal around the welded area shrinks as it cools. This often causes distortion and affects the shape of the metal. Since sheet metal is susceptible to warping, a great welder uses the right methods to mitigate it.
Replacing damaged panels is the preferred collision repair technique for modern cars. However, older vehicle bodies are generally welded during repair or restoration. Rust damage is common on vintage vehicles, usually on the lower edges of the panels. That's where water tends to collect. This repair is so common that aftermarket panels are manufactured for many popular older cars.
When replacement parts are, pro welders use their expertise to repair damaged originals. A good welder can even create custom parts! Here are four specific auto-body applications for welding.
- Exhaust systems. These systems are often mad of thin metal, and can be prone to corrosion and rust. Welding can be a method for repairing or replacing an exhaust system. Small leaks in an exhaust pipe can be welded instead of replacing the entire system.
- Frames and fenders. Auto shops use welding to fix collision damage and add extra support where none existed. Cars with bent frames from accidents are sometimes straightened by welding on new pieces.
- Wheels. Auto-body shops save time and money by welding damaged wheels instead of completely replacing them.
- After-market parts. Bumpers, fuel tanks, and radiators are parts that experienced welders can repair. Expert welders can even create after-market parts by employing various welding techniques.
Auto body welding tips
Welding can be dangerous, but any welder working in a body shop can reduce the risks. It's critical to always follow safe practices and wear personal protective equipment (PPE). Knowing how to weld like a professional is good for you and the shop.
Here are a few welding tips to enhance your safety and quality.
1. Wear all safety equipment
Safety must be your priority, so wear all safety gear when welding auto parts. An auto-darkening helmet, leather gloves, safety goggles, and steel-tipped boots should top your PPE list.
2. Put up welding curtains
A welding curtain is designed to lower the risk of injury to nearby workers by shielding them from welding arcs. Since these arcs produce a ton of heat, there's a risk of burn injuries to bystanders. Welding curtains also block UV light, protecting bystanders from a potential eye injury.
3. Use the right welder for the job
You'll improve safety and quality by choosing the correct tools for the job. Start by picking a welding machine that will give you the best results for the task.
Remember to perform regular safety checks on your welder to test the wiring voltage, emissions, leaks, and grounding. Advanced welders for TIG and MIG usually need more maintenance than stick welders. But at the end of the day, consistent safety checks should always be a priority.
Need to pick up the right welder for the job? Check the PrimeWeld website for reasonably-priced, high-quality welders for every application.
4. Invest in quality welding clamps
Welding clamps securely hold your workpiece in place, whether a fender or frame. You don’t want any auto-body part to tip over mid-weld, so investing in quality welding clamps is a smart choice.
5. Clean the metal surface
A clean surface is essential. A dirty one will leave your welds compromised by dirt, grease, or other contaminants. Use a stiff brush to remove any impurities before you start welding.
6. Use low-power settings
Because auto body sheet metal is thin, it’s possible to burn through it using a high-power setting. If you are burning through the metal, you're not moving the torch fast enough, or your welder is set too high. Move the torch more quickly, and reduce the amp setting of the welder. For instance, a thinner wire (0.30 instead of 0.35) will also help.
7. Pick a suitable filler material
Choose a filler metal that matches the mechanical properties of your material. The filler should be less thick than the sheet metal. For example, a thickness of 0.6 mm filler is an ideal choice for welding a thin metal sheet of 1 mm.
The correct filler reduces the chance of corrosion, cracking, and other welding issues.
8. Use a skip welding technique
Unevenly distributed heat distorts and warps sheet metal components. To limit distortion, try to spread the heat as evenly as possible. An intermittent or skip welding uses a series of short welds at key spots to secure the thin sheet metal. After letting the metal cool for a few minutes, a TIG welder can fill in the “skipped” areas.
9. Work with a small-diameter wire
Use the smallest diameter solid wire electrodes when MIG welding. You’ll have better control with the smaller wire. Smaller wires take less energy to melt, resulting in fewer issues with overheating. Auto-body welders recommend a 0.023” or 0.024” wire for a light gauge sheet metal or .030” heavier sheets such as 18-gauge.
10. Attach backing or chill bars
Keeping the heat-affected area touching a backing or chilled bar speeds up heat dissipation. Welders can strap an aluminum or copper bar to the workpiece for quick heat transfer.
11. Keep practicing
Welding is dangerous and can result in injury or death if improperly handled. When first learning to weld, taking time in every aspect of the welding process is essential. Start by examining your equipment, ensuring it is safe and ready.
Once correctly set up, MIG welding is clean, fast, and works well with thin metal sheets. It is the easiest welding process to learn and is commonly used for automotive bodywork. You will become proficient at patch and panel welding through trial and error. With enough practice, there is no limit to how well you can weld.
12. Take Your Time
Working for someone else might make you feel pressured to complete repairs quickly. However, rushing the welding process often results in inferior welds and accidents. Your well-being and the safety of those around you must always be your number one priority!