Spot Welding 101: Everything You Need to Know

Are you thinking about doing some DIY spot welding? There are a million reasons somebody may need to permanently join two pieces of metal, and spot welding may be the best way to do so.

It is especially common in the automotive industry during the original creation of the car's body and for cheap repair options, such as a broken exhaust pipe. The welder needs to understand the specific circular points for welding and other welding basics.

What Is Spot Welding?

Spot welding is a quick welding technique to join two materials, usually metal, without affecting the other areas of the material. The strategy uses copper alloy electrodes to weld two pieces together. Through a concentrated pressure and high heat, the two pieces are melted together and fused as they cool.

The pieces are typically referred to as workpieces, and they must be able to conduct electricity. Depending on the industry and need, spot welding is used for sheet metals, aluminum alloys, and even nickel straps that are used to join battery terminals.

Is it Dangerous?

Spot welding can be dangerous, particularly to welders who do not take basic safety precautions. Be sure the area to be welded is clean and easily accessible. Given the amount of heat and current, the materials need to be tightly secured.

Be sure your hands and eyes are protected from the intense light of the welding torch and have all your necessary equipment gathered before you start the job.

How Does Spot Welding Work?

Spot welding works by producing conductive heat. Conductive heat is created by electrical currents. The two workpieces are held together by copper alloy electrodes. Copper is known for high heat conductivity.

When the electricity flows through the copper alloy electrodes, concentrated heat melts the metal workpieces. The melted workpieces come together at the spot where the welding happens (thus the name spot welding), and fusion occurs between the two pieces.

As the workpieces fuse together, the electricity is no longer needed, but the copper alloy electrodes continue to be useful by applying pressure until the pieces are fully fused.

Spot Welding Materials

How Thick Should the Material Be?

Why Spot Weld?

What's the Difference between Them?

Spot welding is one type of resistance welding. Resistance welding relies on pressure and electrical current to pass through metal workpieces at the location they will be joined. It is a cost effective weld because no other materials are needed to form the bond.

Spot welding, along with seam welding, projection welding, flash welding, and upset welding are all types of resistance welding. The main difference between them is the type and shape of electrodes used to apply pressure.

Seam Welding

One resistance welding process is seam welding, which uses the same resistance welding method. Instead of a shaped electrode that stays in one spot, seam welding uses wheel-shaped electrodes. The metal moves through those electrodes, which roll along the seam to create joints between the sheets of metal.

Both use conductive heat created by electrical currents. Instead of using an electrode confined to one spot, seam welding uses wheel-style electrodes that that allow the metal to move over the course of a seam.

Projection Welding

Projection welding is a type of resistance welding that also uses conductive heat and resistance. Projection welding uses projections or intersections that focus heat generation at a specific point.

Once the current generates sufficient heat and pressure, the projections or intersections collapse forming a weld nugget. This is the process used in cross-wire welding.

Flash Welding

Flash welding, like all resistance welding, uses heat and current to fuse workpieces together. Resistance is generated through a flashing action by using high current at a small contact point between the workpieces.

Once the flashing has begun, force is applied to the workpieces, and they are pushed together and allowed to fuse.

Upset Welding

Through the use of heat and current, upset welding adds force to fuse two workpieces together. Unlike flash welding, upset welding begins with the two workpieces already touching each other so they are not moved and no flashing occurs.

Pressure is already applied to create firm contact between pieces and then the current is added.

Things You Didn't Know about Spot Welding

Welder wearing a full welding gear performing a spot welding

Image by skeeze from Pixabay

Beyond exhaust pipes, there are many practical uses for spot welding that many people never consider. For instance, spot welding can be an alternative to pop riveting.

Two items that can be joined by pop rivets often could be spot welded. In industries the spot welding alternative could save time, the cost of the rivets, and form an even stronger bond.




General Repair


Welder wearing a full welding gear id doing a spot welding

Image by Emir Krasnić from Pixabay

Hopefully this article has helped you understand spot welding better. Like all processes, it has advantages and disadvantages. If used properly and safely, spot welding can be a great tool for major industry as well as home repair buffs.

Spot welding can quickly and efficiently join two pieces of metal, but the skill of the welder and the limitation of the process may not be adequate for all purposes. The current has to be applied for the correct amount of time to make the fused joint as strong as possible.

It is difficult for some non-professional welders to properly place the electrode so they reach all necessary parts of the metal. The positioning of the electrodes will go a long way in determining the strength of the weld. If the current is not too weak, the heat insufficient, or the metal not held with enough force, the joint will suffer.

Nonetheless, the efficiency of spot welding makes it a popular choice, and if done well, it is strong enough to hold automobiles together. And while all welding has a level of danger, spot welding requires no open flame.

Shifting from man-powered spot welding to machine-powered, automated spot welding, hundreds of spot welds can be performed in just seconds.

Any time two pieces of metal are joined together, it is worth at least asking whether spot welding is an option. It can save you time and money, and help you get better at a skill that can come in handy for the rest of your life.

Featured Image by skeeze from Pixabay

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