An Overview of 05 Different Types of Resistance Welding

What is Resistance Welding? (Resistance welding basics)

It is a way of joining metallic materials without having to use any bonding material, unlike other methods of joining metals. Also, you do not need to create holes between the two metals because resistance welding works by the application of pressure on the two joining metals.

Therefore, it is unique, and the differences between it and other ways of bonding metals are apparent. Methods such as riveting and bolting cannot work if you do not create holes. Or, you should at least have some bonding materials such as a metal adhesive for it to work.

There are four processes involved in resistance welding. They include spot welding, projection welding, seam welding, and butt welding. Mostly, this method of welding is applicable in the automobile assembly industry.

Types of resistance welding

As mentioned earlier, resistance welding is one of the best methods metal workers can join material. They do this by heating the joining parts to the melting point using heat and pressure. That causes the two joints to merge and form a permanent bond once they cool down.

There are different types of resistance welding. The difference lies in the kind of work you are doing and the equipment that is at your disposal. Let us look into each of these types.

Resistance spot welding-RSW

In spot welding, there is the use of electrodes in the bonding procedure. Mostly, spot welding is ideal for joining two metal sheets to create a strong bond. For instance, it has been applicable in the manufacture of metal cans, car assemblies, and aircraft assembly.

How does it work?

So, how does it work? Well, as mentioned earlier, you need a pair of electrodes to achieve a durable bond. You begin by holding the metal sheets you intend to join in an overlapping position. Electrodes should be between two joining layers with one fixed and another mobile.

Spot welding is quick and can help you bond metal surfaces easily. It requires a current of 5000 amperes or more. Also, remember that you need 2 volts between the electrodes and 12 volts in the open circuit.

Pros and cons of spot welding

Spot welding is one of the least complicated ways you can bond two metal sheets. Also, you do not need much labor, equipment, or initial capital to use spot welding. Besides, it is the perfect way to weld to metals if you need a quick bond.

Also, there are downsides to using spot welding. Bonds created using this method require regular maintenance, and that calls for the use of skilled labor, which can be costly. Also, it works perfectly for less thick materials.

Resistance seam welding-RSEW

Seam welding requires a machine to do the job, but still, there is a need for human welders to oversee the process. It also uses electrodes to weld the seam that is existing between any two metallic surfaces that you would like to join.

How does it work?

The electrodes in this type of resistance welding are wheel-shaped. These are perfect for creating continual welds between surfaces and thus creating a strong bond. As already mentioned, it is good to use a machine for this type of welding.

Pros and cons of seam welding

As mentioned earlier, the wheel-shaped electrodes allow you to create multiple joints with less overlap. Also, the joints formed here do not allow gas or liquid to escape.

However, it is one of the most expensive ways of bonding metal materials, and you can only use it to join pieces of less than 3mm thickness.

Projection welding-PW

Projection welding is the most appropriate way of welding in the automotive and electrical fields. Like other methods, you need electrodes to achieve a strong and durable bond with this type of resistance welding.

How does it work?

As said, you need electrodes to achieve a projection welding bond. Apply the electrodes directly to the joining surfaces and use opposing forces through them. That will cause them to join, creating a strong bond.

For projection welding, you may need a current of between 4 and 20 volts. Also, it is advisable to use a three-phase machine for projection welding. Although it may be expensive, it has better power compared to other methods.

Pros and cons of projection welding

Projection welding allows you to place the welded surfaces firmly without any challenges. Also, you can weld more than one spot at a go, giving you more flexibility. It also results in neater bonded surfaces than other types of resistance welding.

Flash welding-FW

Flash welding is the most common type of resistance welding. Here, you do not apply too much pressure on the surfaces you are welding. You only need to apply light pressure and use heavy current. Pass the current through the surfaces, and that will make a bond between them.

How does it work?

Mainly, the bond in flash welding gets created from the heat applied through them. The pressure applied while heating endures the surfaces stick together.

Flash welding requires a current of around 12500 and 15500 A/C. Also, the voltage ranges between 2 to 20 volts depending on the thickness of the materials.

Pros and cons of flash welding

Flash welding is one of the fastest ways you can bond two surfaces. Since it requires less pressure, it is also less costly compared to other methods of bonding metals. However, you need to be careful because of sparks resulting from the procedure, which can be a fire risk.

Upset welding-UW

In upset welding, the bond does not get created in small spots. It is the whole surfaces coming together to create a strong bond. Also, the current that you pass through the two surfaces is what creates the resistance that leads to a joint.

How does it work?

Here, you need the pressure to work simultaneously with the current. You bring the surfaces together under pressure then heat the points at which you intend to join them. That is enough to create a strong bond between the two.

Upset welding is unique because it produces coalescence simultaneously during the bonding process. Therefore, a bond results from the current that goes through this surfaces.

Pros and cons of upset welding

It results in a clean bonded surface, unlike some other types of resistance bonding. However, it is ideal for some level of thickness and may not work correctly on all metal sizes.

FAQs

  • What is The Advantages of Resistance welding?

There is three advantage of resistance welding. All advantage are:

  • It is environmentally friendly
  • It is quick
  • It forms durable joints
  • Arc welding vs. Resistance welding

Resistance welding uses an internal heat source to bond surfaces while arc welding uses an external heat source.

  • What kind of shielding is necessary when doing resistance welding?

You need a safety glass or a fire-resistant plastic shield.

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