Basics Of Resistance Welding

Knowing the basics of resistance welding is important to make welding more precise and flawless. Resistance welding is mostly used in the automotive industry. The precision welding required to weld on small items, especially nuts and bolts, is possible through resistance welding.

There are several types of resistance welding based on functionality and weld requirements. Gathering basic knowledge about each welding can help you apply the appropriate process.

This guide will discuss different types of resistance welding and how they work. Also, you will know the advantages and disadvantages of resistance welding. So, let’s start now!

What Is Resistance Welding?

Basics of Resistance welding
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Resistance welding is also known as Electric Resistance Welding (ERW). In this process, High pressure is created by driving a strong electric current through joint metals. As a result, joint metals melt and make welding joints strong.

How Does Resistance Welding Work?

The principle of resistance welding is to generate heat through electric resistance and melt the metal with that heat to form a joint. So, it works based on electric-powered pressure. How high heat will be created from electric flow depends on the time. The more time you flow the current, the more the heat will be. All types of resistance welding follow the same principle.

The formula for resistance welding heat generation is H = I2RT


  • ‘H’ =generated heat (the unit of heat is indicated by joules
  • I‘ = electric current (the unit of electric current is indicated by ampere)
  • R’= electric resistance (the unit of electric resistance is the ohm.)
  • T’=the time of current flow (the unit of time is seconds)

The high electric current results in finer edges of the joint metals and makes melting easier. The great convenience of this process is that you don’t require any flux, filler material or shielding gas.

Types Of Resistance Welding

Resistance welding is mainly divided into four categories. Let’s know in brief about these.

1. Spot Welding

It is considered the easiest resistance welding. Here, the workpieces must keep below the force of an anvil face. As a result, the workpieces come into contact with the electrode and run the electric flow. In the meantime, the workpieces will add some resistance to the electric current that reduces the extreme heat generation.

Note that the supplied current flow and dissolving time should be enough. When the current flow is stopped, the weld starts to get cold rapidly.

2. Seam Welding

The wheel-shaped electrode is required for seam welding. When the electric currents flow through the welding point, both electrode and workpieces melt by generated heat.

The workpieces must be inserted through the electrode current. A single spotted or completed weld may be created due to the overlap of defined intervals.

3. Butt Welding

Butt welding is used to join between thick metals or plates. In this process, the workpieces bind with the electrode using opposite force. When the workpieces get heated, there creates extreme pressure to produce nuggets. After this, at certain time intervals, the workpieces start melting and complete the welding.

4. Projection Welding

Projection welding is slightly similar to spot welding. Here, you can make a dimple at the preferred welding place. In this process, the workpieces should be placed among the electrodes and run huge current flow through the electrodes and workpieces.

Moreover, the welder can apply a little pressure on the shielding gas to spread the pressure through the electrodes. This pressure will allow it to melt the dimple and convert it into the preferred welds.

Advantages of Resistance Welding

  • All types of Resistance welding work on easier and similar principles. So, it is easier and requires no expertise.
  • It requires low voltage current that ensures users’ safety
  • It allows to weld on 20 mm thickness and 0.1 mm thinness
  • Welding speed is higher less than 1 sec
  • Resistance welding is environment-friendly because it produces less dust
  • This welding doesn’t require any filler metal, flux, and protective gases
  • It is possible to weld between a similar and a dissimilar metal

Disadvantages of Resistance Welding

  • Resistance welding is used for smaller and specific work pieces. So, you can’t apply resistance welding on larger or multiple workpieces.
  • Distortion or warping issues can occur in the finished project as the heat produced in resistance welding shrinks or expands at different rates.
  • Setting up the workpieces in perfect alignment is important to get strong weld output. Otherwise, resistance welding results may go wrong.
  • Resistance welding needs special equipment that can often be unavailable or expensive.
  • Resistance welding can be possible in some limited materials with high electric resistance.

Final Words

By the end of this guide, you have a thorough understanding of resistance welding. The welding done through electric resistance is known as resistance welding. This welding works based on the electric pressure created by the resistance that melts the workpieces to join them.

The core types of resistance e-welding are Spot, seam, butt and projection welding. We hope you benefitted from this basic resistance welding guide.

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