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Plug Weld – Welding Process, Symbols, Advantages & Uses

Plug welding or rosette welding is the common type of welding in the automotive manufacturing industry. If you are a welder or have an interest in the welding field, you must have an understanding of all kinds of welding to stand out from all other welders in your space.

A plug weld is a kind of weld that joins two thinner metals with a hole in the Outer metal to make a strong weld. In this blog post, we will discuss the welding process, its advantages, and its disadvantages. So if you want to have a deep dive into it, keep reading on.

What Is a Plug Weld?

Plug weld or rosette weld is the type of welding in which two metal plates are fused via the holes in the upper metal. The metal plates are usually thinner and contain holes in the outer plate of the metal.

The weld is done by filling the holes in a circular manner that fuses both metal plates. It is most commonly done on plates that are damaged due to corrosion or vibration.

Plug weld and spot weld are almost similar but the difference comes in angle and space availability. If there’s not enough space to adjust the spot weld, welders prefer the plug weld. Plug weld is a fantastic alternative for the spot weld because it offers a stronger weld than the latter.

To have an understanding of how it works, let’s move to its working phenomenon.

Plug Welding Process

Let’s break the plug welding process into five simple steps to get a better understanding:

1. Workpiece Preparation

The first and most important step in every welding process is the preparation of the workpiece. You always must clean the metal piece to avoid any debris or dirt pieces interrupting your welding process.

2. Marking Out

After cleaning your workpiece, make sure to evenly mark it. This is usually done in the uppermost metal that is thicker than the other to evenly space the welding, in case of more than one weld.

3. Drilling

Once you are done with marking, drilling comes. Drilling is the process in which you’ll make holes in the workpiece for the plug weld. The holes are usually made in the uppermost metal piece as they are thicker. The hole will be larger in thick metal than the tinner one. However, the holes’ size varies with the metal piece’s thickness and nature.

4. Clamping

Clamping is the method by which the metal pieces are held in place without being misplaced. It is done to make the process easy by holding the workpiece.

5. Make the Weld

After you have done the steps above, make the weld. It is the final and last step in the plug weld. This is done by filling the hole with the filler metal in two different ways. You can either start with the edges of the hole slowly moving into the hole or directly into the hole.

In the earlier mode, the weld is spread onto the edges of the holes and then filled with the circle. This way, the metal below gets some time to come up to the temperature of the above metal which reduces the chances of any damage and makes the weld strong. While in the latter case, the hole is filled inside to see the flow of the weld and the penetration into the back plate.

Common Plug Welding Mistakes

Here are the common welding mistakes mentioned that you must avoid:

  • Making the holes larger than optimum.
  • Not cleaning or over-cleaning the metal plates.
  • Over burning the metal sheets.
  • Making the hole too thinner which results in burning.
  • Inexperienced welder trying to plug weld for the first time.

Plug Weld Symbols

Weld symbols are used by welders to know the different aspects of filling holes. These symbols are usually in the form of a rectangle with a diameter on the left side. You can get an idea about the diameter, amount, spacing, and location of the hole via these symbols.

They also help you get an idea of the angle, holes to be filled and any contouring needed. They are important to set the specifications for weld plugs.


Following are the advantages of the weld plug that make it different from other welds.

1. Speed

It is a fast-speed welding process that makes it more productive in less time frame.

 2. Strength

It offers more strength that makes it suitable for heavy-duty metals. This weld penetrates the workpiece to a great extent, making it the least unbreakable.

3. Versatility

This welding process can be done on different kinds of metals including aluminum, stainless steel, and steel. Its application on different metals makes it versatile.

4. Clean and Safe

The fact that the metal needs very little cleaning after completion makes it a very clean process. This weld produces very fewer heat fumes and smoke because of no more heating. It makes it a clean and safe process than many others.

5. Economical

This welding doesn’t require much electricity and materials to be used making it a cheap process.

6. Easy-to-Learn

This welding method isn’t intricate and can be learned easily.

7. Portable

The plug weld material is easy to have in difficult-to-reach places making it easily portable.


The disadvantages rise due to the improper working of an individual. However, the process itself doesn’t have any disadvantages.

Uses and Applications

Plug welding has a lot of Applications in daily life. Some of these are listed below:

  • It has vast applications in joining dissimilar metals (from joining rods into the pipes or installing exhaust pipes onto vehicles).
  • It has vast applications in the aerospace industry.
  • It is widely used in the automotive industry.
  • Plug weld is most often used as a substitute for the spot weld.
  • It is widely used in construction projects.
  • Plug weld has applications where the spaces are small and weld machines can’t corporate.


Plug weld is widely used in the present era as it has wide applications all over the areas. It has many advantages with very less disadvantages, making it more versatile. We have described the process and the applications in detail above. If you have still got some queries, comment below to let us answer them.

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