What is spot welding? Explaining the features, advantages and disadvantages

Welding plays an important role in processing metals, and the welding techniques and base materials used vary depending on the product.

Spot welding, one of the welding methods, produces a beautiful finish and is easy to perform, and is widely used in everything from cars and trains to personal DIY production.

This article provides information on what spot welding is, its differences from other welding methods, and its advantages and disadvantages for those in charge of manufacturing who are looking into basic information about spot welding and want to know its advantages and disadvantages. Let me introduce you to the disadvantages.

What is spot welding?

There are three types of welding: fusion welding, pressure welding, and brazing, and spot welding is a type of pressure welding.

▼Types and methods of welding

In spot welding, pressure is applied using electrodes from above and below the metals to be joined, and current is passed through the metals to melt the metals using the heat generated by the electrical resistance.

It is called spot welding because the welding area is small and the joint is made at a single point. It is also called resistance welding or resistance spot welding because it uses electrical resistance.

The welding time is relatively short and no specialized skills are required, so even beginners can easily perform the process.

The metals used in spot welding are diverse, including high-strength steel plates, mild steel, stainless steel and aluminum, which have high electrical and thermal conductivity.

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Differences from other welding methods

There are various welding methods, and they are used depending on the product and base material. Some methods are similar to spot welding, so it is important to understand the differences between them.

①Arc welding

Arc welding is a welding method that uses electrical discharge phenomena in the air to join metals, and is classified as fusion welding.

While spot welding uses heat generated by electrical resistance, arc welding uses arc discharge to melt the base metal.

Arc discharge can reach temperatures exceeding 20,000 degrees in some cases, making it possible to weld all kinds of metals.

Spot welding does not require any qualifications, but arc welding carries the risk of electric shock and explosion, so it is recommended that you take a course.

②Laser welding

Laser welding, which is classified as fusion welding, is a welding method that uses the heat of laser light to join metals. Laser light is powerful and easy to control, allowing for detailed welding.

In recent years, the development of fiber lasers that utilize optical fibers has made it possible to weld without causing distortion to the base material.

Additionally, laser welding requires a solubilizer during welding, so welding must be performed while irradiating inert gas to prevent the metal from oxidizing.

Types of spot welding machines

There are two types of spot welding machines: "stationary" and "portable", and there are small differences depending on the power source type.

Stationary types are characterized by size limitations, as the base metal is basically set in the welding machine.

Portable types are available in gun transformer and stational type, and the welding method is double-sided spot welding or prod welding (single-sided spot welding). Many of them are small, portable, and highly maneuverable, making them suitable for detailed work.

There are three types of power supplies: single-phase AC type, inverter DC type, and capacitor discharge type. The characteristics of each are as follows.

▼Types and characteristics of power supply formats

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Advantages and disadvantages of spot welding

Spot welding has both advantages and disadvantages, so it is important to understand both.

The main advantage is that the working time is short, leading to increased productivity.

▼Advantages of spot welding

• short welding time
• Less impact on base material
• Easy to handle even for beginners
• Fewer consumable parts (cost reduction)

On the other hand, disadvantages include metal thickness limitations and strength issues.

▼Disadvantages of spot welding

• There are limits to the thickness of metal that can be handled.
• Momentary high current may affect other electrical equipment.
• This may not be possible depending on the shape and size of the product.
• Power supply equipment may be expensive

summary

In this article, we explained the following about spot welding.

• Overview of spot welding
• Differences from other welding methods
• Types of spot welding machines
• Advantages and disadvantages of spot welding

Spot welding is a simple and safe welding method that even beginners can use.

In addition, because it has little effect on the base material and produces a beautiful finish, it is widely used in automobiles, trains, home appliances, etc.

​Daido Kogyo offers stational type, portable types, and spot welding machines for foundation rebar.

Industrial machinery professionals will listen to your company's concerns and provide consulting support to resolve issues.

You can check the list of welding equipment products here.

Thank you for reading to the end.

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