Resistance Spot Welder Guide
What is a Resistance Spot Welder?
Resistance spot welder, also known as resistance spot welding machine, is designed for welding multiple metal sheets together. Welding refers to the process of joining and fabricating the metals or other materials like thermoplastics together. Most welding methods need to be performed at a high temperature, melting the materials and then cooling down the welded parts. There are also other metal fabrication methods that can process at room temperature, which eliminate the melting process of the base materials, for example, friction welding, brazing, soldering and so on. Common energy sources of a variety of welding methods include but are not limited to electrical, chemical, frictions, lasers, ultrasounds, electron beams, electric arcs.
Resistance spot welder can join two or more metal sheets together through heating and applying pressure on the welding point. Resistance spot welding is a kind of electric resistance welding. In a resistance spot welder, the heat is generated from the resistance to electric currents. The contacting electrodes work on the surfaces of metals where the electric current and pressure are applied onto, then the heat will generate through resistive metal materials, for example, low carbon steels.
Resistance spot welding machines are widely used in industrial production of automotive and aerospace components, rail industry, metal furniture, electronics, medical building and other industries. Resistance spot welding is one of the most conventional metal welding processes. With the development and combination with automatic operating systems or robots, resistance spot welding machines are popular for metal joining in mass production lines and especially preferred in the automotive industry for over a century.
How Do Resistance Spot Welders Work?
In a resistance spot welding machine, several metal sheets can be welded together without using any filler material. Resistance spot welding utilizes alloy copper electrodes to transfer the currents through work pieces in the welding area. Subsequently, the metals melt due to the generated heat while the energy is concentrated to a small welding point under pressure. Applying a large current to the point will efficiently melt the sheets in the resistance spot welder to form the weld. The work pieces can be fused together when the currents are turned off and the electrode pressure maintains on the point. As the molten metals solidify and cool down, the joint and the permanent connection of metal sheets are formed.
Copper is the typical electrode because it has ideal heat conductivity and lower electrical resistance. The heat therefore tends to generate in the metal sheets rather than the copper electrodes. The amount of energy that is conveyed to the welding area is determined by the current, the magnitude and the resistance between (different types of) electrodes, the materials’ properties and thickness. Generally, the thickness of the materials, the metal sheets, is ranged from 0.5 to 3mm. If the energy is not enough to melt the metal materials, it will end up a poor weld.
On the other hand, if delivering too much energy, the heat will melt too much material and make a hole on the surface eventually. Resistance spot welding machine can regulate the energy which is going to transfer to produce effective welds. Another feature of the welder is that it can deliver a large amount of energy in a short process time, which is about 10 milliseconds. This allows the resistance spot welding machine to perform metal joining without excessive heating of other areas on the surface.
Application and Materials
Resistance spot welding machines are commonly used when welding metal sheets, wire mesh or welded wire mesh. Thicker materials are more difficult to weld since the heat affects the surrounding metal significantly. The thermal conductivity and electrical conductivity of the materials are also important factors when selecting appropriate welding materials. For example, aluminum alloys have high thermal conductivity and therefore need larger welding currents to perform resistance spot welding. Also, in this case, it requires more powerful transformers which is bigger and more expensive. Steel, which has considerably lower thermal conductivity and also higher electrical resistance, is much more suitable to be resistance spot welded. Particularly, low carbon steel is most ideal welding materials.
Today, the most common applications of resistance spot welding machines are in the automotive production lines. The welders are used to weld the metals and form steel cars. Resistance spot welders can also be combined with automated control systems. In fact, many robots found on assembly lines nowadays are resistance spot welders.
Another typical application of resistance spot welder is welding and producing batteries. Resistance spot welders fuse thin nickel straps with the battery terminals. In the welding process, the welding machine can prevent the products from getting too hot, which is a strong advantage over conventional soldering.
Need help searching for your next Resistance Spot Welder ?
IMTS Exhibition includes manufacturers from around the world. Send us a message with your requirements and our IMTS Experts will happily help you with your questions.