Resistance Welding
Overview
Resistance welding is a process that joins metals by applying pressure and passing current for a period of time through the metal area which is to be joined. The key advantage of this method is that no other materials are needed to create the joint. This process differs from fusion welding, where the material is melted and a filler material is added to form the joint.
History
The first resistance welding techniques were developed in the early 20th century. The process was initially used for making wire and metal sheet products, but its use quickly expanded to other areas of manufacturing due to its efficiency and cost-effectiveness.
Types of Resistance Welding
There are several types of resistance welding, including spot welding, seam welding, projection welding, and flash welding.
Spot Welding
Spot welding is a type of resistance welding used to weld various sheet metal products. The welding process involves applying pressure and heat to the area to be joined by means of two electrodes. The heat generated by the resistance to the flow of electric current melts the metal, and the pressure forms the joint.
Seam Welding
Seam welding, another type of resistance welding, differs from spot welding in that the electrodes are wheels rather than stationary tips. This allows for continuous, rather than point-to-point, welding, creating a leak-tight joint.
Projection Welding
Projection welding is a modification of spot welding. In this process, one or both of the parts to be joined are formed to contain a projection(s). The projection concentrates the welding current, permitting the weld to be made in a specific area.
Flash Welding
Flash welding is a type of resistance welding that does not use pressure until the weld is completed. The parts to be joined are clamped and brought together slowly. The contact resistance causes arcing and the formation of molten metal or “flash.”
Process
The process of resistance welding involves the application of both heat and pressure to the area to be joined. The heat is generated by passing an electric current through the workpiece. The amount of heat generated is proportional to the resistance of the workpiece to the electric current and the amount of current passing through it.
Applications
Resistance welding is widely used in the automotive industry for its speed and efficiency. It is also used in the aerospace industry, in the manufacture of products such as wire mesh, and in many other areas of manufacturing where metal products need to be joined.
Advantages and Disadvantages
Like any welding process, resistance welding has both advantages and disadvantages.
Advantages
Some of the advantages of resistance welding include its speed, efficiency, and the fact that it does not require any filler material. This makes it a cost-effective method for joining metals, particularly in high-volume production settings.
Disadvantages
One of the main disadvantages of resistance welding is that it can only be used on certain types of metals and for certain types of joints. It is also not suitable for use with very thin or very thick materials.
Safety Considerations
As with any industrial process, safety is a key concern in resistance welding. Operators must be properly trained and must wear appropriate protective equipment. In addition, the welding equipment must be properly maintained to ensure safe operation.
Future Developments
The future of resistance welding looks promising, with ongoing research and development aimed at improving the process and expanding its applications. This includes the development of new electrode materials and the use of advanced control systems to improve the quality and consistency of welds.