Projection welding and spot welding are resistance welding of two types. Both are in wide use for the different industries in which calls for the fusing of embossed or projection joints. What then is the differentiator. For now, in this article, we shall focus on projection welding alone.
The Principle Of Working
Resistance Projection Welding (RAW), is popularly known as projection welding. The basic principle is that the joining of two metal sections that are to set in position between two electrodes. With the exertion of high pressure on these electrodes, the system is put through to the passage of current. The internal resistance of the plates generates heat formation. The emphasis here is that the heat generation is a result of internal resistance and not any arcing effect. The projections focus this heat. As the electrode pressure increase, the projection begins to disintegrate, so forming a high quality fused nugget. So this then is briefly the operating process of projection welding.
The choice of the projection requires careful thought. Typical projections in use are conical, spherical, and button type. All, however, exhibit the cardinal requirement of focusing the heat to and so forming the weld. There is a correlation between projection type and plate thickness with button type in use for greater plate thicknesses.
Projection welding takes precedence over a lot of other welding techniques owing to the doing away with time constraints. Multiple joints are done simultaneously with this technique. So if you need to complete multiple welds, your answer is here. No wonder many manufacturers tend to lean towards this form of welding.
Another critical hinge-point of this expertise is the prolongation of electrode life. You kill two birds with one stone- the lesser need for replacing electrodes and the curtailment of costs. But why is that? In projection welding, weld formation is a blend of the outcome of heat and force applied. The supplied current leaves the electrodes unaffected. It requires very little current and thereby the life of an electrode is much enhanced.
At times, unwanted plating material may remain on the plates capable of crack formation. This method removes the material resulting in a top-class weld.
Advantages And Disadvantages
- Minimal electricity usage so it requires less amount of current
- Prolonged life of electrodes
- Can handle almost all thicknesses of metal
- Use possible to weld joints in inaccessible and complicated locations
- Because heat balance is an important aspect of welding science and this form of welding achieves a good balance
- Not useable with some types of copper and brass
- Formations of projections are challenging and so requires personnel of high skills
- Application to all workpieces has a limit because, among the considerations, the composition of the metal has to be taken into account.
The Future Of Projection Welding
It is in the picture that Resistance Projection Welding is expanding its applications base because of the endeavor to weld newer, harder metals. Related welding equipment is undergoing improvement, so introducing newer heads, better electrodes, power supplies and what have you. Research on a new series is ongoing into using two electrodes on one side instead of the customary one. Market growth is burgeoning over the globe, but how long before the competition gets into the act?