Resistance Welding Basics

Resistance welding is used in small products assembling. These include heating elements, smoke detectors, batteries, air bag detonators and medical devices. This process can join metals that are similar or dissimilar. These include planum, aluminum, gold, stainless steel, and brass. In this type of welding, an electrical current passes through the parts that are being joined together. The welding heat emerges during the current resistance between the electrodes and the joining parts.

As the heating current stops, the parts are still held together by the electrodes while the molten metal solidifies. There is difficulty when using this welding method to join small metal parts together. There has to be precision in the control of current, time and force during the welding process while ensuring that the assembly is not overheated. The level of heat produced in resistance welding will depend on the provided resistance of the electrode. It also depends on the work piece thickness and the electrode tip area. Metal pieces are welded as the electric current is supplied and the application of uniform pressure at the weld joint. The metal pieces are put between two resistance electrodes while electric current is supplied to the electrodes.

There are different processes in resistance welding which include resistance projection welding, flash welding, electric fusion welding, resistance spot welding, upset welding, resistance seam welding and percussion welding.

In projection welding, projections are usually made on work pieces where welding is to be carried out. The metals melt at projections under the current and heat pressure. Electrode life is basically on electrode welding.

Resistance flash welding is where two metal nods are fused and heated to form a joint. Resistance flash welding is the resistance butt welding where two metal pieces are heated at their ends and a joint is produced.

Spot welding is used generally for sheet metal work, the spot that lies between two metal pieces are at a given distance is welded. The spot size depends largely on the shape of the electrode tip. One advantage of the spot welding process is that it is very simple to arrange. Cooling water is also provided to cool the electrode. Pressure application is either done manually or hydraulically and it is also possible to use automation in the welding process. Industries normally use a multi-spot welding process for mass production.

The seam welding is a series of continuous spot welds between two metal pieces. Seam welding uses electrode in form of a wheel which applies pressure on the two pieces of metals bean heated. This process is commonly used for joining tubes and pipes. The electric resistance welding is used for tube and pipe production which produces a forged weld. The forged weld is produced when heat and pressure is applied to the weld area.

There are different factors that affect heat production during resistance welding. Some of these are the application of electrode pressure, current density of weld and time of weld, contour of electrodes, the size of the metal pieces and the materials of electrodes.