Types of Resistance Welding Electrodes

Resistance welding refers to a method of using electric current through the workpiece and the resistance heat generated at the contact as a heat source to partly heat the workpiece. At the same time, the resistance welding machine will add pressure to the heating part. When welding, no filler metal is required. The productivity is high, and the deformation of the workpiece is small. Iit is easy to realize automation.

There are four main methods of resistance welding, namely spot welding, seam welding, projection welding and butt welding.

There are three key points of resistance welding. There are welding current, welding pressure and welding time. There is an important component in resistance welding that affects these three points- the electrode. Therefore, the electrode plays a very important role in the welding quality, and is responsible for the transmission of welding current, welding pressure and heat dissipation. Let us teach you how to choose electrodes.

Resistance welding electrodes must have the strength and hardness to withstand high temperature, because resistance welding generates a large amount of heat instantaneously when welding the workpiece. And the electrode must also withstand the high temperature of the workpiece to be welded. If the equipment wants to run longer, the essential requirement for electrodes is excellent resistance to deformation and wear.

As a medium for transmitting current, the electrode must have excellent electrical and thermal conductivity. Excellent electrical conductivity allows more complete transmission of current to the workpiece being welded, which allows for more precise current control. The resistance heating is small, and the heat from the welding area can be quickly dissipated, which increases the life of the electrode and improve the heating state of the surface of the workpiece.

The electrode requirements mentioned above are applicable to common carbon steel, stainless steel and other welded workpieces. However, when dealing with individual materials such as aluminum and aluminum alloys, it is necessary to choose electrode materials with low electrical conductivity, such as red copper, cadmium copper, etc.,

We offer copper, copper-based alloys, and refractory metals for resistance welding consumables, tools and accessories including electrodes, seam welding wheels, nuts and studs.

RWMA Class 1 – Copper-Zirconium and Copper-Cadmium: Electrodes for welding aluminum alloys, magnesium alloys, coated materials, brass and bronzes. Can be used for both spot and seam welding.

RWMA Class 2 – Copper-Chromium and Zirconium: These materials are stronger than Class 1 materials, have slightly lower conductivity. They are used for spot and seam welding of cold and hot rolled steel, stainless steel and low conductivity brass and bronze. They are also used as flash welding dies, and as electrodes for the welding of galvanized steel and other coated materials.

RWMA Class 3 – Copper-Nickel-Silicon-Chromium and Copper-Nickel-Beryllium: Their high hardness makes them ideal for electrodes for spot and seam welding of high resistance materials such as stainless steels, nichrome, inconel, and monel metal. As a casting, they are used for flash, butt and projection welding electrodes and fixtures. Other uses are welding gun components, seam welding bearing and other current carrying structural parts.

RWMA Class 4 – Copper-Beryllium:  Electrodes material for flash, upset-butt and projection welding applications where pressures are extremely high and wear is severe, but where heat is not excessive. They are used frequently in the form of inserts and facings. They may also be used for seam welding bushings.

RWMA Class 20 – Copper-Aluminum: Aluminum oxide has exceptional resistance to deformation when welding and it is highly recommended for weld caps when welding coated and galvanized steels. It allows a stable start-up and generally outlasts other cap material when welding parameters are not carefully controlled.

For refractory metals, we can offer tungsten, molybdenum, tungsten copper for electrodes.

Tungsten (W100) is very hard and has a very high melting point, so it is not easy to occur deformation under high temperature. Tungsten can also be machined based on customized drawings. Tungsten-made resistance welding electrodes can be used for cross-wire welding of metals such as copper and brass. It can also be used as inserted tips for brazing electrodes for upsetting operations.

Molybdenum is also very suitable for resistance welding electrodes for it has very high melting point and relatively high hardness. It can be used for welding or brazing of braided or solid copper conductors to ferrous or nonferrous terminals, lugs or fittings. And it is also used as inserted tips for brazing electrodes.

We also offer different grades of tungsten copper alloys in shapes of rods, cubes, plates, sheets and bars.

RWMA CLASS 10 – Tungsten 55% – Copper 45%: Suited for facings and inserts for projection welding electrodes and flash and butt welding electrodes. It is recommended where (relatively) high electrical conductivity and some degree of malleability is desired.

RWMA CLASS 11 – Tungsten 75% – Copper 25%: Suited to similar applications as Class 10, and for facing on electrode forming electrodes. It is harder than Class 10, and is for general use in projection welding electrodes.

RWMA CLASS 12 – Tungsten 80% – Copper 20%: Suited for electro-forming and electro-forging facings, and for electrode facings used to upset studs and rivets. A material for heavy-duty projection welding electrodes.

Except these grades, we also offer 60WCu, 70WCu, 85WCu.