Projection Welding

Questions and Answers

Class 11 material is a designation of the Resistance Welding Manufacturers Alliance (RWMA).  It describes a Tungsten/Copper base material with good conductivity and excellent strength at high temperatures and forces.  Class 11 is often used as a back up electrode for projection welding.

Class 3 material is a designation of the Resistance Welding Manufacturers Alliance (RWMA).  It describes a group of copper alloys with excellent strength and good electrical conductivity.  Class 3 is often used to weld stainless steel, nickel alloys and other highly resistive - strong materials that require high weld forces.

bar stock

Class 3 Bar Stock

Class 2 material is a designation of the Resistance Welding Manufacturers Alliance (RWMA).  This is a group of copper alloys with high strength and electrical conductivity.  Class 2 is the most used material in the resistance welding industry.  As electrodes it is used for welding bare and coated steels.

bar stock

Class 2 Bar Stock

The proper electrode material can be determined from published weld schedules based on the work pieces being spot welded. These weld schedules can be found in AWS Standard C1.1, Recommended Practices For Resistance Welding and RWMA The Resistance Welding Manual. Your electrode supplier is another source. Spot welding requires a few initial decisions to be made to set up a good welding process. Most of these evolve around pressure, current and time.

Cooling is possibly the most important factor in electrode life. Proper water tube location will insure water flow as close as possible to the working face with the proper flow and temperature water. In each resistance welding application after the weld schedule is determined and the proper pressure, current and time (PCT) are set another important factor for electrode life is water cooling. Even with the proper setting every electrode will see very high temperatures and forces on its face. Over time this creates the traditional mushrooming of the weld face. To slow this face wear down we must reduce the time at high temperature that the weld face sees. Proper water cooling of the electrode is critical.

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