Projection Welding
Questions and Answers
Some resistance welding applications call out forces above the limits of tapered electrodes. The RWMA Manual Fig 18.3 shows force vs taper. It shows that above 2400 Lbs force tapers are not viable. Above this force specially designed High Pressure/High Force Electrodes must be used. These electrodes can be straight shanks, threaded or flanged electrodes. They are available from several manufacturers. Contact your electrode supplier for assistance.
Reference: RWMA Resistance Welding Manual 4th Edition
Force is used for two main reasons. One is to contain the weld nugget and prevent expulsion and the other is to strengthen the weld by forging the solidifying weld nugget. It is easy to see that if welding force is changed these actions will be affected to some degree. Expulsion could increase or decrease and the resultant weld strength could also increase or decrease.
A weld schedule is an instruction of how to set up a resistance welder for a specific job. It includes all of the specific settings of the machine, control settings, tools, electrodes, forces, times, and rates and all other pertinent data related to a job. This information is stored and used to set the job up the next time you run it. It can be used as a ground zero if parameters have changed and you want to go back to where you started.
Group B materials is a designation of the Resistance Welding Manufacturers Alliance (RWMA). It describes a group of Tungsten/Copper materials with high strength and good electrical conductivity. Their main feature is high strength at high temperatures. Their properties make them excellent materials to use in the resistance welding industry as electrodes at high heat and forces.
Group A material is a designation of the Resistance Welding Manufacturers Alliance (RWMA). It describes a group of copper alloys with high strength and high electrical conductivity. Their properties make them excellent materials to use in the resistance welding industry as electrodes and current carrying componenets used in the machinery of the resistance welding industry.
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