Excessive weld indentation can cause rejected product. It is a condition that is specified is some quality plans, AWS D8.7 Recommended Practices for Automotive Weld Quality- Resistance Spot Welding. To reduce indentation one must reduce excessive forces and heat at the surface.
Weld schedules are available in the Resistance Welding Manual and AWS Standard C1.1 for many of the most frequently used materials. The information commonly provided is the proper electrode design, size and material. The weld force, weld time and weld current are also published. The minimum distance between welds is usually listed and the expected nugget or button size is shown. Tensile properties frequently are also published. Other sources are the Tuffaloy and CMW Catalogs.
A weld schedule is an instruction 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, rates and all other pertinent data related to a job. It also includes the information about the part itself including material, thickness, number of welds, weld locations, quality requirements, and precleaning. This information is stored and can be used to set up the job on it’s next run. It also can be used as a ground zero if parameters have changed and you want to go back to where you started.
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