The results of superimposed 20- and 20,000-cps tool vibration in deep drawing, ironing, and cold-forging are presented. Equipment and instrumentation are discussed. The importance of proper dynamic force measurement is emphasized. It was found that: (a) punch vibration resulted in only an apparent force reduction proportional to the workpiece stiffness and vibration amplitude; (b) die vibration caused a true forming force reduction either by changing the direction of friction force or by altering the state of stress; (c) material properties were not affected, although in cold-forging, with superimposed 20,000 cps punch vibration, an apparent force drop of up to 60 percent was achieved; (d) surface finish and deep drawability of the material, under certain conditions, were slightly improved. It is recommended to use superimposed tool vibration only in continuous forming operations, and then only if certain necessary conditions can be satisfied.

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