Experimental evaluation method for determination of friction characteristics and performance of cold heading coatings

An experimental method was designed to evaluate wire coatings for the cold-heading process. Coatings are employed to increase material formability and to reduce wear on tooling. Typically, evaluation of frictional properties proves to be difficult because of problems instrumenting machine tooling and both the complexity and number of stages in the forming process. The proposed test is a cold extrusion process utilizing a selected trapped-forward extrusion die, where load versus stroke data is collected. Three different coating ratings are generated based upon maximum extrusion force, standard deviation of the force, and the characteristic shape of the extrusion curve. Coating performance interpretations for the curve characteristics are discussed.