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By means of the explicit dynamic finite element method, the relationship between the tool-workpiece interfacial slip and several cross wedge rolling (CWR) variables is investigated for a flat-wedge CWR process. After defining the components of interfacial slip and area reduction, an experimentally validated finite element model of CWR is introduced. This model is used to analyze a total of 189 distinct operating conditions by varying workpiece material (aluminum 1100, steel 1018 and brass C21000), forming velocity 0.4∼4.0 m/s, area reduction (25 percent, 40 percent and 55 percent) and forming angle (20 deg, 30 deg and 40 deg). The numerical results indicated that forming velocity was an important variable in determining the interfacial slip characteristics of the CWR process analyzed. Additionally, the area reduction and forming angle were found to have a significant influence on the interfacial slip under the conditions considered.

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A pin-on-disk tribometer was used to investigate the influence of several parameters on the sliding friction coefficient between hard and deformable surfaces. Pin (1045 tool steel) and disk (aluminum 1100) were utilized to simulate the interaction of a harder tool sliding relative to a softer deformable workpiece. Friction coefficient results were obtained at 561 distinct operating conditions by varying the ball diameter (3.18, 6.35, and 12.70 mm), lubricant (oil B, oil A, and grease), sliding speed (0.1∼0.8 m/s) and normal load (50∼1200 g). Several relationships which characterize the behavior of the friction coefficient as a function of the shear factor, τk, are established. the importance of these relationships, as related to stamping and forming processes, is discussed. [S0742-4787(00)01703-3]