A multi-step lubricant evaluation strategy for wire drawing–extrusion–cold heading sequence

The upsetting-sliding test was used to simulate the characteristic contact conditions of a cold heading sequence comprising two operations, wire drawing and direct extrusion. Friction conditions for each elementary forging operation were analysed according to the lubrication parameters, such as ageing of the soaping phosphate line, immersion time in the phosphating bath, and additional lubricants (drawing powder and cold heading oil). The results enabled: (i) better knowledge and control of the changing friction conditions as the forging procedures progress; (ii) predicting and remedying lubrication damage, and (iii) anticipating the geometric variations of the forged product according to the friction conditions.