Effect of forming conditions on frictional characteristic in cold bulk forming process of copper alloy

• Published in: Tribology international 2021-03, Vol.155, p.106786, Article 106786
• Main Authors: Zhang, Da-Wei, Yang, Guang-Can, Zheng, Ze-Bang, Zhao, Sheng-Dun
• Format: Article
• Language: English
• Subjects: Bulk forming; Cold working; Copper; Copper alloy C5191; Copper base alloys; Frictional condition; Low speed; Lubricants; Lubricants & lubrication; Ring compression test; Tearing
• ISSN: 0301-679X; 1879-2464
• DOI: 10.1016/j.triboint.2020.106786

Effects of working speed (v) of die and lubricant on frictional characteristics of C5191 copper alloy during cold forming process are studied. The friction on contact surface is mainly caused by slight ploughing in small deformation and tearing after adhesion in large deformation, which translates at a critical deformation (deformation threshold (DT)). DT increases with increasing v. Lubricants have little effect on DT at 0.15 and 15 mm/s, but have a significant effect at 1.5 mm/s. Lubricating effect of oil and Molykote is equivalent at low v, especially before the DT, but has notable difference at high v. However, the ploughing action and tearing area by adhesive friction at high speed are smaller than those at low speed. [Display omitted] •Deformation threshold (DT) for transformations between two friction mechanisms.•DT increases with increasing loading speed, lubricants has a greater effect on DT at 1.5 mm/s.•Oil and MoS2 are equivalent at low speed, but present notable different at high speed.