A New Method for Evaluating Friction in Coining Process of Rib–Groove Component: Local Constraint Extrusion Test of T-Shaped Component

A friction test named the local constraint extrusion test (LCET) of a T-shaped component was designed to reflect the geometric characteristics of the rib–groove components such as bipolar plates in solid oxide fuel cells, and the deformation characteristics during its coining process. The geometric parameters of the die and the initial geometric parameters of the sample for the friction test were determined by the projection of the rib height for the ternary systems. A calibration process for the friction condition based on the LCET was developed. Friction tests were conducted for the cold coining process of 441 stainless steel with molybdenum disulfide grease, and the results indicated that the friction condition was m = 0.252, where the error between the experimental results and the calibration curve is less than 0.5%. When the friction calibration curves and test tooling are sufficiently improved, the developed LCET can also be used for the friction evaluation of warm, hot, or energy field-assisted coining processes of rib–groove components.