Friction Tests in Magnesium Tube Hydroforming at Elevated Temperatures

In metal forming, lubricants have a variety of functions. The top priority is usually reduction of friction in order to increase the formability of the materials and reduce tool wear. Because magnesium alloys have very poor formability at room temperature, it is essential to manufacture a part from Magnesium alloys at elevated temperatures. The aim of this paper is to present a friction test method to evaluate the performance of different kinds of lubricants and determine their coefficients of friction at elevated temperatures in tube hydroforming of magnesium alloys. A self-designed experimental apparatus is used to carry out the experiments of friction tests. The coefficient of friction between the tube and die at guiding zone is determined. The effects of the internal pressure, the axial feeding velocity and temperatures on the friction forces and coefficients of friction for different lubricants are discussed.