Finite element analysis and die design of heading processes of magnesium alloy screws

This study is to develop related manufacturing technologies of LZ91 magnesium alloy M6 screws. Firstly, a warm heading process composed of three stages is proposed. The material flow pattern of the billet inside the die is analyzed using the finite element analyses. The effects of the friction factor, die speed and forming temperature on the heading load are discussed. The effects of the stroke at the first stage on the formability at the second stage are also discussed. Finally, warm heading experiments are conducted using a self-designed die set and a lubricant of MoS₂. The experimental values of heading load and product shapes and dimensions are compared with the simulation results to verify the validity of the finite element models and the proposed warm heading procedures.