Rheoforging of thin case for IT devices with optimal process parameters and new type die design

Abstract

The latest trend in the cell phone component industry to use aluminium and magnesium alloys has resulted in the advanced processing technologies. Semi-solid forming process that is advantageous for the mass production of thin parts with complex shapes have been of interest as a promising tool for near net-shape manufacturing. This study describes a semi-solid forming process for the development of a 1 mm-thick cell phone case by using the rheological material prepared by electromagnetic stirring equipment. Thus, a new type of die design for indirect rheoforging was proposed to efficiently control the primary α-Al phase particles in the thin part under rheological conditions. Their microstructure and mechanical properties were investigated and compared to parts produced without electromagnetic stirring. Those products fabricated by electromagnetic stirring had better mechanical properties and globular microstructures than those fabricated without electromagnetic stirring. Several processing parameters such as punch velocity (30 mm/s), punch pressure (75–250 MPa), stirring time (10 s), and solid fraction (0–20%) were used. The optimal condition that resulted in a defect-free component with the improved mechanical properties was explained and discussed.