Evaluation of the Formability of Plastic/Zn22Al/Plastic Sandwiched Structures by Gas Blowing

摘要

For the manufacturing of electromagnetic interference (EMI) shielding enclosures for portable 3C (computer, communication, and consumer electronics) products, a superplastic Zn22Al thin sheet is inserted in between plastic plates and formed by in-mold blowing with gas pressure. In order to evaluate the formability of a plastic/Zn22Al/plastic sandwiched structure, free bulging tests are conducted in the temperature range between 135 deg C and 200 deg C in an infrared furnance. The results show that the ABS/Zn22Al/ABS sandwiched structure can be free bulged at 150 deg C with 0.21 MPa of gas pressure at a forming rate similar to that of the monolithic Zn22Al sheet. The PC/Zn22Al/PC sandwiched structure cannot be effectively bulged until the forming temperature is raised to 185 deg C. The optimized forming condition for PC/Zn22Al/ABS is either at 150 deg C with a gas pressure of 0.35 MPa or at 165 deg C and a gas pressure setting of 0.21 MPa. Also, the thickness distributions for Zn22Al and a variety of plastic/Zn22Al/plastic specimens after free bulging at various temperatures with various gas pressures are placed in comparison in this study.