RELATIONSHIP BETWEEN SHORT-TERM TENSILE PROPERTIES AND PROCESS INTERACTION OF HIGH PERFORMANCE ENGINEERING PLASTIC

Abstract

THIS REPORT GIVES A BROAD AND INTEGRATED STRUCTURE OF HOW A PROCESS CONTROL TECHNIQUE IN INJECTION MOULDING OPERATION CAN BE DEVELOPED FOR A HIGH PERFORMANCE ENGINEERING PLASTIC, POLYSULFONE. THE IMPORTANT FEATURE OF THE TECHNIQUE IS THAT IT COULD KEEP ALL PROCESS VARIABLES CONSTANT WHILE ADJUSTING THE PARAMETERS UNDER INVESTIGATION. IN PARTICULAR, A PROCEDURE WHICH CAN PRODUCE PARTS WITH ALL PARAMETERS CONSTANT EXCEPT FOR THE MOULD AND THE MELT TEMPERATURES HAS BEEN DEVELOPED. THE EFFECTS OF THESE MELT AND MOULD TEMPERATURES ON THE SHORT-TERM YIELD AND CREEP PROPERTIES WERE STUDIED. THE ACTUAL CONTROL TECHNIQUE CONSISTED OF USE OF COMPUTER-AIDED-ENGINEERING SOFTWARE FOR MOULD DESIGN EVALUATION, CAVITY PRESSURE SYSTEM TO ENSURE CONSTANT CAVITY PRESSURE PROFILE, AND THE USE OF ENERGY METER TO MONITOR THE PROPER FUNCTION OF INJECTION MOULDING MACHINE. WITH THESE CONTROLS, IT WAS POSSIBLE TO PRODUCE PARTS WITH SPECIFIC MOULDING CONDITION CHARACTERISTICS. FROM THE DATA COLLECTED IN THE SHORT-TERM TENSILE YIELD STRENGTH TEST, A LINEAR RELATIONSHIP BETWEEN YIELD STRENGTH AND LOGARITHM OF STRAIN RATE WAS VERIFIED. DATA ALSO INDICATED THAT THERE WERE SOME SIGNIFICANT EFFECTS OF MOULD AND MELT TEMPERATURES ON THE GRADIENT OF THIS RELATIONSHIP. SIMILARLY. A LINEAR RELATIONSHIP BETWEEN APPLIED STRESS AND LOGARITHM OF TIME TO RUPTURE IN THE CREEP PERFORMANCE STUDY WAS ALSO VERIFIED. IN ADDITION. EXPERIMENTAL DATA COLLECTED INDICATED THAT THERE WERE SOME EFFECTS OF THE MOULD AND MELT TEMPERATURES ON THIS RELATIONSHIP.