COMPUTER MODELING OF THE ORIGIN OF DEFECTS IN CERAMIC INJECTION-MOLDING .4. RESIDUAL-STRESSES

Thermal stress profiles were calculated for injection-moulded flat discs of a zirconia-polystyrene suspension by considering the heat flow in, and elastic properties of, the suspension in the solid state. The calculated maximum tensile stress in the centre of the moulded discs could be used to predict the incidence of cracking in moulding experiments. The computer model allows the influence of material and machine parameters on residual stress profile to be explored for the simple case of an infinite flat plate. In particular, high tensile stresses are induced by low mould temperatures and high injection pressures.