Process-Induced Effects in Compression Molding of Ultra-High Molecular Weight Polyethylene (UHMWPE)

摘要

Manufacturing of high quality compression-molded parts requires a thorough understanding of the effect of processing conditions on the quality of the final part. The effect of eight different processing variables on the quality of compression-molded patella buttons was investigated using a design of experiments approach based on Taguchi methods. The quality of the patella buttons was characterized using density, crystallinity, tensile strength, tensile modulus, and optical microscopy for microstructure. Tension testing was carried out on microtomed films and was found to be sensitive to the consolidation of the powder. The tension testing was used to reveal the effect of processing on tensile modulus and tensile streength. Density was affected the least by the variations in processing conditions, crystallinity and Young's modulus were moderately affected, while tensile yield strength was affected the most. Among the different processing variables, soak time at melt, cooling rate from melt, and the pressure applied during the processing cycle caused the maximum changes in the crystal-linity, strength, and stiffness of the part. The presence of incompletely fused flakes in the poorly consolidated parts led to a viscous behavior of films with a low crystallinity and modulus. However, well-consolidated parts had a high crystallinity and modulus.