Influence of molding variables on defect formation and mechanical strength of injection-molded ceramics

摘要

Defects such as voids and cracks were found in ceramic injection moldings when the molding variables were not properly tuned. A factorial experiment revealed that the formation of the macroscopic defects was related to the melt temperature of thefeed-stocks in the injection barrel. Using a melt temperature significantly higher than the evaporation-starting temperature of the type of lubricant used (e.g. stearic acid) presents a propensity to introduce voids. An improper selection of the moldingvariables such as the hold pressure, the injection speed, and metering stroke, was found to aggravate the molding integrity by the formation of cracks in addition to the voids. The cause for the occurrence of these macroscopic flaws in the ceramicinjection moldings are discussed.