Abstract:

Shrinkage and warpage (S/W)affected by processing conditions were measured separately by an innovative measuring method based on a polypropylene box-shaped part.The single factor analysis of variance（ANOVA） was used to determine whether processing conditions, such as melt temperature and holding pressure had significant effects on S/W or not.Different laws of S/W affected by processing conditions were set out on confidence interval graphs.These results indicated that holding pressure was the most significant factor for shrinkage, but mold temperature for warpage.With changing processing conditions, S/W variations were summarized as follows:contrary effects, shrinkage decreased but warpage increased with increasing melt temperature and injection velocity. Shrinkage reduced monotonously and warpage varied as U shape curve with increasing holding pressure. Shrinkage and warpage varied in the same way with changing other conditions.These results could be used to help minimize shrinkage and warpage of injection molded parts.