Most injection-molded parts would bore holes for the purpose of assembling with other parts. Holes are often made by punching rather than injection molding to prevent formation of weld lines at the vicinity of the hole. As there is a possibility that punching could lead to deformation and cracking in the parts, the appearance around the punched hole in injection molded glass-fiber-reinforced polyphenylene sulfide (QF/PPS) plate was observed in this study. The punching speed and testing temperature (temperature at which punching was done) were varied. The plastic deformation distance, which could be observed at the vicinity of the hole, increased with increasing testing temperature and decreased with the increase of punching speed. The deformation area at the surface of the hole had slightly increased above 125°C and this was not affected by the punching speed. Furthermore, crack formation at the vicinity of the hole was evident. Cracks increased with increasing punching speed and decreased with increasing testing temperature. Since the punching temperature and speed have opposite effects on hole deformation, these parameters can be controlled to minimize the occurrence of cracks. However, total impediment of deformation and cracks is not quite possible.
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