Shrinkage phenomenon refers to the phenomenon that the surface material at the wall thickness is pulled in due to the volume shrinkage of the product in the process of cooling and hardening, and thus the indentation marks appear on the surface of the product.
Shrinkage is usually associated with:
(1) injection process problems (such as injection pressure is too low, pressure holding time is not enough, mold temperature is too high, cooling time is not enough, etc.)
(2) structure design problems (glue level thickness is not uniform, the ratio of the width of the bar and glue level thickness is not appropriate, product glue level thickness is too thick, etc.)
(3) mold processing problems (feed mouth is too small or flow section is too small, etc.).