The plastic injection parts stick to the molds, making it rather difficult for ejection.There are mainly following causes:
Reason For Difficult Ejection
*Too much injection materials
*Overhigh injection pressure, overlarge dwell pressure and overlong dwell time.
*Overhigh melt temperature
*Overlow or overhigh mold temperture.
2)Molds Design & Mold Processing
*Incorrect design of draft.
*Improper design of ejector unit, incorrect position of extrusion, oversmall ejection force, no air intake device for the core resulting in vacuum during ejection.
*Rough molding surface of cavity.