(1) feed shortage.
(2) the timing of refueling tube is not clean.
(1) gate is too small or too thin runner.
(2) the difference between the surface roughness of the cavity.
(3) Exhaust bad or mold temperature is too low.
(4) No cold well.
(1) uneven heating barrel, barrel temperature is too high or too low.
(2) pre-plastic backpressure nozzle is too small or too low.
(3) the injection speed is too large or too small.
(4) plasticized uneven.
(1) Not dried material.
(2) containing a volatile substance.
(3) The excessive amount of aid or release agent.
Stripping difficulties (gate or plastic parts tightening in the mold)
Equipment: ejection force is not enough.
(1) releasing structure is unreasonable or improper location.
(2) stripping slope is not enough.
(3) The mold temperature is too high or bad ventilation.
(4) runner cavity wall or surface roughness.
(5) the inlet nozzle and the mold match against posts or nozzle diameter greater than the diameter of the inlet.
(1) cylinder temperature is too high or too injection volume.
(2) injection pressure is too high or long dwell and cooling time.
Raw materials: lack of lubricant.
In the process of injection molding, there are still many problems. For example www.injectionmoldchina.com