Molding shortcomings and anomalies are finally reflected in the quality of injection molded products.The disadvantages of injection molded products can be divided into the following points: (1) insufficient product injection; (2) product overflow; (3) product dents and bubbles; (4) product has joint marks; (5) product is brittle; (6) Plastic discoloration; (7) The product has silver threads, markings and flow marks; (8) The product gate is turbid; (9) The product warps and shrinks; (10) The product size is not accurate; (11) The product is pasted in the mold; (12) Material sticking to the runner; (13) Nozzle drooling.
The following describes the causes and solutions to overcome them one by one.
⒈How to overcome insufficient product injection Insufficient product injection is often due to the fact that the material has solidified before the cavity is filled, and of course there are many other reasons.
⑴ Equipment reason: ① The material hopper is interrupted; ② The neck of the hopper is partially or completely blocked; ③ Insufficient feeding amount; ④ The feeding control system is not operating normally; ⑤ The plasticizing capacity of the injection press is too small; ⑥ Abnormal injection cycle caused by equipment.
⑵ Reasons for injection molding conditions: ① The injection pressure is too low; ② The injection pressure loss is too large during the injection cycle; ③ The injection time is too short; ④ The total injection time is too short; ⑤ The injection rate is too slow; ⑥ The material flow in the cavity is interrupted; ⑦ Varying rate of mold filling; ⑧ Abnormal injection cycle caused by operating conditions.
⑶Causes of temperature: ① Increase the temperature of the barrel; ② Increase the nozzle temperature; ③ Check millivoltmeter, thermocouple, resistance heating coil (or far infrared heating device) and heating system; ④ Increase mold temperature; ⑤ Check the mold temperature control device.
⑷ Mould reason ① The flow channel is too small; ② The gate is too small; ③ The nozzle hole is too small; ④ The gate location is unreasonable; ⑤ Insufficient number of gates; ⑥ The cold material hole is too small; ⑦ Insufficient exhaust; ⑧ Abnormal injection cycle caused by mold;
⑸Material reason: material fluidity is too poor.
⒉How to overcome product flash and flash: Product flash is often caused by mold defects. Other reasons include: injection force is greater than clamping force, material temperature is too high, insufficient exhaust, excessive feeding, foreign matter on the mold, etc.
Post time: Sep-01-2021