Solutions to defects in injection molding processing
The shortcomings and anomalies of injection molding 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 inaccurate; (11) The product is pasted in the mold (12) Material sticking to the runner; (13) Nozzle drooling. The following describes the causes and methods 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 Reasons for equipment: ① The hopper is interrupted; ② The neck of the hopper is partially or completely blocked; ③ The feeding amount is not enough; ④ The feeding control system is not operating normally; ⑤ The plasticizing capacity of the injection press is too small; ⑥ The injection cycle caused by the equipment is abnormal. ⑵Causes of injection molding conditions: ①The injection pressure is too low; ②The injection pressure loss during the injection cycle is too large; ③The injection time is too short; ④The injection total pressure time is too short; ⑤The injection rate is too slow; ⑥The material flow in the cavity is interrupted ⑦ The mold filling rate is not equal; ⑧ The injection cycle is abnormal due to the operating conditions. ⑶ Temperature reasons: ① Increase the barrel temperature; ② Increase the nozzle temperature; ③ Check the millivoltmeter, thermocouple, resistance heating coil (or far infrared heating device) and heating system; ④ Increase the mold temperature; ⑤ Check the mold temperature control device. ⑷Causes of injection moulds: ① The runner is too small; ② The gate is too small; ③ The nozzle hole is too small; ④ The gate position is unreasonable; ⑤ The number of gates is insufficient; ⑥ The cold slug hole is too small; ⑦ Insufficient exhaust; ⑧ Injection mold The injection cycle caused by abnormal; ⑸Material reason: the 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.