Molding defects and anomalies are ultimately reflected in the quality of the injection molded product. The shortcomings of injection molding products can be divided into the following points:
(1) insufficient product injection;
(2) Product overflow;
(3) product dents and bubbles;
(4) The product has a seam;
(5) The product is brittle;
(6) plastic discoloration;
(7) The product has silver wire, markings and flow marks;
(8) The product is turbid at the gate;
(9) product warpage and shrinkage;
(10) The product size is not allowed;
(11) The product is pasted into the mold;
(12) Material paste flow path;
(13) The nozzle is flowing.
The reasons for this and the ways to overcome it are described below.
1. How to overcome the lack of product injection
Insufficient product injection is often due to the fact that the material has solidified before it has filled the cavity, and of course there are many other reasons.
(1) Equipment reasons:
1 hopper interrupted material;
2 The hopper neck is partially or completely blocked;
3 insufficient feed;
4 The feeding control system is not operating properly;
5 The plasticizing capacity of the injection molding machine is too small;
6 The injection cycle caused by the equipment is abnormal.
(2) Reasons for injection molding:
1 The injection pressure is too low;
2 the injection pressure loss during the injection cycle is too large;
3 The injection time is too short;
4 The total pressure of injection is too short;
5 The injection rate is too slow;
6 The flow in the cavity is interrupted;
7 filling rate is not equal;
8 The injection cycle caused by the operating conditions is abnormal.
(3) Temperature reasons:
1 increase the temperature of the barrel;
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 unit.
(4) Mold reasons
1 The flow path is too small;
2 The gate is too small;
3 nozzle hole is too small;
4 The gate location is unreasonable;
5 the number of gates is insufficient;
6 cold material is too small;
7 insufficient exhaust;
8 The injection cycle caused by the mold is abnormal;
(5) Material reason: material fluidity is too poor.
How to overcome the product flashover:
The overflow of the product is often caused by the defects of the mold. Other reasons are: the injection force is greater than the clamping force, the material temperature is too high, the exhaust gas is insufficient, the feeding is excessive, and the mold is stained with foreign matter.
