The Reason Of The Defect Of Plastic Injection Molding And Its Remedy(2)

- Oct 30, 2017 -

The reason of the defect of plastic injection molding and its remedy(2)

Dimensions of injection molded parts are different


1. Characteristics of defect of injection molding

The change of weight in the injection molding process exceeds the production capacity of mould, injection molding machine and plastic combination.


2. Possible causes of problems

(1). The plastic in the cylinder is not uniform.

(2). The range of temperature or fluctuation of the ejection cylinder is too large.

(3). The capacity of injection molding machine is too small.

(4). The injection pressure is unstable.

(5) screw reset instability.

(6) change of operating time and consistency of solution viscosity.

(7). Injection speed (flow control) is unstable.

(8). Use of plastic varieties that are not suitable for mold.

(9) consider the influence of mold temperature, injection pressure, speed, time and pressure on products.


3. Remedies

(1). Check for adequate cooling water flowing through the hopper throat to keep the right temperature.

(2) check whether the thermocouple is inferior or loose.

(3). Check whether the thermocouple used with the temperature controller is the correct type.

(4). Check the injection molding and plasticizing capacity of the injection molding machine, then with the actual injection amount and the injection per hour

Compare the amount of plastic used.

(5). Check whether there is a steady melt heat in each operation.

(6) check the backflow prevention valve for leakage and replace it if necessary.

(7). Check for incorrect feeding Settings.

(8). Ensure that the screw rod is stable at every operation, i.e., no more than 0.4mm.

(9) check the inconsistencies of operation time.

(10). Use back pressure.

(11). Check whether the hydraulic system is functioning properly and the oil temperature is too high or too low (25-60oc).

(12). Select plastic varieties suitable for mold (mainly from shrinkage and mechanical strength).

(13). Rearrange the entire production process