Degradation of plastic from injection-molded parts and solutions

1. Injection molding machine

A. Excessive heating of plastic in the injection cylinder. 

Lower the melt temperature.

B. Temperature controller is not operating properly. 

Check that the temperature controller is in the correct area to control the injection cylinder.

Recalibrate the temperature controller and check for sticky contact, etc.

C. Incorrect thermocouple type is being used. 

Check that the thermocouple type used is the same as that provided on the temperature controller, such as FECON.

Check that all thermocouples are operating satisfactorily.

D. The plastic is being held in the injection cylinder for too long. 

Check the injection weight, if it is less than 25% of the injection pressure of the injection machine, turn the mold to a smaller injection machine.

If a smaller machine is not available, reduce the injection cylinder temperature to a minimum, which will produce a quality injection part.

E. Plastic stays in the injection cylinder when production is stopped. 

When stopping production, clean the injection cylinder so that the screw is in the most forward position.

F. Plastic is "stranded" somewhere in the injection cylinder and degrades. 

Look at the injection cylinder and remove any residue from the clamping surface.

2. Mold

A. The injection volume of the mold is too small. 

Move the mold to a smaller capacity injection molding machine.

3. Plastic

A. The moisture content in the plastic is too high. 

Use the correct drying sequence.

B. The quality of reuse material is different or contains impurities. 

Separate and strictly check the impurities in the reused material.