Today we are going to discuss solutions and precautions for common problems of hot runner molds

1. Aperture at the gate

Cause: The temperature around the gate is too high
Solution: Change the nozzle temperature and / or the temperature of the gate cooling water channel to achieve the best temperature. For PC, the temperature of the gate area is preferably between 110-130 degrees, for PMMA 90- 110 degrees is better;
Checking during the mold test: measure the actual temperature around the gate and adjust it in time to ensure stable production;

2. Obvious gate marks on the surface of the product
Reasons: the valve needle is too short, the gate temperature is too low, the holding pressure is too large, or the time is too long, the injection time is too long;
Solution: Checking the length of the valve needle and the coordination with the bell mouth; check the distance between the nozzle core and the mold; increase the temperature of the nozzle, and (or) optimize the temperature of the cooling water channel; If the dimensions are qualified, reduce the pressure value and time of holding pressure;.

3. Little flash around the gate.
Cause: The cone surface of the valve needle and the mold cavity are not well matched;  and the temperature in the gate area is too low;
Solution: Checking whether the connection between the valve needle and the mold seat is connect correct. and check whether the distance between the nozzle core and the mold is proper. Control the input air pressure of the cylinder. Increase the nozzle temperature or optimize the cooling water temperature.

4. A lot of burrs around the gate

Cause: The temperature in the gate area is low and the holding pressure is too high;
Solution: Increase the temperature in the gate area, reduce the holding pressure, and check the distance between the nozzle core and the mold.