How to improve the filling process of injection molded products?

(1) Improper adjustment of feed, shortage or excess.

Improper feed measurement or abnormal operation of the feed control system, injection molding machine or mold or operating conditions that result in abnormal injection molding cycles, low pre formed back pressure, or low particle density inside the material barrel may all cause material shortages. For particles with larger particles and larger voids, plastics with larger changes in crystallinity ratio, such as polyethylene, polypropylene, nylon, and plastics with higher viscosity, such as ABS, adjustments should be made when the material temperature is high, and the material dosage should be adjusted.

When there is too much material stored at the end of the cylinder, the screw will consume additional injection pressure during the injection process to compress and push the excess material stored inside the cylinder, greatly reducing the effective injection pressure for plastic to enter the mold cavity, making it difficult for the product to fill.

(2) The injection pressure is too low, the injection time is short, and the plunger or screw returns too early.

Molten plastics have high viscosity and poor flowability at low temperatures, so high-pressure and high-speed injection should be used. For example, when manufacturing ABS colored parts, the high temperature resistance of the colorant limits the heating temperature of the cylinder, and higher injection pressure and longer injection time should be used to compensate.

(3) The spraying speed is slow.

For products with complex shapes, large thickness variations, and long processing times, as well as high viscosity plastics such as ABS, injection speed is very important. When high-pressure injection cannot be used to fill the product, high-speed injection should be considered to overcome the problem of insufficient injection.

(4) The material temperature is too low.

The temperature at the rear end of the cylinder is relatively low, and the melt entering the mold cavity rises to a point where it is difficult to flow due to the cooling effect of the mold, which hinders the filling of the remote mold; The plastic with low temperature and high viscosity in the front of the cylinder is difficult to flow, which hinders the forward movement of the screw, resulting in sufficient pressure indicated by the pressure gauge, but the melt enters the mold cavity at low pressure and low speed

If the temperature of the nozzle is low and the contact time between the nozzle and the cold mold is long when fixing the feed, it may cause heat loss. It may also be due to insufficient heat or poor contact of the nozzle heating ring, causing low material temperature and blocking the feed channel of the mold; If the mold does not have a cold well, use a self-locking nozzle and use a subsequent feeding program to maintain the necessary temperature of the nozzle; If the nozzle is too cold when the machine first starts, sometimes a flame is used to heat the nozzle externally to accelerate the temperature rise of the nozzle.