Spots mainly refer to the smears with fog or bright color near the gate of the part or the curved scars from the gate that resemble the squeaky scars attached to the gate. They are caused by plastic forwards entering the cavity or by excessive pressure retention. The cold material that was squeezed into the cavity later caused.
The front material is cooled due to the cooling effect of the nozzle or runner. It is cooled and solidified before it enters the cavity. When it enters the cavity and expands and enters the cavity, it forms a melt fracture, followed by later heat. The molten material pushes and it becomes a cold spot.
Solution:
1. The cold material well should be set well. Also consider the form, size and location on the gate, to prevent the cooling rate of the material from disparity.
2. The centrality of the nozzle should be adjusted well. The fitting size of the nozzle and the mold should be designed to prevent leakage or cause cold material to be carried into the cavity.
3. The mold has a good degree of exhaust. The gas interference will make the gate appear cloudy markings.
4. Increase the mold temperature. Slow down the injection speed, increase the injection pressure, reduce the packing pressure and injection time, and reduce the packing pressure.
5. Dry the plastic. Use less lubricant to prevent the powder from being contaminated.