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Causes of surface scarring of plastic products

Update:13-05-2020
Summary:

The term explains the linear trajectory of the surface […]

The term explains the linear trajectory of the surface of the molded article, which shows the direction of melt flow. Two fault analysis and troubleshooting methods The flow of molten material causes the surface of the plastic part to have an annual ring shape centered on the gate. Wavy traces. The temperature of the mold and the nozzle can be increased separately, the injection rate and filling speed can be increased, and the injection pressure, holding pressure and pressurization time can be increased.China Plastic Pallet Moulds Suppliers
A heater can also be provided at the gate to increase the local temperature of the gate portion. It is also possible to appropriately increase the area of ​​the gate and runner, and the cross section of the gate and runner is preferably circular, so that the best filling can be achieved. However, if the gate is placed in a weak area of ​​a plastic part, a square cross-section should be used.

In addition, the bottom of the inlet and the end of the flow channel should be provided with a large cold hole. The influence of material temperature on melt flow properties is more important. Pay more attention to the size of the cold holes, and the location of the cold holes must be set in the melt. The end of the flow direction is along the injection port. The molten material in the flow channel does not flow smoothly, forming spiral wave flow marks on the surface of the plastic part.

 

When the melt flows from the narrow cross-section of the flow path into the cavity with a larger cross-section, or when the flow path of the mold is narrow and the finish is poor, the flow may form turbulent flow, thereby forming a wavy flow on the surface of the spiral plastic part. In this regard, the injection speed can be reduced appropriately, or the injection speed can be controlled slowly, quickly and slowly. The gate of the mold should be placed in the thick wall or directly on the side of the wall. The gate form is preferably a shank, fan or diaphragm. The cross section of the runner and gate can also be increased appropriately to reduce the flow resistance.

Volatile gases form a cloud-like flow mark on the surface of plastic parts. When using ABS or other copolymerized resin raw materials, if the processing temperature is high, the volatile gas generated by the resin and the lubricant may form a cloud-like wave flow mark on the surface of the plastic part. In this regard, the temperature of the mold and the barrel should be appropriately reduced, the exhaust conditions of the mold should be improved, the material temperature and the filling rate should be reduced, and the gate cross section should be appropriately increased. The type of lubricant should be changed or the amount of lubricant should be reduced.