Pvc injection molding transparent surface brightness is different, that is, the production of gas (gas marks): in the injection molding process, before the injection of glue, the cavity is all air, when the plastic material is injected into the cavity, the air is oppressed Run out, and as the amount of glue increases, the air volume becomes smaller and smaller, which is why the air is forced to start to flow out. When the exhaust design is unreasonable or the injection speed and pressure are too fast, the faster the exhaust speed, and the bad exhaust gas, the air pressure will increase, resulting in local high pressure and high temperature, making the product surface bright. The gas pattern occurs mostly at the rubber inlet, which is because the gas flows out from here and causes a high temperature to appear in the air. If it is inside the mold, it is whitish (bright) or burnt. If it is the glue inlet, it can be judged as gas mark, but the USB head structure is very small, it is impossible to have such a situation - the gas volume is too small; and on the surface, it should be trapped, causing light , so it looks like there is also a color difference.
Injection molding of PVC, especially for injection molding of rigid transparent PVC, it is necessary to pay attention to the following points.
One: Hard transparent PVC has higher requirements on thermal stability and higher flow performance requirements.
Second: the glue inlet of the mold should be enlarged compared to other plastics, and the exhaust gas should remain unblocked.
Three: Before the raw materials are used, they need to be treated with baking materials. Generally, the baking materials are about 68 degrees for three hours.
Four: The formulation system of PVC pellets should be reasonable.
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