First of all, the most common cause of uneven cable insulation is the stability of the raw materials. For example, the uneven mixing of the components of the cross-linked polyethylene material will cause the insulating material to be extruded at high temperature through the extruder. , forming a bulge in the insulating layer, and finally showing a bumpy appearance. In addition, it is caused by improper storage of materials, and the weak storage environment is high temperature and humidity, so some moisture will enter the material, and eventually the insulating surface will not be smooth.
Another major reason for the unevenness of the cable insulation is the phenomenon of raw rubber. The cross-linked insulated wire core sometimes has a raw rubber phenomenon during the production process, and the reason for this phenomenon is that the temperature of the machine neck or head is not enough, resulting in internal Local cold glue is produced, or local plasticization is not good due to insufficient body temperature or shear force. Another situation is that when the gasket of the filter screen is not in place, the extrusion pressure of the cross-linked insulating material is finally affected. , it will also produce raw glue, making the surface of the insulated core appear bumpy hard lumps.
There is also a phenomenon called the old glue phenomenon, which is caused by the excessive temperature of the head when the cross-linked material is extruded or the dead corner of the cross-linked material staying in the flow channel for a long time. The old glue is amber, and the longer the residence time, the more The darker the color, the higher the temperature, the darker the color.
The last reason for the uneven surface of the cable insulation is the problem of the cooling process. Generally, during the production process, there are bubbles on the surface of the cable. When the cable enters the water, some of these bubbles will be small, but some will be smaller. It will adhere to the surface of the cable, and after the cable cools, a small bag will appear in this position. This is because the existence of air bubbles causes the insulating surface of this part to be covered with air, so it becomes uneven.
