1. Plastic scorching of spiral cable
Plastic scorching is a common quality defect in the process of plastic extrusion, which mainly shows as follows: (1) the temperature is too high; The extruded plastic layer having coke particles; There are continuous bubbles at the glue joint. The main reasons are as follows: (1) the temperature control is too high to reach the thermal degradation temperature of plastics; The screw is not cleaned for a long time, and the accumulated combustibles are extruded by the molten plastic; The heating or stopping time is too long, so that the plastic in the barrel is heated for a long time and decomposed; The temperature control instrument is out of control or out of order, resulting in high temperature decomposition.
2. Poor plasticization of extrudate of spiral cable
Plasticization has been mentioned in the above temperature control requirements. Generally speaking, the poor plasticization is mainly manifested as follows: the surface of extruded coated plastic is black, matte, and there are small cracks; The extrusion coating has obvious joints at the glue joints; Nonstandard temperature control is the main reason for poor plasticization of extrudates, including: too low temperature control; Other plastic particles with different properties are mixed in the insulating or sheathing material; The screw rotates too fast, and the plastic cannot be fully plasticized; The plastic itself has quality problems.
3. There are holes or bubbles in the extruded coating part of spiral cable
The main reasons for the occurrence of air holes or bubbles in the extrusion cladding section include: high temperature control (especially in the feed section); Plastic is wet; Long time parking does not exclude the decomposition of plastic; High humidity of natural environment; There is water in the cable core or the content of vaporization is too high.
4. Unqualified extrusion package size of spiral cable
The unqualified size of extrusion packaging mainly shows that the eccentric core, jacket thickness and outer diameter are out of tolerance. The main reasons are: unstable extrusion and traction speed; The outer diameter of the cable core changes too much; The extrusion temperature is too high, which leads to the reduction of extrusion volume; Excessive impurities in the plastic will block the filter screen and reduce the plastic flow; Unstable winding and winding tension;
