What is the effect of unqualified insulation thickness on the cable? What kind of sheath is qualified? How do we make qualified cables in production?

The hazard of unqualified sheath thickness

1, reduce the service life of wire and cable products

This is easy to understand, after long-term operation, especially directly buried, immersed in water, exposed to the open air or easily corroded environment, due to the corrosion of the external medium for a long time, the insulation level and mechanical level of the thin point of the sheath will decline.

Coupled with routine sheath testing or line grounding failure, the thin point may be broken down. In this way, the protective effect of the cable sheath will be lost. In addition, the internal consumption can not be ignored, wire and cable long-term power will produce a lot of heat.

2, increase the difficulty in the laying process

With the development of global industry, more and more environmental requirements of high-voltage cable products must be small outside diameter, in the laying process need to consider leaving a gap, so as to dissipate the heat generated after the wire and cable power, the thickness of the sheath is too thick will increase the difficulty of laying, so the thickness of the sheath is strictly in line with the relevant standards, otherwise it can not play a role in protecting the wire and cable. Nor can we blindly pursue its thickness.

What kind of sheath is acceptable?

According to the above two analysis, it is not difficult to see that the quality of the product is good or bad, its characteristics are reflected from the appearance quality of the product, no matter what kind of product, or semi-finished products, in the production must pay attention to the appearance quality, the implementation of strict control and inspection.

Sheath is the appearance of the cable, its appearance requirements are smooth and round, uniform luster, no deviation of the core (shall not exceed the specified deviation), no mechanical damage, flattening, no visual visible debris, bubbles, sand holes, obvious particles, bamboo, twist shape, etc. In addition to meeting the above quality requirements, the thickness of the sheath also has a certain impact on the quality of the cable.

As we all know, the role of the cable sheath is to protect the insulated wire core of the cable from damage under the action of external forces, and play a protective role. If the thin point of the cable sheath does not meet the requirements, the cable sheath is damaged under the action of normal external destructive force.

If the thickness of the sheath in the production of the cable is lower than the standard requirements, it is unqualified, and the thickness exceeds the standard requirements.

Several points to pay attention to in the production of sheathing

1. Calculate the thickness of the control sheath according to the standard formula: D (outer diameter before extrusion) ×0.035+1

2. Measure the sheath thickness online

Sheath thickness = (circumference after sheath extrusion - circumference before sheath extrusion)/2π

or

Sheath thickness = (circumference after sheath extrusion - circumference before sheath extrusion)×0.1592

3. Thin point of single core sheath: nominal value ×85%-0.1

4. Thin point of multi-core sheath: nominal value ×85%-0.1

5. Increase the temperature of the low-density polyethylene sheath extruder and improve the stress cracking strength, because the extrusion temperature is too high, easy to make the plastic scorch, or "slip" phenomenon; In addition, the shape stability of the extruded cladding is poor, the shrinkage rate increases, and even causes the discoloration and bubbles of the extruded plastic layer.

6. Do the extrusion body and screw cooling system to eliminate friction and overheating, in order to maintain the heat balance in the extrusion process, stabilize the extrusion pressure, promote the plastic mixing evenly, improve the plasticizing quality.

To sum up, in the production process, we only after careful operation of the equipment, according to the standard requirements of strict control of the thickness of the sheath, so that not only for the enterprise to save resources, reduce material consumption, increase profits, but also to ensure the quality of the cable, to create high-quality and inexpensive products.

Qingdao Tianxing Cable Co., Ltd. focuses on the production of customized wire and cable manufacturers, main: fire wire and cable, power cable, control cable and other products, exported to more than 40 countries and regions around the world, the annual production capacity of 1 billion yuan. 6000 square meters of storage, standing hundreds of millions of inventory, order demand for rapid distribution and delivery, large prices more favorable.