With the fierce market competition and the continuous development of the wire and cable industry, as well as users' growing awareness of cable product quality, user demands for cable products are no longer limited to price and cost alone. Increasing importance is being placed on both the internal and external quality of products. The required products must not only meet the relevant production technical standards (GB, JB, MT, etc.) in terms of intrinsic performance but also pay particular attention to their appearance quality. Issues such as bulges, dents, scorched particles, cold material lumps, rough wire drawing, and air holes in cross-sections are undesirable. The occurrence of such defects often leads to user dissatisfaction, raises doubts about the enterprise's product quality, and frequently results in user complaints or negatively impacts the company's image and market presence. In this article, the author shares some insights based on experience in addressing issues related to damage to the outer sheath of non-armored large-cross-section single-core cables, as well as practical production experience. The article offers a preliminary perspective on quality problems, cause analysis, and quality control during the production of non-armored large-cross-section single-core cables.

Characteristics and Process Features of Large-Cross-Section Single-Core Cables
Due to their inherent characteristics, large-cross-section single-core cables have a large cross-section, a high proportion of metal materials, and a relatively thin extruded sheath.

When extruding the sheath for large-cross-section copper single-core cables, a 150 extruder is typically used. The production process generally includes: insulation extrusion (including conductor shielding, insulation, and outer shielding) — copper tape shielding — sheath extrusion.

From the structural dimensions and extrusion production process of large-cross-section single-core copper cross-linked cables, it is evident that after sheath extrusion, surface cooling is required. Insufficient cooling of the sheath can lead to quality abnormalities such as surface wrinkling, breakage, and deformation of the sheath on the bottom layer of the cable reel.

Analyzing from the perspective of cable cooling and heat dissipation balance principles (Q released = Q absorbed = Q copper + Q water + Q others) and practical production experience, it can be generally concluded that, even under the same production speed and cooling conditions for products with similar extrusion outer diameters, armored cables have better heat dissipation and cooling effects compared to non-armored cables.

Analysis of Product Quality Defects and Process Control Measures
During the production of large-cross-section single-core cables, the main external quality defects include sheath wrinkling, holes, breakage, scorched particles, cold material lumps, rough wire drawing, excessive air holes in cross-sections, deformation of the sheath on the bottom layer of the cable reel, natural inflation and loosening of the sheath after sealing, and abrasion of the sheath on the sides of the cable reel.

Additionally, during the extrusion process, due to the cable's own weight, even if the eccentricity is adjusted correctly, the upper part of the sheath tends to be thicker while the lower part is thinner. Furthermore, compared to steel tape, copper tape has poorer heat dissipation, resulting in slower cooling under the same extrusion speed as armored cables. If the cooling water tank is not fully utilized during product extrusion, issues may arise. For instance, after passing through the spark tester and before winding onto the reel, the product appearance may not show significant abnormalities. However, after winding onto the reel, since not all reels are perfectly flat and the winding process can be irregular, the cable may sometimes rub against the sides of the reel. Additionally, the inner layers of the cable on the reel may experience shifting. If the cable sheath surface is not sufficiently cooled, wrinkling may occur, and in severe cases, abrasion between cables due to shifting may happen.

Regarding the quality issues of large-cross-section single-core cables, the author believes that whether in production or use, manufacturers, distributors, and users should have a basic understanding of cable characteristics and installation knowledge. In particular, cable manufacturers need to strengthen cause analysis and control during the production process, continuously summarize abnormal phenomena encountered in production, analyze their causes, and develop control measures. The goal is to reduce product quality defects and improve both the internal and external quality of the products.