Optical cable sheath production commonly faces issues such as surface defects, dimensional deviations, adhesion problems, and poor roundness, all of which can affect mechanical performance and signal reliability.

Surface Defects

Surface defects like pores, pinholes, bubbles, cracks, and rough surfaces are frequent in optical cable sheaths. These defects can compromise insulation performance, mechanical strength, thermal stability, and aging resistance. Causes include uneven extrusion parameters (temperature, pressure, speed), poor cooling control, and moisture in raw materials. High friction during extrusion can generate excessive heat, leading to burnt particles, while insufficient plasticization results in rough surfaces. Moisture in materials can vaporize during extrusion, forming bubbles that reduce dielectric strength and mechanical integrity .

Dimensional Deviations

Outer diameter deviations occur when the sheath dimensions exceed tolerance limits, affecting installation adaptability and system compatibility. Causes include imbalances between pulling and extrusion speed, inaccurate diameter gauge calibration, and fluctuations in melt fluidity. Solutions involve adding fluidity improvers, testing melt index of raw materials, and precise equipment calibration .

Poor Roundness

Sheath cross-sections that are not perfectly circular can lead to uneven insulation and increased mechanical damage risk. This is often caused by worn or imprecise molds, uneven plasticization, impurities in materials, or insufficient lubrication. Controlling the lubrication system and ensuring proper fiber arrangement during extrusion can mitigate these issues .

Adhesion Problems

Improper adhesion between the core wire sheath and outer coating can cause micro-bending damage to optical fibers. Causes include low melting point of sheath material, slow cooling rates, material hardness mismatch, and incorrect process parameters. Solutions involve strict preheating temperature control and selecting materials with appropriate Shore hardness .

Preventive Measures

• Maintain dry, clean, dust-free, and oil-free environments for raw materials.
• Control granulation and extrusion temperatures to prevent moisture-induced defects.
• Implement double inspection systems for raw materials, checking both appearance and impurity content.
• Regularly maintain molds and extrusion equipment to ensure dimensional accuracy and surface quality.
• Optimize extrusion parameters such as speed, pressure, and cooling to achieve uniform sheathing . By addressing these common problems through careful material handling, precise equipment control, and rigorous quality inspections, manufacturers can improve the mechanical performance, environmental resistance, and signal stability of optical cables, ensuring reliable network operation.