Duplex Fiber Optic Cable Manufacturing: Common Problems and Solutions

Duplex Fiber Optic Cable Manufacturing: Common Problems and Solutions

For duplex optical cables , the quality of the outer diameter is a key factor in determining product quality . Its dimensional accuracy and shape regularity not only directly impact subsequent installation but also crucially influence the stability of signal transmission. Deviations in this process can lead to construction delays, or even lead to quality risks such as excessive transmission attenuation. Therefore, avoiding these common outer diameter issues during production is of great practical value in improving production efficiency and ensuring communication reliability .

Common Problems and Solutions

1. Outer diameter deviation

Problem: The dimensions exceed the standard tolerance range,resulting in reduced installation adaptability and affecting system compatibility.

Main reasons：Imbalance in the ratio of pulling and extrusion speed, insufficient calibration accuracy of the diameter gauge and fluctuation in the melt fluidity of the sheath material.

Solution :

• Equipped with a speed linkage control system to synchronize the traction and extrusion speeds, and strictly control the error within 0.5%;
• Diameter gauge are calibrated daily and make parameter corrections immediately when the detection error exceeds 0.02mm;
• Targeted addition of fluidity improvers and strengthening of melt index testing of raw materials before they enter the factory.

2. Poor roundness

Problem : The cross-section is not a perfect circle, resulting in uneven insulation protection and increasing the risk of mechanical damage.

Main reasons: insufficient mold precision or excessive wear, the bare optical fiber itself is out of roundness, the tight sleeve material is unevenly plasticized or contains impurities, and the tight sleeve material has abnormal lubrication.

Solution :

• Use high-precision molding dies and establish a regular (every 3,000 meters of production) inspection and replacement mechanism;
• Optimize mold flow channel design to improve melt filling uniformity;
• Strictly implement incoming inspection of bare optical fibers and reject fiber cores with excessive out-of-roundness (controlled at ≤0.5μm);
• Ensure that the sleeve material is fully plasticized (plasticization degree ≥ 95%), and strengthen raw material filtration and impurity detection;
• Precisely control the tight-fitting material lubrication system to avoid molding defects caused by insufficient lubrication.
• Check whether the bottom of the optical cable is neatly arranged. The distance between the optical cables should be 0. The maximum traction air pressure tension is 0.2. The smaller the optical cable winding tension, the better.
  

3. Adhesion problems

Problem : The core wire sheath and the outer coating are adhered to each other, which can easily cause micro-bending damage to the optical fiber during subsequent processing.

Main reasons: low melting point of the sheath material, insufficient cooling rate, mismatch of material hardness, and unreasonable process parameter settings.

Solution:

• Reduce the extruder head temperature by 5-10°C and control the first cooling water temperature at 15-20°C to increase the cooling rate;
• Apply special isolation agent evenly on the outer layer of the core wire (the dosage is controlled at 0.3-0.5g/m);
• Precisely adjust the mold concentricity (deviation ≤ 0.03mm);
• Strictly control the preheating temperature of PVC material at 60-70℃, and select outer coating material with Shore hardness of 55P-65P.

4. Rough or defective surface

Problem : Particles, cracks, bubbles and other defects appear on the surface of the sheath, reducing environmental resistance and service life.

Main reasons: insufficient plasticization degree of raw materials, unreasonable cooling process, and deviation in cross-linking parameter settings.

Solution :

• Increase the temperature of the plasticizing section of the extruder by 8-10°C to ensure that the raw materials are fully plasticized;
• Adopting a three-stage gradient cooling process (water temperature is 20-25℃, 30-35℃, 40-45℃);
• Monitor the cross-linking degree of cross-linked optical cables (controlled at 85%-92%) and regularly verify cross-linking equipment parameters;
• Implement a double inspection system for incoming raw materials (appearance inspection + impurity content inspection).

Addressing the outer diameter issues of 2.0 duplex optical cables requires comprehensive quality control throughout the entire process. By precisely adjusting equipment parameters, rigorously selecting raw materials, and regularly maintaining molds, stable outer diameter quality can be achieved. Implementing these measures in production effectively improves the mechanical performance and transmission stability of optical cables, laying a solid foundation for reliable communication network operation.