Fiber optic cable granules in production

Fiber optic cable production begins with high-purity silica granules and polymer pellets, which are processed into preforms and coatings before being drawn into optical fibers. Raw Materials: Silica and Polymer GranulesThe primary raw material for fiber optic cables is ultra-pure silica (SiO₂) granules, chosen for their ability to transmit light with minimal loss. These granules are refined and deposited to form a preform, a cylindrical glass rod that serves as the precursor to the optical fiber.

The deposition process involves burning silicon-based gases to create pure glass particles, which are fused together to form a solid rod. For the protective layers, polymer granules such as polyethylene (PE), polyvinyl chloride (PVC), or low-smoke zero halogen (LSZH) compounds are used. These granules are melted and extruded to form the buffer coating and outer jacket of the fiber, providing mechanical protection, moisture resistance, and insulation.

Preform Creation and Fiber Drawing

The silica granules are transformed into a preform through precise deposition and fusion techniques. Once the preform is ready, it is placed in a high-temperature furnace (~2000°C), where the glass softens and is drawn into a thin fiber, typically 125 microns in diameter. The drawn fiber is coated immediately with polymer layers derived from the polymer granules to protect it from scratches and environmental damage.

Extrusion and Cable Assembly

After coating, fibers are stranded together and additional strength members like Kevlar, fiberglass rods, or steel wires are added. The polymer granules are again used in the extrusion process to form the outer jacket, ensuring durability and flexibility. Modern extrusion lines, such as those from Bausano or Rosendahl Nextrom, allow precise control over dimensions, fiber tension, and coating thickness, minimizing signal loss and defects.

Quality Control

Throughout production, the fiber and cable undergo rigorous testing. High-resolution monitoring systems measure fiber length, diameter, and coating uniformity in real time, reducing scrap rates and ensuring consistent performance. Water-blocking gels or tapes may also be incorporated to protect fibers from moisture.

Summary

In fiber optic cable production, silica granules form the optical core, while polymer granules create protective coatings and jackets. These granules are processed through preform fabrication, fiber drawing, coating, and extrusion to produce high-performance cables suitable for telecommunications, data centers, and industrial applications. The precision and quality of these granules directly impact the efficiency, durability, and signal integrity of the final fiber optic cable.