Grinding the rubber ring of fiber optic patch cord

Grinding or polishing the rubber ring of a fiber optic patch cord requires careful use of a polishing machine, proper jigs, and controlled pressure to ensure optimal connector end-face quality.

Purpose and Context

The rubber ring on a fiber optic patch cord, often part of the ferrule assembly, helps maintain alignment and protects the fiber end. Grinding or polishing it is typically done during connector end-face preparation to remove excess epoxy, smooth the surface, and achieve a mirror-like finish that ensures low insertion loss (IL) and high return loss (RL) .

Tools and Materials

• Polishing machine: Foursquare or PLC-controlled units for repeatable polishing
• Polishing jigs: Individual Pressure Control (IPC) fixtures or standard jigs to hold ferrules securely
• Polishing films: Silicon Carbide or diamond lapping films, matched to the machine and connector type
• Polishing pad: Rubber pad to provide uniform pressure and prevent damage to the ferrule
• Polishing liquid: Recommended by the machine manufacturer to reduce friction and improve surface finish
• Air gun: To remove debris and dry the connector after polishing

Step-by-Step Procedure

1. Initial Preparation: Cleave the fiber and assemble the connector with the rubber ring, ferrule, and epoxy properly cured .
2. Manual Pre-Polish: Start with light hand polishing on the rubber pad using a coarse lapping film to remove sharp edges and epoxy protrusions. Rotate gently for about 10 turns to ensure uniform fiber protrusion .
3. Machine Polishing: Place the connector in the polishing jig. Adjust pressure, speed, and time according to the machine specifications. Use the same film as in the pre-polish step for consistency .
4. Epoxy Removal: If epoxy remains on the chamfer or base of the ferrule, carefully remove it with a scalpel or fine abrasive before proceeding to final polishing .
5. Final Polish: Use finer polishing films to achieve a mirror-grade finish. Ensure the rubber ring is not damaged and maintains proper alignment. Check that all ferrules are at the same height and move freely in the jig .
6. Cleaning and Inspection: Blow off debris with an air gun and inspect the end-face under a microscope to confirm smoothness and absence of scratches or epoxy residues .

Precautions

• Avoid excessive pressure that can deform the rubber ring or ferrule .
• Use only recommended polishing films and liquids to maintain quality .
• Ensure the ferrule is properly seated in the jig to prevent uneven polishing .
• Replace polishing films after multiple uses to avoid surface defects . By following these steps and using the correct equipment, the rubber ring and ferrule end-face can be polished effectively, ensuring high-quality optical performance and compliance with standards such as Telcordia GR-326-CORE and IEC 61300-3-35 .