Complete Fiber Fusion Process for Terminal Boxes

The fiber fusion process for terminal boxes involves precise fiber preparation, cleaning, cleaving, alignment, fusion, and protective termination to ensure low-loss, high-integrity splices.

1. Fiber Preparation

Stripping the Fiber: Use precision strippers to remove the fiber coating without damaging the glass core. Typical strip lengths are 10–20 mm depending on fiber type (single-mode or multimode) and splicer specifications. Apply uniform pressure to avoid microfractures that can degrade splice quality . Cleaning: Clean stripped fibers with lint-free wipes soaked in 99%+ isopropyl alcohol, wiping from the coating edge to the cleave tip in a single motion. Inspect under a microscope or splicer camera to ensure no dust, oil, or residue remains . Inserting Protective Sleeves: Before splicing, slide a heat-shrink splice sleeve onto one fiber end. This sleeve cannot be added after fusion, so proper placement is critical .

2. Fiber Cleaving

Use a precision cleaver to create a flat, perpendicular end face (<0.5° deviation). Ensure the fiber lies flat in the V-groove without tension. Inspect for chips or microcracks, as imperfections can increase insertion loss by 0.2–0.5 dB .

3. Alignment and Fusion

Loading Fibers: Place cleaved fibers into the splicer's V-grooves, aligning cores precisely to avoid splice loss. Maintain balanced tension to prevent microbends or breakage . Core Alignment: Modern splicers use 3D active core alignment or profile alignment for ribbon fibers. Some models use LID (Local Injection and Detection) to optimize light transmission . Arc Fusion: The splicer generates an electric arc to fuse the fiber ends, forming a molecular bond. Arc parameters (current and duration) are automatically tuned based on fiber type (SM/MM/APC) . Quality Verification: Splice loss is estimated by the splicer, and OTDR testing can confirm insertion loss (≤0.02 dB for SMF) and return loss (>60 dB for APC splices) .

4. Protective Termination in Terminal Boxes

Heat-Shrink Sleeve: Activate the splicer's heating device to shrink the protective sleeve over the splice, shielding it from moisture and mechanical stress . Fiber Management: Organize spliced fibers within the terminal box using trays or guides to prevent bending below the minimum bend radius. Secure incoming feeder cables and outgoing pigtails to maintain orderly routing . Environmental Protection: Ensure the terminal box housing is dust-proof, watertight (IP65/IP68), and resistant to temperature fluctuations (-25°C to 45°C) for outdoor deployments .

5. Final Checks

• Inspect all splices visually or with the splicer camera.
• Verify mechanical integrity (>95% of fiber tensile strength) and optical performance.
• Document splice locations and test results for network maintenance and troubleshooting . By following these steps, technicians can achieve low-loss, high-reliability fiber splices within terminal boxes, ensuring optimal network performance and long-term durability.