How to insert the heat shrink tubing for fiber optic cable splicing

Insert the heat shrink tubing before splicing, center it over the splice, and heat it to secure the joint.

Step-by-Step Procedure

1. Prepare the Fiber: Strip the protective coating from the fiber ends and clean them with 99% alcohol to remove any debris or oils. Use a fiber cleaver to cut the fibers to the correct length for splicing . 2. Pre-Place the Heat Shrink Tubing: Before performing the splice, slide the heat shrink tubing onto one of the fiber ends. Never attempt to insert the tubing after the fiber end-face has been prepared, as this can damage the splice . 3. Perform the Fusion Splice: Insert the fibers into the fusion splicer, align them, and start the fusion process. Ensure the splicer settings match the fiber type (single-mode or multi-mode) and environmental conditions, adjusting for altitude or temperature changes if necessary . 4. Position the Heat Shrink Tubing: After the splice is complete, carefully slide the pre-placed heat shrink tubing over the fusion point. Center the splice within the tubing and gently straighten the fiber to avoid bends or stress . 5. Heat the Tubing: Place the tubing in the splicer's heating oven or a dedicated heat source. Follow the manufacturer's recommended temperature and time settings. Older ovens may require lower temperatures for longer durations (e.g., 125°C for 60 seconds), while modern ovens can heat tubing at higher temperatures (up to 240°C) in 10–25 seconds depending on the sleeve type . Ensure the adhesive inside the tubing flows properly around the fiber joint. 6. Coil and Secure Fibers in the Splice Tray: Once the tubing has shrunk and cooled, place the fiber and tubing into the splice tray. Start from the center and work outward, coiling excess fiber neatly to avoid compression or breakage. Use fixed slots or spiral wraps to maintain a logical layout and protect the fibers from environmental stress . 7. Seal and Test: Seal the splice tray if required, using raw rubber or other sealing methods to ensure it is airtight. Test the optical loss using an OTDR or optical power meter to confirm the splice quality .

Precautions

• Ensure the heat shrink tubing matches the fiber type and splice size to avoid mismatches .
• Keep fibers and splicing equipment clean to prevent dust contamination .
• Adjust heating time and temperature gradually; excessive heat or short cycles can result in incomplete adhesive flow or insufficient shrinkage .
• Avoid twisting or bending fibers excessively during placement in the tray . Following these steps ensures a secure, low-loss, and durable fiber optic splice with properly applied heat shrink protection.