Two Ways to Join a Conveyor Belt
When a conveyor belt needs joining β whether installing a new belt, repairing a damaged section, or making an endless belt β there are two fundamentally different methods: vulcanized splicing and mechanical fasteners.
Both work. Neither is universally superior. The right choice depends on your application, your maintenance team's capabilities, and your priorities.
Vulcanized Splice
A vulcanized splice joins belt ends by bonding them with rubber compound under heat and pressure, creating a joint that is chemically part of the belt itself.
How it works: Belt ends are prepared by cutting steps into the carcass plies (step splice), applying rubber cement and bonding compound, overlapping the prepared ends, and curing under a heated press for 30β60 minutes at 140β150Β°C. The result is a joint with strength close to the belt's own tensile rating.
Strength: A properly made vulcanized splice achieves 85β95% of the belt's rated tensile strength.
Advantages: - Highest strength β approaches the belt's own rating - Smooth surface β no fastener hardware protruding above belt surface - Works with all belt scrapers without restriction - No risk of fastener corrosion - Preferred for high-speed belts (fasteners can cause vibration at speed) - No fasteners to catch on chute lips or transfer points - Required for many FRAS belt applications in underground coal mines
Disadvantages: - Requires trained personnel and proper vulcanizing press equipment - Takes 1β3 hours per splice (longer for wide, multi-ply belts) - Cannot be done quickly in an emergency without the right equipment - Higher initial investment in press and tooling - Requires belt to be stationary and the section to be accessible
Mechanical Fastener
A mechanical fastener joins belt ends by clamping metal fastener plates through the belt at both ends, linked by a hinge pin.
How it works: Fastener plates (typically steel or stainless steel) are pressed or bolted through both belt ends. The plates are hinged together with a steel pin. The result is a joint that holds the belt ends together mechanically.
Strength: Mechanical fasteners achieve 40β60% of the belt's rated tensile strength, depending on the fastener type and belt construction.
Advantages: - Fast installation β a mechanical splice on a 1000mm belt takes 20β30 minutes - No special equipment needed β a fastener press tool is inexpensive and portable - Easily replaced in the field if a fastener fails - Good for emergency repairs when vulcanizing equipment is not available - Lower skill requirement β most maintenance crews can learn mechanical splicing quickly
Disadvantages: - Lower strength β 40β60% of belt rating versus 85β95% for vulcanized - Hardware protrudes above belt surface β can interfere with some scrapers - Fasteners can catch on chute lips and transfer hood lips if clearances are tight - Corrode over time in wet applications β stainless steel fasteners help but cost more - Not suitable for very high-tension applications - Generally not acceptable for FRAS-certified underground coal mine applications - Not suitable for steel cord belts (the cords prevent fastener penetration)
Side-by-Side Summary
| Property | Vulcanized Splice | Mechanical Fastener |
|---|---|---|
| Joint strength (% of belt rating) | 85β95% | 40β60% |
| Installation time | 1β3 hours | 20β30 minutes |
| Equipment needed | Vulcanizing press, tools | Fastener press tool only |
| Skill level required | Trained splicer | Basic mechanical skills |
| Belt surface at joint | Smooth | Hardware protrudes |
| Scraper compatibility | Full | Restricted β scrapers must accommodate hardware |
| Emergency field repair | Difficult | Practical |
| Underground coal mine FRAS applications | Typically required | Often not acceptable |
| Steel cord belts | Yes | No |
| Cost of splicing | Higher (labor + equipment) | Lower |
| Long-term reliability | Higher | Lower β fasteners wear and corrode |
When to Use Vulcanized Splicing
High-tension conveyors. If your belt tension calculation shows working tension near the belt's rated strength, you need the 85β95% joint efficiency of a vulcanized splice. A mechanical fastener at 50% efficiency on a high-tension belt is a failure waiting to happen.
Steel cord belts. Steel cord belts cannot be mechanically fastened. Vulcanized splicing is the only option.
Underground coal mines with FRAS requirements. Most FRAS belt certifications require vulcanized splices for underground coal applications. Check your specific regulatory requirement.
High-speed belts. At belt speeds above 3β4 m/s, mechanical fastener hardware can cause vibration, noise, and impact on idlers. Vulcanized splices are smooth and don't create this problem.
Applications requiring full scraper contact. If you need scrapers to clean the full belt width without interruption, a smooth vulcanized splice is necessary.
Permanent installations. For a belt that will run for 5+ years in a fixed installation, a vulcanized splice will outlast multiple mechanical fastener replacements.
When Mechanical Fasteners Make Sense
Emergency repairs. If a belt fails at 2am and production needs to restart by morning, mechanical fasteners are the practical solution. A vulcanized repair press may not be on site or available on short notice.
Frequent belt changes. If your application wears through belts every few months, the time savings from mechanical fastening may outweigh the lower joint strength (assuming the strength is adequate for the tension).
Low-tension applications. On short, lightly loaded conveyors where working tension is well below belt capacity, mechanical fasteners' lower strength is not a limiting factor.
Operations without trained splicers. If your maintenance team cannot reliably make vulcanized splices, a mechanical fastener done correctly is better than a poorly made vulcanized splice.
Temporary or mobile equipment. For temporary conveyors or mobile equipment that gets reconfigured frequently, mechanical fastening is more practical.
Frequently Asked Questions
Can I switch from mechanical fasteners to vulcanized splices on an existing belt? Yes. You can remove mechanical fasteners, trim the belt ends, and make a vulcanized splice. The belt will be slightly shorter by the amount trimmed. Ensure you have enough belt tension take-up to accommodate the shorter length.
How long does a good vulcanized splice last? A properly made vulcanized splice in a well-maintained belt should last the life of the belt. Belt failure typically occurs in the belt itself (cover wear, carcass damage) before a good splice fails.
What causes mechanical fasteners to fail? Corrosion of the fastener plates or hinge pin, fatigue cracking of the belt cover at the fastener holes, and mechanical wear of the hinge pin are the most common failure modes. Regular inspection catches these before they become critical failures.
Do you supply mechanical fasteners as well as belts? Yes. We supply mechanical fastener sets compatible with standard EP belt thicknesses. Contact us with your belt thickness and width for a recommendation.