New conveyor belts arrive as a long, rolled-up piece of material. To form an endless loop on the conveyor, belts are spliced. Splices join the belt ends for installation and repair.

Splices can be mechanical (joined with hardware) or vulcanized (joined through heat and bonding agents). Cost, time, available expertise, conveyed material and environment, and the age of the belt influence which splice is best for the job.

No matter the method, a belt’s splice is its weakest point. Poor splices cause belt failure, downtime, chatter, mistracking, and abrasion. In high-throughput industries, such as recycling or mining, poor splices translate to lost profit.

We’ll discuss different splicing methods: their advantages and disadvantages, the tools you’ll need, how to perform them, and some helpful tips to make your splices last.

Mechanical splices

Mechanical splices use fasteners and connectors (typically stainless steel), such as butterfly buckles and wolf teeth, to form a reliable belt joint. No expertise or special equipment is required, and mechanical splices are compatible with all belt widths, thicknesses, lengths, speeds, and tensions. They form a joint 55–65% of the belt’s strength.

Types of mechanical splices

There are too many mechanical splices to list, but some of the most common choices include the following:

• Alligator staple splices: easy, economical, low-profile belt splice.
• Super-screw splice: quick to install, thin, and fully integrated into the belt for enhanced stability.
• Bolt-hinged splices: allow for length adjustments. Joints can be easily separated by removing the hinge pin.
• Rivet-hinged splice: used on rubber-plied and PVC solid woven belts.
• Rivet plate fastening system: for high-tension applications.

Advantages of mechanical splices

Here’s why mechanical splices are popular:

• Cheap
• Quick installation
• Require little equipment
• Compatible with most belts
• Require less expertise
• Produce less belt waste (due to cutting)
• Easy to inspect for damage
• Effective with old, dirty belts

Mechanical fasteners are the go-to choice for quick belt fixes.

Limitations of mechanical splices

While quick and cheap, mechanical splices have the following downsides:

• Lower strength (55–65% of the belt’s strength) than vulcanized splices
• Shorter lifespan
• Temperature limitations (heat transmission weakens surrounding fibers)
• Prone to material leakage

Despite their limitations, mechanical splices perform reliably in most normal operating environments and with most materials.

How to perform a mechanical splice

While each mechanical splice features different attachment mechanisms, here are the basic steps on how to mechanically splice a conveyor belt:

1. Square and clean the belt ends.
2. Calculate the splice length.
3. Align the belt ends.
4. Install the fasteners:

1. For staple-type fasteners, position the staples, drive them through the belt material, and bend the legs on the opposite side.
2. For hinged fasteners, install the fastener plates on both belt ends and insert the hinge pin to connect the two sides.
3. For solid plate fasteners, position the plates on both sides of the belt and secure them using bolts or rivets.

1. Check the splice for proper installation and alignment.
2. Run the belt at low speed to check for proper tracking and function.

Conveyor belt splices should be regularly checked as part of routine maintenance.

Vulcanized splices

Vulcanization employs heat, pressure, and bonding agents to join the belt ends. While more time-consuming and equipment-dependent, vulcanized splices are much stronger than mechanical splices. There are two types of vulcanized splicing:

1. Hot vulcanization involves applying a patching material and melting it to fuse the belt ends. This conveyor belt splicing method is the most durable but requires specialized equipment and a clean environment.
2. Cold vulcanization involves using bonding agents or adhesives to rejoin the belt. This is done at room temperature. Cold vulcanization is quicker and simpler to perform than hot vulcanization, but it is somewhat weaker.

Vulcanized splice patterns

Whether hot or cold, vulcanized splices involve cutting the belt in different patterns to strengthen the splice. Here are some of the most common splice patterns:

• Longitudinal splice: a straight splice running parallel to the belt's length. It joins belt sections side-by-side or repairs longitudinal tears.
• Diagonal splice: an angled splice that evenly distributes stress across the belt width, reduces the impact on scrapers, and improves durability.
• Finger splice: belt ends are cut into interlocking finger-like patterns, creating a larger bonding surface area and a stronger, more flexible joint.
• Step splice: belt layers are cut in a stair-step fashion and overlapped, creating a gradual transition between the joined sections for improved strength and flexibility.

Splice patterns increase surface area, distribute stress, and form interlocking sections to maximize the security and longevity of the splice.

Advantages of vulcanized splices

Here’s why vulcanized splices are popular:

• Stronger (70–80% of the belt’s strength for cold, 80–90% for hot)
• Longer lifespan
• Less material loss (sift-through)
• Tolerant to hot, heavy, and abrasive materials/environments
• Smooth joint
• Effective with PVC belts

The reliability and durability of vulcanized splices are their main advantage.

Limitations of vulcanized splices

While long-lasting and strong, vulcanized splices have the following downsides compared to mechanical splices:

• Higher cost
• Require special equipment
• Require technique and expertise (especially for cold vulcanization)
• Require more downtime
• Hard to inspect for damage
• Require a clean, undamaged belt and a clean working environment

How to perform a hot vulcanized splice

While different splice patterns and bonding agents are used, these are the general steps for splicing a belt with hot vulcanization:

1. Preparation: power off the conveyor system and secure the work area. Loosen the counterweight device and fix the conveyor belt in place. Gather the required tools and clean the area of the belt you will work on.
2. Marking and alignment: draw the centerline of the belt. Mark reference lines and joint lines. Line up the belt ends.
3. Belt end preparation: cut grooves and pull out wire ropes (if applicable). Trim the steel cords and fabric plies. Strip the belt ends to expose plies.
4. Application of bonding materials: apply cement, tie gum, or other bonding materials. Build up layers of rubber and bonding agents.
5. Assembly: overlap the prepared belt ends. Align and position the splice materials.
6. Vulcanization: place the splice in a vulcanizing press.
7. Apply heat and pressure: temperatures typically range from 120 to 200°C (250 to 400°F). Pressure ranges from 34 to 1200 kPa (5 to 175 psi). Cure for the specified time according to belt type and thickness.
8. Cooling and finishing: allow the splice to cool. Inspect for defects. Buff away excess rubber.
9. Final inspection and testing: check the splice quality. Test the belt at low speed to check performance.

Belt mistracking may indicate a crooked splice.

How to perform a cold vulcanized splice

A cold vulcanized splice follows most of the same steps as a hot one. The difference is that, after the bonding agent has been applied and the splice has been assembled, the belt is clamped and left to dry instead of being placed in a vulcanizing press.

Cold vulcanization is quicker and requires less equipment, but the connection is less stable. A good cold splice requires a temperate environment, a deep knowledge of solvents, and precise belt cuts.

Splicing tools

Splicing requires special tools. Here are the most common tools and their roles in splicing:

• Belt cutters: the splicing tool used for cutting industrial conveyor belts. They come in three types: manual, electric, and hydraulic.
• Belt skivers: they remove the top cover of the belt before splicing. This is done to create overlap for a seamless joint. There are two types of belt skivers: handheld and bench-mounted.
• Belt clamps: they hold the belt ends together while splicing.
• Vulcanizing presses: for hot splicing, they bond the belt ends using heat and pressure. They come in two types: hydraulic and electric.
• Hand tools: for mechanical splices, screw drivers, hammers, and staplers are the most common installation tools.
• Bonding agents: adhesives, gums, and solvents provide chemical bonding to seal the belt ends for a vulcanized splice.
• Non-leaded petrol: used as a cleaning product.

Check with your conveyor belt manufacturer for recommended tools and splicing techniques.

Mechanical vs. vulcanized splices

If you’re still not sure which splice is right for you, here’s a reference chart to summarize the differences between mechanical and vulcanized splices.

Vulcanized splices

Mechanical splices

• Strength
• Stronger (70–90% of belt strength)
• Weaker (40-50% of belt strength)
• Lifespan
• Longer
• Shorter
• Material loss
• Less sift-through
• More potential for material loss
• Environmental tolerance
• More tolerant to extreme conditions
• Less tolerant to extreme conditions
• Joint smoothness
• Smooth
• May have protrusions
• Compatibility
• Works with most belts
• Works with most belts
• Cost
• Higher
• Lower
• Equipment needs
• Requires special equipment
• Simple tools
• Expertise required
• High (especially for cold vulcanization)
• Less technical skill needed
• Downtime for installation
• Longer
• Shorter
• Damage inspection
• Difficult to inspect
• Easier to inspect
• Belt condition requirements
• Clean, undamaged belt needed
• Can be used on older or worn belts
• Working environment
• Clean environment required
• Less sensitive to dust or other contaminants, within reason
• Installation speed
• Slower
• Faster
• Flexibility for field repairs
• Less flexible
• More suitable for on-site repairs

Splicing tips

A successful belt splice depends on having the right approach. Here are some tips to help you maintain efficient operations and produce safe, long-lasting splices.

Don’t wait

Regular inspections allow technicians to spot weak splices before they fail. This allows you to schedule downtime that doesn’t cause unexpected financial loss.

Clean the area

Vulcanized splices require a clean belt and environment. While mechanical splices are more forgiving, it is best to clean the belt and perform the splice in a controlled environment. Workers should remove belt oils and greases and avoid splicing in extreme heat or adverse weather.

Focus on the cut

Flawless cuts and belt end preparation determine the longevity of the splice. Whether you’re using a 22-degree bias cut or finger lacing, preparing the belt ends without damaging the fabric plies should be done slowly, carefully, and by an experienced technician.

Use less adhesive

Less experienced technicians often over-apply adhesive. This produces a weaker (rather than a stronger) bond. Apply a solid layer of adhesive, and let it do its job.

Consult the belt manufacturer

Manufacturer-recommended curing times and procedures usually produce the strongest splice. Talk to the belt manufacturer before splicing the belt to discuss special instructions and curing times.

Use the center line

All measurements and marking lines should reference the belt's center line, not its edges. This approach creates straight splices even when belt edges aren't parallel.

Keep it professional

Choose a supplier that carries high-quality replacement belts and provides continuous support. At Fluent Conveyors, we’re happy to guide you through the belt replacement and splicing process. We stand behind the quality of our products and our customer service.

Contact us online, or call us at (866) 764-2980 and we can discuss your belt replacement and splicing options.