Quick Answer: Six Failure Patterns
A cleat that comes off is usually blamed on the weld because that is the visible line. In practice, the cleat may have been asked to do a job the belt surface, profile or cure schedule could not support. The fastest way to stop repeat failures is to read the peel pattern: an edge lift, full release, base crack and cover tear point to different corrections.
Key Takeaways
– Start with the failure surface: edge lift, full release, base cracking and belt-cover tearing have different causes.
– Clean, dry, freshly prepared material is the first requirement; heat cannot compensate for a contaminated interface.
– A taller cleat increases the bending moment at its base, so height and base width must be checked together.
– Re-weld only when the cleat and belt cover are sound; a detached cleat is often a symptom, not the whole fault.
Which are the 6 main reasons cause cleats falling off?
The six patterns to check are poor surface preparation, wrong temperature or dwell time, cleat material mismatch, excessive profile and load stress, belt contamination or moisture, and handling the belt before the joint has cooled or cured.
The pattern is more useful than the calendar. A cleat that peels after two days and a cleat that peels after two years can both be described as “coming off,” but they rarely have the same root cause.
Poor Surface Preparation Before Welding
The cleat base and belt cover must make intimate contact across the full footprint. Dust, oil, mold release, chalk, product residue and moisture all interfere; a surface that looks clean can still carry a film that stops a bond.
Too little preparation leaves contamination and a low-energy surface. Too much grinding removes the cover, changes the profile and generates heat. Use the belt maker’s method, keep the abrasive clean and expose a fresh surface immediately before welding. Handle the bonding face with clean gloves and keep it away from silicone sprays, release agents and workshop dust.
Wrong Temperature or Dwell Time
Welding is a time-temperature-pressure process. Too little heat leaves an incomplete melt; too much degrades the polymer. Too little pressure leaves voids; too much pushes melt out of the joint.
HOLO’s cleat welding machine comes in 2 m and 3 m models, uses 5.5 kW at 220 V single phase, handles PVC/PU belts from 2 mm to 10 mm and welds at up to 2 m/min. Those are machine limits, not a recipe. Run a test on scrap from the same belt and cleat: an incomplete weld releases cleanly, while an overheated weld may look glossy, discolored or brittle.
For vulcanized rubber cleats, use the compound supplier’s cure. HOLO’s CBP-1220*200 press has a recommended temperature of 145°C, a 0–200°C range and a 0–99 minute timer. The belt maker’s data should determine the cure, not the cleat’s surface temperature.
Cleat Material Mismatch
PVC and PU are thermoplastics; rubber is a thermoset. A PVC or PU cleat can be welded to a compatible thermoplastic belt, while rubber needs a vulcanized or approved chemical bond. A rubber cleat welded to PVC may pass a visual check but is not a structural joint.
The label is not enough. Covers can be blends, and a “PU” belt may have a different bonding layer or proprietary topcoat. Ask the belt maker for the actual polymer and attachment method, and test a sample if the belt is unknown. Cleat hardness matters too: a hard cleat on a flexible belt concentrates stress at the base, while a soft cleat may lift at the leading edge.
Cleat Profile and Load Stress
A cleat is a lever. At the same load and base width, doubling cleat height roughly doubles the bending moment at the root. A tall, narrow cleat therefore has a harder job than a short, wide one. A sharp internal corner concentrates stress, and a cleat that is too stiff for the pulley may crack as the belt flexes.
Check product weight, belt speed, incline, filling method and pulley diameter. If the cleat fails at the base rather than the bond line, changing temperature will not solve the design problem. Reduce height, widen the base, change the profile or revise the pitch.
Belt Contamination and Moisture
Water is destructive because it can be invisible. A belt stored in a humid area or washed before maintenance may look dry while the carcass holds moisture; under the platen it turns to steam and creates voids. Oil, grease, food residue and condensation do the same.
Let a cold belt reach room temperature and confirm the area around the cleat is sound before preparation. If a cleat peels with belt cover attached, the cover may already be degraded by oil, heat or cleaning chemicals. Replacing the cleat without repairing the cover only moves the failure.
Cure Time and Handling Too Soon
The joint may look finished while it is still developing strength. A thermoplastic weld must cool under pressure; a vulcanized rubber bond must complete its cure. Running, tensioning or loading the belt too early can open the interface.
Follow the machine maker’s cooling instructions and the compound supplier’s cure schedule. “Cool to touch” is not a strength test, and the timer should not be set from the previous job. Do not use the conveyor as a curing rack: support the belt, keep the joint out of tension and record when it returned to service.
Our finding: Edge peel is often blamed on the weld, but the real damage is frequently in the belt cover. A trimming burr, an over-ground edge or a contaminated cloth can leave a thin weak line around the cleat base. The cleat stays attached in the center while the edge lifts first.
Conveyor Belt Cleat Welding MachineConveyor Belt Cleat Welding Machine
LEARMORE
• Designed for cleat & guide welding where HF welding machines are not applicable.
• Ideal for wide conveyor belts, anti-static belts, and special cleat materials.
Repair vs Replace Decision
Repair is reasonable when the cleat is intact, the cover is sound, the failure is local and the material can be re-welded. Remove the old cleat and bonding layer without gouging the belt, re-prepare the surface and reproduce the validated settings.
Replace the cleat or section when the carcass is exposed, several cleats are lifting, the cover is delaminated, or rubber cleats cannot be re-bonded reliably. If the pattern no longer fits the product, replacing one cleat only restores the problem.
| Situation | Repair | Replace | Reason |
|---|---|---|---|
| One cleat, sound belt cover | Yes | No | Local re-weld can restore the joint |
| Several cleats lifting in one zone | Inspect | Usually | Pattern or belt-cover problem is systemic |
| Carcass exposed or torn | No | Yes | The belt cannot carry the cleat load |
| Rubber cleat on rubber belt | No | Yes | Re-weld is not the correct process |
| Cleat intact, wrong profile | No | Yes | Same failure will return |
The Downtime Cost of a Detached Cleat
A cleat is inexpensive compared with the conveyor stopping. The real cost includes lost production, labour, cleanup, possible belt damage and a downstream jam. Use a simple estimate:
Failure cost = downtime hours × line contribution per hour + labour + scrap + expedited parts
If a line contributes $2,000 per hour and is down for four hours, downtime alone is $8,000 before anyone replaces the cleat. That changes the repair decision. A lower-cost cleat that does not match the belt polymer can save a few dollars per piece and cost a full shift in rework.
Prevention Checklist
- Identify the belt polymer and cleat material first.
- Confirm height, base width and pitch against the product and pulley path.
- Prepare the full footprint and protect it from dust and moisture.
- Verify platen temperature and pressure across the width.
- Run a peel test when the belt batch changes.
- Cool or cure fully before tensioning or loading.
- Inspect after the first shift and again after the first week.
- Record the failure with a photo, peel pattern and running hours.
See the cleat welding guide for the process steps, and use the failure pattern above to decide whether the next repair should be a re-weld or a belt change.
Need a Cleat Failure Review?
Send us the belt material, cleat profile, belt thickness, pulley diameter and photos of the peeled surface. We can help select the right welding or vulcanizing process and the machine configuration for the duty.
FAQ – Frequently Asked Questions
1. Why do welded cleats peel off at the edges?
The edge is where the bond ends and stress concentrates. Contamination, a trimming burr, an over-ground cover or uneven pressure can leave a weak line around the base. The center may stay attached while the edge lifts.
2. Can a detached cleat be reattached?
Yes, if the cleat is intact, the cover is sound, the materials match and the old bonding layer can be removed safely. If the carcass is exposed, the cover is delaminated or several cleats are lifting, replace the section or belt.
3. Does cleat height affect detachment risk?
Yes. A taller cleat is a longer lever, so the same load produces a larger bending moment at the base. It needs a wider base, a suitable profile and a belt that can flex around the pulley without cracking.
4. How long should cleats cure before use?
Follow the belt and cleat supplier’s schedule. A thermoplastic weld must cool and stabilize under pressure; a vulcanized bond must complete its cure. Do not use “cool to touch” as a proxy for full strength.
