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Flexible flat conveyor belts (also called rod network belts) are designed for a long service life — yet unplanned downtime is common. The reason: most failures are caused by improper tensioning, installation errors, or worn drive components, not by the belt wearing out. In fact, nearly 90% of production belt failures occur at improperly tensioned splices. Below are the top ten causes of downtime, ranked by frequency, each with its impact and prevention strategy.
Quick Reference: The 10 Causes at a Glance
| # | Cause | Prevention in One Line |
|---|---|---|
| 1 | Excessive belt tension | Tension to recommended levels, especially after splicing |
| 2 | Insufficient clearance at Z-bends | Keep ≥1 mm between Z-bends and conveyor components |
| 3 | Worn drive components | Inspect and replace sprockets and rollers on schedule |
| 4 | Transfer/reverse bend radius too small | Meet or exceed minimum bend radius specifications |
| 5 | Wrong drive sprockets | Use sprockets engineered for this belt type |
| 6 | Misaligned sprockets | Use a keyed drive shaft; inspect alignment regularly |
| 7 | Wrong belt for the application | Reassess belt spec when operating conditions change |
| 8 | Belt installed upside down | Smooth surface up, Z-bend ridge underneath |
| 9 | Belt installed backwards | Loop edges must curve away from travel direction |
| 10 | No spare belt on site | Stock spares and connecting tubes near the point of use |
1. Excessive Belt Tension
Problem: Over-tensioning is a common issue, especially during hurried repairs. Excessive tension places undue stress on the wire strands, particularly at splice points.
Impact: Nearly 90% of production belt failures occur at improperly tensioned splices. Over-tensioning also causes work hardening in the wire, which weakens the belt.
Prevention: Adjust belt tension to the recommended levels. PFM SCREEN provides tensioning tools and expert advice to ensure proper installation. If you need to re-splice the belt, follow our step-by-step tube join guide.
2. Improper Clearance Between Belt Joints
Problem: Flexible flat conveyor belts require a minimum clearance of 1 mm between the Z-bends and conveyor components. Insufficient clearance causes contact, leading to wear and damage.
Impact: Friction between the belt and components weakens the Z-bends, causing premature failure and system downtime.
Prevention: Ensure all conveyor components are adjusted to provide adequate clearance.
3. Worn or Damaged Drive Components
Problem: Over time, drive sprockets, idler sprockets, and rollers wear down, causing poor engagement with the belt.
Impact: Worn components lead to belt misalignment, slippage, and increased stress on wire strands, eventually causing failure.
Prevention: Regularly inspect and replace worn drive sprockets and rollers. PFM SCREEN supplies durable drive components that reduce maintenance frequency and improve belt longevity.
4. Small Transfer or Reverse Bend Radius
Problem: A transfer or reverse bend radius that is too tight places unnecessary stress on the Z-bends of the belt.
Impact: This stress accelerates wear on individual wire strands, leading to wire breakage and unplanned downtime.
Prevention: Ensure the radius of every bend in the conveyor system meets or exceeds the recommended specification. PFM SCREEN can provide minimum bend radius guidelines and assist with conveyor design adjustments.
5. Using the Wrong Drive Sprockets
Problem: Generic sprockets not designed for flexible flat conveyor belts can cause belt climbing, slippage, or snapping.
Impact: Mismatched sprockets engage the belt improperly, creating operational instability and premature belt wear.
Prevention: Use only sprockets engineered by PFM SCREEN for flexible flat conveyor belts. These components provide a precise fit and smooth operation.
6. Misaligned Drive Sprockets
Problem: Drive sprockets that are not aligned produce uneven pulling forces, placing excessive stress on specific wire strands.
Impact: Misalignment results in belt skipping, excessive wear, and wire breakage, shortening the belt’s lifespan.
Prevention: Use a keyed drive shaft to keep sprockets consistently aligned. PFM SCREEN recommends regular inspection and offers alignment tools to maintain proper sprocket placement.
7. Using the Wrong Mesh Belt for the Application
Problem: Operating requirements change over time, but the conveyor may still be running a belt specified for an older application.
Impact: A belt too light for heavy-duty service wears out rapidly, while an overly robust belt strains conveyor components unnecessarily.
Prevention: Periodically reassess the conveyor’s operating conditions. Consult PFM SCREEN to select the optimal mesh size, material, and tensile strength — our measurement and identification guide lists exactly which specifications to record.
8. Upside-Down Belt Installation
Problem: A flexible flat conveyor belt has a smooth top surface and a Z-bend ridge on its underside. Installing it upside down leads to operational inefficiencies.
Impact: An upside-down belt causes poor product handling, uneven loading, and potential belt damage from misaligned contact with conveyor components.
Prevention: Always check belt orientation before running the conveyor. Visual markings provided by PFM SCREEN make it easy to identify the correct side during installation.
9. Installing the Belt Backwards
Problem: The single or double loop edges of the belt must curve away from the direction of travel. Installing the belt in the wrong orientation increases the risk of snagging.
Impact: Misaligned loops can catch on machine components or personnel clothing, damaging the belt or causing injuries.
Prevention: Inspect belt orientation during installation and train operators to identify the correct loop direction. PFM SCREEN offers installation guides and on-site training.
10. Lack of Spare Belts
Problem: When a belt fails unexpectedly and no spare is on site, the line stops until a replacement is delivered. Many businesses underestimate the likelihood of failure or cut inventory costs by not stocking spares.
Impact: Waiting for a replacement belt turns a 30-minute repair into days of lost production.
Prevention: Keep spare flexible flat belts — plus connecting tubes for quick splicing — near the point of use. PFM SCREEN provides customized inventory management solutions to help clients maintain appropriate stock levels.
Frequently Asked Questions
Q: What is the single most common cause of flexible flat belt failure?
A: Improper tensioning at splice points — nearly 90% of production belt failures occur there. Correct tensioning during installation and after every splice prevents the majority of downtime.
Q: How often should drive sprockets be inspected?
A: Include sprocket engagement, tooth wear, and alignment in your routine maintenance schedule — monthly for high-duty lines, quarterly for lighter service. Replace sprockets at the first sign of poor engagement rather than waiting for belt symptoms.
Q: What spares should we keep on site?
A: At minimum: one spare belt sized for your longest conveyor, a set of connecting tubes matched to your wire diameter, and one set of drive sprockets. This turns most failures into a same-shift repair.
Running into a failure mode not covered here? Send our engineers a photo of the damage along with your belt specifications — see How to Measure and Identify a Flexible Flat Conveyor Belt for what to record — and we will diagnose the root cause.
