Rubber Conveyor Belts: Problem Solving

Conveyor belts are a very useful resource in improving production processes but they also present a number of problems that can affect employees causing injuries or stop the production line and incur repair costs and production losses.

Choosing the right conveyor belt manufacturer and designing a system tailored to the specific needs of the handling application helps to maintain efficiency and extend the life of the equipment. However, even the best conveyor belts can have problems due to normal wear and tear or unforeseen changes in production.

Responding quickly to a problem with an underperforming or jammed conveyor belt is important to minimise downtime and prevent further damage and loss. So when a problem occurs, it is crucial to know where to start to fix it.

Fortunately, the rubber conveyor belt can be a reliable indicator because it can indicate the underlying problem through the wear pattern, operating problems, etc.

The following is a guide to quickly assessing and resolving the most typical problems that occur with the rubber conveyor belt.

 

Troubleshooting on a rubber conveyor belt

During the inspection of the rubber conveyor belt or rubber conveyor belt, attention must be paid to to any abnormalities such as atypical odours, leaks, sounds or wear and tear that can be observed with the naked eye that may indicate that something is wrong. Other possible problems include excessive material spillage, process bottlenecks, a change in product quality or other signs of poor performance. For troubleshooting, it is always recommended that all necessary safety measures are taken and it is important that operators and maintenance personnel are trained on the system to enable them to safely troubleshoot any problems that arise.

 

Common rubber conveyor belt operating problems

Belt slipping off one side of head or tail pulley

Possible cause: When a conveyor belt runs off one side of the end pulley, it indicates that something is wrong with the pulley itself. This type of belt behaviour is typical when the pulley is not square to the belt shaft, or when the pulley shaft is not transversely level. Material build-up, wear or lack of lagging can also cause this failure.

Solution: Confirm that the pulley shaft is horizontally level. Several rollers should be used before the pulleys to train the belt. It is recommended to improve cleaning procedures in case of material build-up and replace worn or missing lagging if necessary.

The belt runs to one side at a specific point on the frame.

There are many possible reasons why a belt moves towards a particular point on the frame. These include:

Possible cause: The rollers upstream of the problem point may not be square to the frame.

Solution: Minimally advance the end of several idler rollers on the outfeed side.

Possible cause: Conveyor frame may be misaligned or not transversely level.

Solution: Use a string to check the alignment along the conveyor. Use a level to check alignment across the width of the frame. Adjust the alignment as necessary.

Possible cause: There could be a build-up of material on the rollers or the rollers could be damaged or frozen.

Solution: Improve maintenance practices and/or install a cleaning device, such as a belt cleaner.

Possible cause: Terminal pulley may be misaligned.

Solution: Check and adjust both terminals.

Possible cause: Spilled material may be forcing the belt to move to one side.

Solution: Find and correct the cause of the spill.

The entire conveyor belt or a segment of the conveyor belt moves to one side (deflection).

Again, there are many factors that can cause the whole conveyor belt or a long section of it to move to one side:

Possible cause: The structure may be misaligned, or not transversely level.

Solution: Check and correct.

Possible cause: The belt may not be cut and spliced square. Also, the belt may be bowed as a result of poor storage conditions.

Solution: In the case of new conveyor belts, work with full load tension during the running-in period. If the problem persists, a new belt of higher quality may be necessary. In the case of bowed conveyor belts, a complete replacement is necessary.

Possible cause: Material is being loaded onto the conveyor belt off centre.

Solution: Correct the cause at the charging point.

Possible cause: The belt is incorrectly tensioned.

Solution: Adjust the pulleys as necessary.

The belt runs erratically 

Possible Cause: The belt may be too stiff. Also, improper belt tension could be causing the belt to malfunction.

Solution: Check belt manufacturer's quality of belt for proper specifications on conveyor. Check belt tension and adjust pulleys as necessary.

Possible cause: Frame twisting on portables and stackers.

Solution: Reinforce the loading hoppers so that the load and loading stresses do not allow the frame to twist out of line. Adjust belt tension.

 

Rubber conveyor belt wear problems

Excessive stretching 

When a belt is overstretched, there are two main causes:

1. Belt tension is too high.

   There are many factors that can cause the tension to be too high and therefore there are many possible ways to solve the problem:

   • Increase the belt speed while maintaining the same capacity.
   • Reduce tonnage while maintaining the same speed.
   • Install a drive pulley liner.
   • Use less weight in the gravity socket, or less tension in the screw socket.
   • Check for worn rollers or spilled material.
   • Check tonnage capacity and belt tension against belt specifications.
   • Check the stresses in the flaps.
2. The construction of the strap is too light.

   To confirm that the belt construction is too light, the tonnage capacity and belt tension should be checked against the belt specifications. The solution in this case is to replace the belt with one of suitable specifications.

Belt shows heavy wear on pulley side

Possible cause: The rollers may be jammed, or the impact or loading areas may be worn. Overloading may also be occurring.

Solution: Replace rollers in poor condition. Improve maintenance practices. Reduce load if necessary.

Possible cause: Material is allowed to spill onto the return conveyor.

Solution: There are many possible ways to resolve material spillage on the belt. These include:

• Use of a sealed hopper
• Installing a self-cleaning tail pulley
• Covering the return tape
• Avoiding careless loading with deep channel rollers
• Adding a return plough before the tail pulley

Possible cause: Head pulley fasteners may be protruding.

Solution: Replace the worn liner.

Possible cause: There may be slippage in the drive pulley.

Solution: Use a rubber lining on the drive pulley. Use grooved or herringbone type. If necessary, fit an idler pulley to increase drive pulley contact.

There are short breaks in the casing 

Possible cause: As with the previous problem, breaks in the casing could indicate a load impact from sharp lumps.

Solution: Reduce the impact of the load and use impact rollers or bed rollers.

Possible cause: The strap chosen does not fit the application.

Solution: Replace the belt with one more suitable for the application.

Possible cause: It is also possible that there is material between the belt and the pulley.

Solution: Improve maintenance practices to reduce fugitive material between belt and pulley.

Breaks occur at the belt edge

Possible cause: Belt edges may be bending in the structure at or near the pulleys.

Solution: Retighten the belt correctly.

Possible cause: Material jamming under the hopper or skirt boards.

Solution: Adjust the appropriate clearance and relief.

Possible cause: End idler pulley too close to head pulley or too high.

Solution: Adjust the location or height of the end idler pulley.

Possible cause: There is a sharp, convex curve in the system.

Solution: Adjust to a more gradual curve.

Belt edge shows wear

Possible Cause: When a belt shows edge wear, it is usually a sign of misalignment, which can allow the belt to slip out of line and rub against a structure.

Solution: Follow OEM recommendations to correct belt alignment. Realign if necessary.

The strap has transverse tears near the fasteners

Possible cause: The clamping plates are too long for the size of the pulley.

Solution: Use a correct cord and/or use larger pulleys.

Excessive hollowing

Cupping occurs when the edges of the belt curl. Normal wear and tear is to be expected over time, but excessive cupping can be an indication that something is wrong. There are many reasons for this:

Possible cause: Belt may be over tensioned.

Solution: Reduce belt tension or gravity belt counterweight. Check for drag from jammed rollers. Reduce load rate or increase belt speed to reduce tension. Ensure that the belt is suitable for the tension requirements.

Possible cause: Deep transition rollers and low elasticity in the belt fabric are causing high tension.

Solution: Use adjustable transition rollers at the terminals to achieve longer transitions between the deep groove and the pulleys. Use belts with moderate elasticity. Ensure adequate transition distances.

Possible cause: Stretched or worn belt.

Solution: Replace the belt.

Possible cause: The top cover is too heavy for the thin belt.

Solution: Consult a quality belt manufacturer.

The belt is hardening and/or cracking

Hardening and/or cracking of a rubber conveyor belt is the result of exposure to heat. To solve the problem, a belt of hot neoprene material and oil should be used for lubrication.

 

Tyre compound wear problems

The casing is swollen or blotchy

Possible cause: Spilled oil or grease is or has been on the belt.

Solution: Locate the source of the spill/leak and improve clean-up practices.

Possible cause: Trough rollers may be over-lubricated.

Solution: Improve maintenance practices.

Possible cause: There may be oil in the material.

Solution: Eliminate the source of oil if possible. If this is not an option, replace the belt with oil resistant covers suitable for the application.

Cover is cutting or slashing

Possible cause: When the cover is showing cuts or cracks, this could be the result of an impact from sharp material.

Solution: If this is the case, impact rollers, loading tables or cradles can be added. Some narrower belts or belts with lighter loads may require a softer drop zone (no horizontal roller) in the loading zone. The design of the chute could also be modified to allow better delivery of the material to the belt. A slope could also be added to the chute to allow the material to slide over the belt more smoothly.

Possible cause: Trapped iron or other material could also be causing the cut/breakage.

Solution: Use a metal detector or a magnet on the top of the head pulley.

Top cover shows wear (grooves, scoring, longitudinal tears or detachments) 

One of numerous factors may be at play, causing wear of the top cover:

Possible cause: The rubber on the hopper or skirt board is too stiff when pressed.

Solution: Use flexible skirt board rubber and adjust properly, adjust the skirt seals for minimum clearances, and/or install slides in place of the outer raceway rollers.

Possible cause: There may be a gap between the rollers at the loading point, allowing the material to grind between the belt and the flashing.

Solution: Space the rollers further apart at the loading point and set the appropriate clearance.

Possible cause: The metal of the skirt board is too close to the belt.

Solution: Set the right distance.

Possible cause: The width between the flaps is too narrow.

Solution: Widen the gap and narrow the opening in the direction of belt travel.

Possible cause: Belt deflects at the loading point allowing material to jam between the seals and the belt.

Solution: Use a loading hopper with belt edge guides, or move the roller or chute so that the impact of the load is just in front of the roller.

Possible cause: Material jammed against belts on head pulley in full hopper or plugged chute.

Solution: Add switches for the clogged weir, and observe more careful operation.

If the wear on the top cover is excessive, there could be another reason for the problem, such as:

Possible cause: The return rollers may have a build-up of material, causing them to jam.

Solution: If the rollers are jammed, they will need to be repaired or replaced. If the return rollers are dirty, rubber return discs must be fitted. Make sure that the belt wipers are working properly. Retain/replace belt scrapers where necessary.

Possible cause: The belt may be dragging spilled material.

Solution: Improve cleaning and maintenance procedures.

Possible cause: Poor loading conditions (e.g. side loading).

Solution: Improve ducts and hoppers.

Possible cause: The cover may be of low tensile strength.

Solution: When replacing, use a higher quality and possibly heavier cover.

Possible cause: There may be excessive sag between idlers caused by load changes. Belt tension may be too loose.

Solution: Adjust the pulleys to retain the belt.

Find out how to solve the main problems with industrial conveyor belts: causes and prevention.

 

Be productive with rubber conveyor belt problems

Any anomaly observed in a rubber conveyor belt or in a rubber conveyor belt must be addressed immediately to prevent further damage or failure. If the source of the problem is not clear, it is recommended to consult a qualified service expert.

The routine inspection of a rubber conveyor belt, allows problems to be detected before they become serious. Therefore, hiring a service technician to carry out regular inspections of conveyor belts will also help to detect any potential problems early. The frequency of recommended inspections varies depending on the operation, and may be a couple of times a year or even monthly in particularly demanding cases.

Both inspections and maintenance are essential to ensure that your equipment performs well and increases its service life. Here are 7 questions to ask yourself to optimise your production equipment inspection programme. https://tecnologiaparalaindustria.com/7-questions-you-must-consider-optimising- the-inspection-programme-production-equipment/

 

Conclusions on rubber conveyor belts

Bulk material handling equipment in any operation is critical to maintaining uptime and process efficiency. Problems with a rubber conveyor belt often manifest themselves as belt anomalies and determining the possible cause and solution can be a major problem. That is why we insist on the importance of early detection of problems to avoid unnecessary downtime and production losses.

Discover how in-plant material handling automation improves the supply chain.