Maintenance personnel and managers need to be in agreement as they consider various factors impacting the timing and necessity of conveyor belt repair.
It’s imperative that companies develop and communicate repair and replacement policies. These policies should not be too rigid, for example:
Always repair a damaged or worn belt
Always discard a damaged or worn belt
Always replace a belt when its turns X years old regardless of its condition
The problem term in the above examples is “always”, which may result in unnecessary waste.
5 Considerations to Make Before a Belt Repair
Consideration #1: How extensive is the damage?
A minor tear may pose little risk of spillage or snagging or enlargement and can be repaired at a scheduled down time.
Edge fraying or cover scoring, may be present yet not pose a hazard. This issue can also be repaired at a scheduled down time.
Rips cause loss of strength. Tension forces normally carried by the damaged area are transferred to the adjacent section of the belt. If the width of the rip is large enough, the overstressed balance of the belt will most likely fail.
A common rule of thumb- if no more than 25% of the belt width is involved, a repair is practical; when more than 25% of the width is damaged, a full re-splice or saddle section insertion is preferable.
Consideration #2: Is replacement a better option?
One important factor in the repair decision is belt size.
Replacement means the immediate or near term availability of a spare belt. Change out time for a smaller belt is often less than for a major repair. Under these circumstances, replacement is recommended.
If a spare belt is unavailable, the time element in securing one versus the estimated repair time (assuming the present belt can be repaired) must be considered.
Belt replacement will be necessary is there are major areas of ripping and tearing. Another factor to consider is whether the belt is a good candidate for off the conveyor repairs.
Will continuing to use the belt to provide more production reduce its reparability?
Consideration #3: Is a temporary repair an option?
There is a time and place for improvised or temporary belt repairs—many have proved successful in maintaining at least partial material flow until other arrangements can be made.
On the other hand, an ill-conceived repair is just a waste of valuable time.
The most vital question in considering temporary belt repairs:
Can the tensile strength of the belt be restored or bridged sufficiently at the point of injury to withstand the drive and take-up forces?
If the nature of the damage will not permit this with some assurance of success, the belt should be completely re-spliced or have a repair section (saddle) spliced in at the point of injury.
Temporary repairs of the type referred to above would include some form of mending with metal fasteners or a scab overlay held in place with fasteners or elevator bolts.
Such temporary repairs are usually employed in conjunction with a reduction of the belt feed rate to lessen effective belt tension. Major carcass damages over extensive areas of the belt would greatly limit the feasibility of temporary belt repairs. Replacement of all or major sections of the belt a preferable remedy.
Consideration #4: If a repair is preferable, what techniques should be used?
In most cases belt repairs will be one of three types:
– metal fasteners
– cold cure
Consideration #5: How much time is available?
If you can’t divert material or product to an adjacent conveyor, then time is of the essence.
Time factors include the need to complete a production run or a work shift, or the loading/unloading of a container. In each instance, the interruption of operations will bring up the same questions: repair or replace the belt?
Depending on specific circumstances, a major rescheduling of operations may be the only choice.