Shane,

The answer is no, in fact the opposite should be true. We sometimes do this because there has been a problem during manufacturing and this is a way of counteracting the induced tracking problem. This is also true if the fabric belt has been slit to width. I think you need to look elsewhere for the cause of this problem, for instance how were the belts stored before installation, splicing etc.

Col Benjamin ■

Belt conveyor storage and handling is crucial to the success of the belt performing correctly after installation.

1. The belt should be stored on a support stand to prevent the total weight of the roll resting in one spot.

2. Should be stored inside a covered area.

3. Cover roll with dark plastic or tarp.

4. Randomly rotate roll every 90 days.

5. Use spreader bar when lifting.

A condition called camber (banana curve of the belt) can be the result of incorrect storage. Often confused with crooked splice.

For addtional information see chapter 2 Foundations III by Martin Engineering ■

Shane,

It can matter with steel cord belts given the cable lay ups and edge rubber width but generally it does not matter with fabric belts as the low elastic modulus of the carcass allows for any issues to be quickly aligned once tension is applied.

Col Benjamin ■

Have you ever been to a belt production plant?

The operator has better access on one side like with press controls, air hoses, spray equipment, lighting direction for inspection, equipment table for all stencils, etc,. ■

Shane,

There is no logical reason for this other than it could be a hang over from recommendations made by steel cord belt manufacturers. Ask Apex to explain and share their answer with us

Col Benjamin ■

Hi Shane

Steel or Fabric ? ■

Hi Shane,

Like you, I've noticed this pnenomenum with fabric belts. Although it has been suggested by others that mixing the belt directions should help, not exacerbate the belt training problem, experience suggests that it does matter.

Surprisingly, I have not noticed this with steel cord belt installations - this could be due to luck on my part or the greater care taken with steel cord belt installations.

With those few cases where I've noted this with fabric carcass belts and have been able to investigate, I've been able to trace the problem to spotty tension inconsistances with the carcass across the width of the belt (i.e. the belts checked had carcass waves on one side, but not uniformly.

Suffice it to say, it is a good practice to keep install belts uniformily (all stamps on one side) and in the reverse order they were produced in (if possible). This minimizes installation variables and places any mistraining problems on the splicing or belt manufacturing processes (assuming loading, idler alignment, pulley alignment, skirting, et cetera are in order).

Regards, ■

I think this has been done to death but there is absolutely no reason from a manufacturing point of view unless the belt has been slit from a wider width either prior to curing or after. It also does not matter if the belt has cut or capped edges. If this is the observation then I would presume it has been used as an excuse to cover a poor belt splice or clipped joint or the belt may have been stored incorrectly or there were surface or fabric imperfections that needed time to be worked away by the system. A full and correct cycling analysis when the belt was tracking poorly would tell the root cause of why there were problems and this is what should have been done before someone went to the expense of reversing the belt as I would have been looking to the installer or belt supplier to fix the problem at no cost to me.

Colin Benjamin ■

The issue is not related to branding or where brands or roll numbers are placed. The issue is tied to the way the bulk roll (mother roll) was manufactured. What likely occurred is that the belt was made at a much wider width and then slit to suit the needs of the applications (72" roll, slit to 2 x36"). When this occurs, it is imperative that the factory edges (two outside edges) are matched during installation. This is standard on slit to order belting - not made to width belting. If you are seeing brands on opposite edges of two separate pieces, this is what likely occurred. One of two things happened:

1) The factory did not know that the belts were going out to be installed on one system (or did and made an oversight error).

2) The distributor, OEM, service company did not specify upon order or too made an oversight error upon supply.

The reasoning behind matched edges are simple. It relates to carcass tensioning across the width of a belt. Because fabric belting is a textile based product, there will be tension variations across the width. Typically in larger width rolls or slabs, the edges have the most uniform tensions. Therefore, when slitting such a roll for installation on a single conveyor system, it make the most sense and is best practice to match the factory edges. At that point, if you can contain the tracking signature to one side, it then can be tracked to the center.

Hope this is a helpful explanation. ■

Most odd indeed, but did you give the belt time to bed-in and get a bit of permanent stretch?

You mentioned that the belting is synthetic ply, so this should happen (but does nothing for a crooked splice though)

Cheers

Taggart LSL Tekpro ■

Originally Posted by Graham Spriggs

Most odd indeed, but did you give the belt time to bed-in and get a bit of permanent stretch?

You mentioned that the belting is synthetic ply, so this should happen (but does nothing for a crooked splice though)

Cheers

Taggart LSL Tekpro

Dear Mr.Graham Spriggs,

What is the meaning of "bed-in" ? How many hours/days would it take to do so ?

Thanks & Regards, ■

Originally Posted by sganesh

Dear Mr.Graham Spriggs,

What is the meaning of "bed-in" ? How many hours/days would it take to do so ?

Thanks & Regards,

Bed-In = Break-In. With fabric carcass belting, there is a period of break-in that basically equates to stretch - both longitudinally and transversely. Each period of stretch, or relaxation is affected by the longitudinal torque as transferred to the belt from drive through normal operation and the transverse relaxation as affected by loading (based on material types, temps, tonnages, cycle time). In most fabric carcass belting, a two-week period of full operation is generally accepted as the break-in period. In this period, the permanent stretch is usually realized. This, "beak-in" period can also be affected by the degree of system operation, any changes in tonnage and belt speed, carcass modulus and the system required tensions vs. the belt tension relationship. Hope this is helpful..... ■

Thank you very much Mr.Buddy Wilson.

Though longitudinal stretch may make the width of the conveyor reduced, visible reduction could not be found.

In the line of your reply, I think that the conveyors having variable speed drive may take more days for "break-in" compared to DOL start ( Direct On Line ) conveyors.

I was told that for complete permanent stretch of conveyors, they may take three months, though I do not have any written information.

Lots of regards, ■

Originally Posted by sganesh

Thank you very much Mr.Buddy Wilson.

Though longitudinal stretch may make the width of the conveyor reduced, visible reduction could not be found.

In the line of your reply, I think that the conveyors having variable speed drive may take more days for "break-in" compared to DOL start ( Direct On Line ) conveyors.

I was told that for complete permanent stretch of conveyors, they may take three months, though I do not have any written information.

Lots of regards,

Sir -

You should not see any visible sign of narrowing in the belt. If there is a conspicuous or blatantly obvious narrowing of the belt, you have bigger troubles on your hands. The belt should only relax, and not have any dramatic changes in geometry. The belt should exhaust its permanent stretch prior to 3 months, although your point is well taken in regard to the VSD. However, if the belt is running under normal loads and at a slowed belt speed, permanent stretch should be realized faster. ■

Hi Shane,

What strength fabric belt are you talking about?

Best regards,

Andrew ■