Sdas,

since you have stated that it is a new rubber belt but not

whether it is on the carry or return side or whether it is in service

It looks exactly like a conveyor belt that was not cured properly

when it was woven/glued/pressed/ assembled at the "master

slitter" assuming that the master slitter was where it was

manufactured. ■

Is this in the top cover or bottom cover?

First thought is that the very surface of the cover is unable to contract after becoming stretched as it passes around the drums. Could be that the compound on the surface is a little different than that underneath, or its coming into contact with something that is prematurely aging the very top surface of the belt. I've seen it often with cracks in the very top layer of the cover, normally with heat resistant belt, but this seems like the exact opposite, where the top part has actually stretched more and is unable to return to it's normal shape.

Is the belt, by any chance, a PVC solid woven belt with a synthetic rubber cover, mostly found in underground mining?

How thick are the covers? ■

Dear Shri Das,

I am not clear from the query whether you are seeing the surface marks on a brand new belt or on the belt after some use in plant.

If such marks are on brand new belt, then it is a manufacturing defect.

However, if such marks have appeared after some use of belt then better you inform about the application main features, such as material being handled, lump size, temperature, belt speed, width, belt cover grade, type of carcass. This information will help the respondents to look for some reason and possibly to make some suggestions.

Regards,

Ishwar G Mulani.

Author of Book : Engineering Science and Application Design for Belt Conveyors.

Author of Book : Belt Feeder Design and Hopper Bin Silo

Advisor / Consultant for Bulk Material Handling System & Issues.

Email : parimul@pn2.vsnl.net.in

Tel.: 0091 (0)20 25882916 ■

Do these cracks appear to follow a steel cord pattern? I anticipate they are on the bottom cover. I have seen many belts with similar cracks. There are a range of conditions that can create such a pattern.

The cracks typically are not deep and will not grow much deeper with age.

There is no corrective action if it is a poor cure or is ozone induced short of replacement.

If they are longitudinal, as I guess, they are tensile failures in the tranverse direction or across the width. If so, then you must ask, how can a tensile failure occur across the width. Shrinkage, or impairment of the rubber such as an ozone or surface hardening action during curing.

If the cracks are on the bottom cover, try to bend the belt to see the depth. I expect the depth is no more than 1.5 mm. Observe the cracks in the region of the wing-to-center roll bend zone. If the crack depth is no greater in this area, then you should have no worries for the moment.

All this is all conjecture, since you provide little information on the details, which are many. ■

If the cracks are longitudinal, observe the cracks seem to be uniform across the width even out to the edge where there is little stress from any working action.

Again, no data to make a more definitive observation. I could be off by miles. ■

The reason on the manufacturing process may be as follows:

1> There may be cross reinforce steel breaker, and the breaker is not very good handled when processing with the belt.

2> The rubber are not vulcanized perfectly(may becasue the vulcanizing time is not enough long), and when passing the drum, the pleats are formed out.

3> The raw material is not good,reclaimed rubber compound is too much in the total mixing of rubber.

The reasons above is the possible resons in the manufacturing procudure.

Best regards,

Yung

Sales Director

SALES DIRECTOR

--------------------------------------------------------------------------------

Qingdao Huaxia Rubber Industry Co,.Ltd

Zhengyang Road Chengyang District

Qingdao City China

Tel:86-532-82519300

Fax:86-532-82519238

E-mail:belt@huaxiarubber.com

Website:www.huaxiarubber.com

-------------------------------------------------------------------------------- ■

Hi SD,

I have come across similar defects from manufacturing and service related operations (but will not commit an answer). Would you advise the belt specifications, manufacturing method and age (date of manufacture and date of service)?

These details will assist our learned friends in identifying probable cause and provide some answers and possible rectifications.

Kind regards,

Peter Thorpe

peter.thorpe@rescan.com.au ■

Hi SD,

Could you measure the depth of these marks? (you have mentioned a pulley cover thickness of 1.6mm) as well as providing the above requested hardness within the areas of interest and hardness of the general belting.

Kind regards, ■

deffective belt send it back to the suppliers the bonding between the carcass is not right most probbably the carcass was not treated before it was molded with the rubber it will not show on the top cover because of the rubber thikness difference ■

Dear Sdas,

Already asked your belt furnisher?

If yes, could you please forward the answer to this forum?

Thanks

Alexandre ■

the original post is almost 3 years old I am sure he has it corrected by now.

thread closed. ■