Dear Shri N Kathiravan,

You have mentioned that recently you are facing more frequent failure of belt joints in 2400 mm wide belt shiftable conveying system. So, this is occurring after what service life?

The belt joints can fail by any one or more number of reasons mentioned by you. It would be difficult for the forum respondent to comment as to which could be the cause.

The practical suggestion is that you can use vulcanising solutions as recommended by belt manufacturers, and assign the vulcanising responsibility to the belt manufacturer or do vulcanising under their supervision, as per their rules, for your convenient time frame. Then, see the results. I am making the above suggestion as a test case and not as a permanent feature in your activity.

In general, the belt is supposed to give specific strength at joint when vulcanized as recommended by belt manufacturer (supplier), using the compounds compatible to their belt. The joint so made should also have certain life.

The other reasons could be as follows:

1) Pulley diameters are not of required size. This should also include excessive snubbing by small deflector pulley.

2) Improper or short transition length i.e. flat to trough or trough to flat should be as per specific calculations so that there is uniform / gradual strain in transition length

3) Impact strain at loading point is excessive i.e. too great a fall or high velocity of impact.

4) Convex radius is sharp.

5) Belt tension during steady state, starting and braking is exceeding the design limits. This could be due to:

a) You are making conveyor longer than the design limit.

b) Actual starting factor is more than the design limitation.

c) Actual braking factor is more than the design limitation.

d) Excessive misalignment of modules, which could increase conveying friction coefficient or drag.

e) Excessive idle tension by take-up or malfunction of take-up controls. The best course is to measure belt tensions at critical points in belt conveyor and see whether you are exceeding the belt tension limits in actual operation.

So, if the belt tension happens to be within limits then you will be able to narrow down the reason either due to belt or due to serial number 1, 2, 3 and 4. For the reason 1, 2, 3 and 4 the verifications can be done very easily.

Trust the information will be of use to you.

Regards,

Ishwar G Mulani.

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

Advisor / Consultant for Bulk Material Handling System & Issues.

Email : parimul@pn2.vsnl.net.in

Tel.: 0091 (0)20 25882916 ■