CAN you overtighten wirecloth?

General answer is no.......we want wirecloth to be what we call DRUM HEAD TIGHT. over the CAMBERED rubber covered support rails.

If we RIP the cloth along the length of the support rails.....this indicates the wirecloth is LOOSE or NOT TIGHT ENOUGH.

Think of a bobby bin (hair) bend back and forth once or twice and it breaks.......same thing applies if wirecloth is allowed to be too loose......it moves up and down and BREAKS from abuse.

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The wirecloth must be tight enough to "SING" when tapped with a hammer so the wirecloth is tight enough to VIBRATE as one in unison with the vibrating body of the vibrating screen. If it is allowed to run at its own frequency ......it will typically break.

TORQUE VALUES are dubious here........drum head tight is the key.....very tight.

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Make sure your support rails are in good shape ...not warped or puckered to ensure even tension along length of the wirecloth section.

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Make sure you retighten your nuts after first shift.........as wirecloth slackens up after first shift......becomes a tad loose or sleazy.....and it will contribute to eary failure

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Make sure your rubber on the support rails is all GOOD....and none missing.....steel on steel equals BREAKING or RIPPED wirecloth

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Make sure your wirecloth sections are NOT TOO WIDE......if they bottom out on the siderails before stretched......the wirecloth can NOT BE TIGHTEN.....and will break

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Make sure your steel longitudinal rails have a even CAMBER across the width of the screen. We DO NOT want the wirecloth to be tighten down on one rail and sitting with a space between the underside of the wirecloth and the rubber strip it should be tightened down on.

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Make sure the bend of the metal reinforced edge is correct and it fully engages the tension rail and that the piece of wirecloth is NOT being held up in the air at the sideplate. This will cause the cloth to tear if improper manufactured design.

HOPE THIS HELPS..........

enjoy...........Cheers.....George Baker - MODERATOR ■

Hello Keiths,

Mr. George Baker has given a very good reply and information.

The other cause of failure could be the overloading of screen. The overload can arise due to overfeeding as well as poor screening.

If there is overfeeding, there would be more mass of material on the deck and consequent more stresses and failure.

Similar situation can also arise if there is lesser screening whereby thicker layer of material will remain present on the deck till its discharge end. This is also synonymous to overfeeding and overstressing. This situation can arise due to change in characteristics of material or due to under-designing of screen etc.

Also check the quality of welding and the precautions / annealing etc. necessary in welded joints in screen.

So, I suggest you can check as suggested by Mr. Baker and then also check the rate of feeding and quality of screening etc.

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 ■