Wear note
Screen tension discipline
Loose decks destroy media and pretend the crusher is the problem.
By Mr Thabo Molefe, Parts manager
Thabo Molefe manages all parts operations at Crusher Consumables’ Sunnyrock yard, making sure the right crusher and screen spares reach the right place at the right time.
AuthorWhy this matters on the plant
Too often I am called to a site where screens are blamed for poor throughput or odd crusher wear, only to find that loose decks and slack screen media are the root cause. In South African conditions, where dust, heat and vibration are constant companions, tension discipline on your screen deck is not a nice-to-have, it is a must.
The cost of a loose screen deck
When screen tension is not properly maintained, the screen media will flex excessively with each pass of material, causing rapid wear along the edges and at the bolt holes. We have seen plants in Limpopo and the Karoo lose two or three sets of wire mesh in a month simply because the side tension rails were finger-tight, not torqued. This not only wastes screen panels but also means more downtime and extra weld repairs to the deck frame.
Loose deck panels rattle and vibrate out of sync, which creates a ripple effect through the screen box. Besides shredding screen mats, this can shake cheek plates loose and cause feed spillage, leading the team to think there is a crusher issue when it is actually just poor screen discipline.
Proper tensioning technique
Screen media, whether wire or polyurethane, depends on firm, even tension across the full width of the deck. For most South African quarry and sand plants, this means checking side tension bolts at least once a week, and daily if you run double or triple shifts.
Always use a torque wrench set to the OEM specification. Never guess by hand. Tighten opposite pairs step by step, not one side at a time, so that the clamp bar applies pressure evenly. Uneven tension is as bad as loose tension, creating stress points where cracks and premature tears appear. After fitting new media, run the screen empty for five minutes and recheck tension once it has bedded in.
- Clean the rail and clamp area before fitting new media.
- Use only OEM or approved high-tensile tension bolts.
- Replace any rounded or stretched bolts immediately.
- Check for missing or worn clamp bars during tensioning.
- Tag tensioned areas with paint for quick weekly inspection.
Common mistakes we see on South African plants
One classic error is mixing old and new media side by side. This leads to uneven stretching, as the old panel sags more, making the new one work harder and fail early. Another is letting sand or grit build up between the media and the clamp rail, which prevents proper contact and leads to 'walking' of the screen mat. In the humid Durban coast or the dust storms of the Highveld, grit build-up is relentless, so regular cleaning is non-negotiable.
We also see operators over-tighten, thinking tighter is better, but this bends the clamp rail and crushes the ends of wire mesh, making it break at the edge. Always defer to the torque value in your manual. Finally, skipping inspection of cheek plates is risky. Loose plates let material bypass the screen, causing rapid wear and, in some cases, damaging the frame.
Discipline means planned downtime, not unplanned chaos
A disciplined screen tension programme pays off in fewer Eskom power cut-related stops, because you plan your checks around available supply. We recommend scheduling tension and cheek plate checks as part of your standard shutdown routine, whether on Sundays or during midsummer storms in Cape Town when production must pause anyway.
Keeping spare sets of clamp rails, cheek plates and tension bolts in your parts container saves a mad bakkie dash to Joburg or Durban just to get production running again. Our parts yard in Germiston stocks these for quick collection or dispatch. For advice or supply, you can reach us through our contact form.
Related parts: Cheek Plate Pair. You can also browse all parts and plant guides.
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