Filter Cloth Edge Wear: Causes and Cloth-Side Fixes
The belt frays, frills or tears at the edge while the middle of the cloth is still doing its job. Before you scrap a serviceable belt, find out what the edge is rubbing against.
On a rubber-belt horizontal vacuum belt filter the edge of the cloth is the highest-stress strip on the whole belt, and it is the only part that is doing three jobs at once. It runs against the vacuum box sealing strips, which is where the vacuum is held; it is the part that reaches the edge guides and the roller ends whenever the belt moves off-line; and it is a boundary in the fabric itself, where yarns end instead of continuing. The body of the cloth is supported, covered by cake and protected on both faces. The edge is none of those things.
Read this page together with belt tracking. Edge damage and tracking are the same story told from two ends: a belt that wanders puts its edge into things that were never meant to touch it, and an edge that has lost its treatment and its width no longer gives the machine a straight reference to steer by. Whichever came first, you will end up diagnosing both.
Does this match what you are seeing?
- The outer strip of the cloth is frayed, frilled or feathered while the centre of the belt still filters normally.
- Loose yarn ends hang off the edge and wrap themselves around a roll or collect in the wash box.
- A tear has started at the edge and is running inwards, across the direction of travel.
- The belt has visibly lost width — the edge no longer reaches the reference it sat at when it was fitted.
- Slurry or filtrate escapes past the edge onto the carrier belt, the drip pan or the floor.
- One edge is glazed, hardened or heat-marked along a continuous line.
If that is not quite it
The belt wanders off-line and the edges look like a consequence Belt Tracking
The damage starts at the joint and runs along it, not along the edge Joint / Seam Failure
The edges are sound and the body of the cloth has closed up Cloth Blinding
Cloth, machine, process
Edge wear is the failure mode where the machine column matters most, because the edge is the part of the cloth that touches the machine. Two of these three columns are not ours to fix.
- The edge is a cut edge with no treatment, or the treatment has failed. A woven fabric that is cut across its width ends in free yarn ends, and once one of them is broken the rest have nothing holding them.
- The belt was built wider than the machine actually takes, so the edge is in permanent contact with a guide or the frame instead of only touching it during a correction.
- Elongation is uneven across the width, so one edge carries more tension and reaches its contact point first.
- The edge treatment adds thickness, and that thickness sits where the vacuum box sealing strip runs — so the treatment that protects the edge is also the thing being worn.
- Vacuum box sealing strips worn, hardened, displaced or standing proud, so they cut a line along the cloth instead of sliding under it.
- Sealing strips running dry. On a rubber-belt horizontal vacuum belt filter the strips are normally lubricated by water; a dry contact wears and heats.
- Edge guides or roller ends with a damaged, sharp or scaled contact face.
- The rubber carrier belt itself is damaged, curled or tracking off, leaving the cloth edge unsupported or presenting an edge of its own for the cloth to ride on.
- Something fixed on the machine — a drip pan lip, a wash box side, a frame member — that the belt can reach whenever it drifts.
A new cloth will not fix these. It will wear the same way.
- Feed spread to the full width, so slurry runs over the edge and abrades the cloth from underneath as well as from above.
- Abrasive solids collecting in the edge region of the vacuum box, where there is no cake to protect the fabric.
- Wash sprays reaching past the cake edge. Unprotected fabric under a jet wears quickly; fabric under cake does not.
- Scale or packed solids building up at the ends of a roll, in gypsum-type duties in particular.
Correct these first, or the new belt inherits the fault.
The cloth form for this machine family is Endless belt, clipper / PAD, edge seal — the edge seal is part of the specification, not an accessory. Machine families and what has to be confirmed per machine: HVBF compatibility. Duties where roll and edge build-up is part of daily life: phosphogypsum filtration and FGD gypsum dewatering — two separate duties, not one.
Work through it in order
Every step says what to look at, what to measure and what to photograph. The point of the first two steps is to stop treating the wear as something the cloth is doing to itself.
- 00
Stop and isolate first
- Look at
- Machine stopped, isolated and tagged out before anyone reaches towards an edge, a roll end or a vacuum box.
- 01
One edge or both?
- Look at
- Whether the damage is on one side only, or symmetrical on both.
- Measure
- Depth of damage inwards from the edge, on each side.
- Photograph
- Both edges at the same point on the belt, labelled left and right as you face the discharge end.
One edge points at steering, alignment and contact on that side. Both edges point at something that acts across the whole width — box geometry, sealing strips, or a belt built to the wrong width.
- 02
Find where the damage is being made
- Look at
- Mark one point on the cloth edge and follow it around the loop. Where is the edge actually in contact with something?
- Photograph
- The contact point itself, with enough of the surroundings in frame to identify it.
Wear appears everywhere along the belt because the belt moves. It is made in one or two places, and those places are on the machine.
- 03
Inspect the vacuum box sealing strips
- Look at
- Along the whole length: wear, hardening, steps between sections, strips standing proud of the box face, missing lubrication water.
- Measure
- Whether the strip height is consistent end to end, by whatever method your site normally uses.
- Photograph
- The strips along their length, plus a close shot of any step or high spot you find.
- 04
Check the edge guides and roller ends
- Look at
- Sharp corners, worn grooves, scale, weld spatter, anything that has become a cutting edge.
- Measure
- Clearance between the cloth edge and each fixed part it passes.
- Photograph
- Each guide and roll end, before you clean or dress anything.
- 05
Check the rubber carrier belt edge
- Look at
- Whether the carrier belt supports the cloth right out to the cloth edge, and whether the carrier belt edge is itself damaged or curled.
- Measure
- Overhang of the cloth beyond the carrier belt, on each side.
- Photograph
- Cloth, carrier belt and frame in one shot so the relative positions are readable.
- 06
Read the edge of the cloth itself
- Look at
- What kind of edge it is — cut, fused, folded, taped, corded — and what has failed about it: the treatment lifted, the treatment worn through, or the fabric torn behind an intact treatment.
- Photograph
- Close-up of the edge on both faces. This is the single most useful photograph on this page.
- 07
Measure the width in several places
- Look at
- Whether the belt still holds its width all the way round the loop.
- Measure
- Cloth width at four or five points around the loop, and the width it was supplied at if you have the paperwork.
- Photograph
- A tape across the cloth at the narrowest point you find.
- 08
Copy the nameplate and record the pattern
- Look at
- Machine brand, model and serial number. Then write down when the edge damage appeared, whether it followed a tracking incident, and whether it followed work on the machine.
- Photograph
- The nameplate, lit from an angle so the flash does not wash it out.
Not sure how to measure the belt itself? See the measuring guide.
Edge treatment is a line on the specification, not a shop detail
A belt ordered by width, length and seam alone leaves the edge to whoever cuts it. That is how a plant ends up replacing the same edge twice. The treatment types below are the ones used in industrial filter fabric practice generally — they are industry knowledge, not a list of what we can supply, which is the table underneath.
Sealed / fused edge
The cut edge of a thermoplastic fabric is fused so the yarn ends are bonded together and cannot unravel. Adds little width. How well it survives depends on what the edge rubs against.
Woven selvedge
The edge is formed as the fabric is made rather than cut, so there are no free yarn ends at all. Only available where the fabric width and the finished belt width line up.
Folded or hemmed edge
The edge is turned back and secured, putting two thicknesses where one was. Robust, but the added thickness sits exactly where the sealing strip runs.
Edge tape or reinforcing strip
A separate strip is applied over the cut edge. The failure mode moves: instead of the fabric fraying, the question becomes whether the strip stays attached.
Edge cord or bead
A raised edge gives a guide something positive to run against, which couples the edge decision directly to the tracking arrangement on the machine.
No edge treatment survives a sharp machine
A sealing strip standing proud, a roller end with a burr, a curled carrier belt edge — these will wear through a fused edge, lift a tape and cut behind a fold. Specifying a heavier edge on a machine that has a contact problem buys you a slower version of the same failure, on a belt you have already paid for. Dress the machine first, then decide the edge.
Tell us your machine and what the edge is rubbing against, and we will say honestly whether we can help.
Which of these we can actually supply
Our own confirmed manufacturing range is not published yet. Rather than print a number we cannot stand behind, the table below is a to-be-confirmed list. Send your case and we will come back with what the factory has confirmed in writing for your dimensions and your duty.
| Edge-side option | What it addresses | Confirmed range |
|---|---|---|
| Edge treatments that can be supplied | Whether the edge unravels once it is damaged | UNKNOWN — pending factory confirmation |
| Thickness added at the edge by each treatment | Contact with the vacuum box sealing strip | UNKNOWN — pending factory confirmation |
| Which treatments suit which polymer and construction | Whether the treatment survives the duty chemistry | UNKNOWN — pending factory confirmation |
| Width tolerance and dimensional stability at the edge | Whether the belt holds its width in service | UNKNOWN — pending factory confirmation |
| Maximum fabricated width | Whether your machine is inside range at all | UNKNOWN — pending factory confirmation |
| Whether an existing belt can be re-edged | Repair versus replacement on a belt with a sound body | UNKNOWN — pending factory confirmation |
Width is the other half of the edge decision, and it is measured off the old belt rather than taken from an old order: how to measure your old belt. Process detail on how belts are put together: factory and quality control.
How to photograph an edge failure so it can be read
An edge photograph has to answer one question: were the yarns cut, worn, melted or pulled? Those are four different faults with four different owners, and a badly lit close-up settles none of them. Six rules.
-
Light it from the side, not from the front
A direct flash flattens a frayed edge into a white smear. Light coming across the edge throws the loose yarn ends into relief and shows whether the ends are square-cut, worn round, or beaded from heat.
-
Put a rule in the frame
A tape or steel rule laid across the edge, at right angles to it, turns "badly frayed" into a readable depth. Without it every edge photograph looks the same size.
-
Both faces, same spot
The face that ran against the sealing strip and the face that carried the cake wear differently. One photograph of one face is half the evidence.
-
Both edges, even though only one failed
The undamaged edge is the reference. It shows what the treatment looked like when it was new, which is often the only record of what was originally supplied.
-
One wide shot for position
Step back and take the damaged edge together with the vacuum box, the edge guide and the frame in one frame. This is the photograph that shows what the edge was touching — and it is the one that is almost always missing.
-
Photograph the machine, not only the cloth
The sealing strip along its length, the roller end, the carrier belt edge. Do not clean or dress anything first. Scale, a burr or a step in the strip is evidence, and it disappears the moment someone tidies up.
Label every shot left or right as you face the discharge end, and keep that convention. The photo checklist on the measuring guide covers the rest of the set: photo checklist.
Replace it, or fix the filter first?
- A tear that has run from the edge into the body of the cloth.
- Fraying deep enough that the damage has reached the cake area rather than the margin outside it.
- Width lost permanently — the belt no longer tracks true even after the machine checks out.
- Edge damage together with slurry escaping past the edge, because the loss of filtrate and the loss of vacuum compound each other.
- An edge treatment that has lifted along a long run and cannot be made good in place.
- The damage is cosmetic fraying at the extreme edge, outside the cake width, and it is not progressing.
- A contact point has been found on the machine and dressed, and the edge has stopped getting worse.
- The sealing strips have been replaced or re-set and the wear line has stopped deepening.
- The edge wear followed a single tracking incident that has since been corrected.
The awkward case is the belt with a sound body and a ruined edge. It is a real loss of a serviceable asset, and it is worth spending an hour finding the contact point before you order, because the replacement belt will meet the same contact point on its first shift. We do not publish expected service life in months — it depends entirely on your duty and the condition of your machine.
Decided it needs replacing? Next step is measuring the old belt →
The same facts, whether you ask us to diagnose or to quote
Tick these off as you collect them. Nothing here is stored or sent from this page — it is a scratch list for your own use.
Where edge problems lead next
Belt Tracking
The other half of the same story: a belt that wanders damages its edges, and damaged edges make a belt wander.
Joint / Seam Failure
Damage that starts at the joint rather than at the edge, and why the two get confused on a belt that has both.
Horizontal Vacuum Belt Filter Cloth
Endless belts built to your machine dimensions, where edge treatment is one of the lines on the specification.
All eight failure patterns, split the same way: filter cloth problems.
Questions about edge wear
Can a worn edge be repaired instead of replacing the belt?
Sometimes, and it depends on what failed. A treatment that has lifted over a short run is a different problem from fabric that has torn inwards, and a repair on a belt whose body is sound is worth considering. What we cannot tell you from a web page is whether your particular edge is repairable — send the close-up of the edge on both faces and we will say what we think, including if the answer is that it is not worth it.
Is edge wear a cloth fault or a machine fault?
The edge is where the cloth meets the machine, so it is usually both. An untreated or failed edge is cloth-side. A proud sealing strip, a sharp roller end or a carrier belt that has curled is machine-side, and a new belt will wear against it exactly the same way. Work through the checks before you order, because the lower-cost outcome here can be a sealing strip replacement rather than a belt.
Which edge treatment should I specify?
That decision belongs to your machine, not to a catalogue. The treatment has to survive your duty chemistry, and it has to fit where your sealing strips run — a thicker edge that protects the fabric can also be the thing that gets worn, and a corded edge changes how the belt is guided. Tell us the machine, the strips and the duty, and it gets fixed in writing during the engineering review.
How long should the edges last?
We do not publish a service-life figure. Edge life depends on the slurry, the condition of the sealing strips and guides, and how often the belt is allowed to run off-line. Anyone quoting you a number of months without asking what the edge rubs against is guessing.
These answers are engineering judgement, not measured results, and no FAQ structured data is published from this page until they have been verified by our technical staff.
Measure your old belt and send it to us
Width at its narrowest point, length, seam type, the edge photographs from the section above, and the nameplate. That is enough for an engineering answer instead of a guess. No account, no registration.
Replacement cloth fabricated to your machine dimensions. Not an OEM spare part.