Chute liners: how transfer chutes wear, liner materials and where each belongs, laying out liners, and planning changes from measured wear
Chute liners from the maintenance side: impact and sliding wear and where each happens in a transfer chute, abrasion resistant plate, chromium carbide overlay, ceramic, rubber, polyurethane and low friction liners compared, laying liners so the flow steps over every joint, the failures that cost most, and a measured wear program that plans liner changes into shutdowns. With a hood and spoon liner layout and wear trend.
Key takeaways
- Chutes wear in two ways: impact where the stream lands, and sliding abrasion where it runs along the liner. Each zone needs a different liner.
- No liner material is best everywhere. Hard materials resist sliding but crack under impact, and soft ones absorb impact but cut under sliding.
- Lay liners so the flow steps down over each joint, never into an edge.
- Number every liner on a drawing, measure its thickness at marked points, and trend the readings. Liner changes then go into a planned shutdown, not a breakdown.
- A liner falling onto the belt is the costliest liner failure. Fasteners and backing need as much attention as the wear face.
A transfer chute has its liners changed every shutdown whether they need it or not, except one plate on the spoon that wears through in eight weeks. Between shutdowns, a hole opens behind it, ore pours through the chute shell, and the conveyor stops. The other liners, still half their thickness, come out with it.
This guide covers chute liners from the maintenance side: how chutes wear, the liner materials and where each one belongs, laying liners out, the problems that cost the most, and a measured wear program that plans changes. It sits beside the guides to DEM modelling for transfer chutes, crusher maintenance and liners and conveyor belt tracking. The drawing is schematic.
How chutes wear
Wear is concentrated where the stream lands and where it slides fastest. On a hood and spoon chute the hood takes a glancing impact from the trajectory, then the stream slides down the hood into the spoon, which turns it onto the receiving belt. Each of those positions wears differently, at a different rate, and benefits from a different liner.
| Wear | Where it happens | What it does |
|---|---|---|
| Impact | The stream strikes a surface at a steep angle, often where it leaves the head pulley | Gouging and deformation, cracks and chips in brittle liners |
| Sliding abrasion | Material slides along a surface under its own weight | Polished, grooved and thinned plate, fastest where the flow is fast and heavy |
| Impact and sliding together | The stream lands then slides, as on a spoon or a curved plate | The worst wear at the landing zone, then a long wear path below it |
| Corrosion assisted wear | Wet or acidic material removes the protective surface as it wears | Faster wear on plain steel in wet service |
| Build up | Fines stick to the liner and grow until the chute blocks | Not wear, but the reason liner friction and shape matter |
Liner materials
Choosing liners is a trade between hardness, which resists sliding, and toughness, which survives impact, with friction and weight to consider too. Low friction keeps sticky material moving, and lighter liners are quicker to change. A material that works on one chute may fail on another with a bigger lump size, a higher drop or wetter ore.
| Material | Suits | Notes |
|---|---|---|
| Abrasion resistant steel plate | General impact and sliding, cut and fitted on site | Grades of around 400 to 500 Brinell, harder plate wears longer but is more brittle |
| Chromium carbide overlay | Severe sliding abrasion on chute bottoms and spoons | Hard weld overlay on a mild steel backing, cracks under heavy impact |
| Ceramic | Very high sliding wear, fine and abrasive material | Alumina tiles on steel or in rubber, brittle under large lumps unless rubber backed |
| Rubber | Impact from small to medium lumps, wet fines, noise | Absorbs impact, cut by sharp heavy lumps at speed and degraded by heat and oil |
| Polyurethane | Wet sliding and impact, screens and launders | Tough and light, limited by temperature |
| UHMW polyethylene | Low friction where sticky material hangs up | Helps flow, wears fast under impact and heavy abrasion |
| Rock box (material on material) | Heavy impact where the stream falls far | The stream lands on trapped ore, but can hold up wet or sticky material |
Laying out liners
Liners are laid like roof tiles. Each joint steps down in the direction of flow, so material passes over the edge instead of striking it. Fastener heads sit below the wear face or behind a wear cap, so the bolt does not wear away before the liner. Liner sizes are set by the weight a crew can handle in the space, with lifting points where they are needed. A shift in the stream after a change of belt speed or throughput moves the wear zones, so the layout should be checked against the stream, by observation, wear readings or a DEM model.
Lay liners so the flow steps down over every joint. An edge that faces the flow wears through first and channels the stream into the shell.
Liner problems
The costliest liner failures are not worn liners. They are liners that wear through unnoticed, liners that fall onto the belt and rip it, and changes that overrun the shutdown. Each traces back to the same gaps: no measurement, no attention to fasteners, and no planning for the change.
| Problem | Cause | Result |
|---|---|---|
| Holes through to the chute shell | Liners run past their wear limit without measurement | Spillage, chute plate damage, an unplanned stop |
| Liners falling onto the belt | Bolt heads worn away, the wrong fasteners, missing backing | A ripped belt, the most expensive liner failure |
| Joints wearing first | Liner edges set facing the flow instead of stepping down with it | Gaps that open and channel the stream into the shell |
| Blockage and hang up | A high friction liner, or a shape that lets fines stick | Chute blocked signals, cleaning in an awkward space |
| Short life at one spot | The stream landing where the design did not expect it | One liner changed far more often than the rest |
| Long changes | No liner drawing, liners too heavy to handle, no lifting points | Change outs that run over the shutdown |
A measured liner wear program
Liners are a natural fit for condition based maintenance. Remaining thickness is measured, trended and projected to the change limit, and the change is triggered by the trend instead of the calendar. Each liner position becomes a record in the CMMS with its material and supplier, and liner sets for the worst positions are held as critical spares. The shutdown plan then changes the liners that need it and leaves the rest.
| Task | What it involves | When |
|---|---|---|
| Liner drawing | Each liner numbered on the chute drawing with material, thickness, weight and fasteners | Once, then kept as built |
| Thickness readings | Remaining thickness at marked points, by ultrasonic gauge or by measurement through a hole | At set intervals, more often in the high wear zones |
| Wear trend | Readings against tonnes or time, projected to the change limit | After every reading, so the change is planned into a shutdown |
| Inspection | Holes, cracks, loose or missing bolts, build up | On the conveyor route through the inspection doors |
| Change out | Planned liner sets, lifting gear and the job plan ready before the stop | In shutdowns, grouped by chute |
| Review | Liner life by position and material, worst positions first | Each year, or when a liner fails early |
Common mistakes
- Changing all liners on a calendar instead of by measured wear.
- One material throughout the chute, regardless of the wear at each position.
- Liner joints facing into the flow.
- Countersunk bolts worn away so liners drop onto the belt.
- No liner drawing, so nobody knows what is fitted where.
- Liners too heavy to handle in the space, with no lifting points.
- Not recording liner life by position, so the worst positions never improve.
Common questions
What are chute liners?
Chute liners are replaceable wear surfaces bolted or welded inside transfer chutes, bins and hoppers so that the material wears the liner instead of the chute structure. They are made from abrasion resistant steel, chromium carbide overlay plate, ceramic, rubber, polyurethane or low friction plastics, chosen for the kind of wear at each position and how the material flows on them.
What is the best material for chute liners?
It depends on the wear at each position. Abrasion resistant steel plate is the general purpose choice. Chromium carbide overlay and ceramics last longest under sliding abrasion but can crack under heavy impact. Rubber handles impact from small and medium lumps and wet fines. Low friction plastics such as UHMW polyethylene help sticky material flow but wear quickly under impact. Most chutes use several materials.
What is a rock box in a chute?
A rock box is a ledge or pocket that traps a bed of the material being handled, so the falling stream lands on ore instead of steel. It handles heavy impact well and needs little lining, but it gives less control of the stream and can hold up and block with wet or sticky material.
How do you know when to change chute liners?
By measuring them. Each liner is given a number and a change limit, its remaining thickness is measured at marked points at set intervals, and the readings are trended against tonnes or time. The trend projects when each liner reaches its limit, so the change can be planned into a shutdown with the parts and lifting gear ready.
Why do chute liners wear unevenly?
Because the stream lands and slides in particular places. The impact zone where the stream from the head pulley first lands, and the sliding path below it, wear far faster than the rest of the chute. Changes in belt speed, material or throughput move those zones, which is why a liner that suddenly wears faster often means the stream has moved.
Key terms
Plain-language definitions from our glossary for the concepts this article leans on.
Standards and further reading
- Belt Conveyors for Bulk Materials, 7th edition (Conveyor Equipment Manufacturers Association (CEMA))
- AS/NZS 4024.3610:2015 Safety of machinery, conveyors, general requirements (Standards Australia)
- ISO 14224:2016 Collection and exchange of reliability and maintenance data for equipment (ISO)
Related case studies and tools
- Transfer chute redesign guided by DEM modelling (case study)
Related reading
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