Return Side Belt Cleaning: Components, Positioning and Failure Diagnosis

Return side belt cleaning is decided in the first 300 mm, not at the blade. Put the primary cleaner within 25 mm of the pulley face, put the secondary cleaner on the return run roughly one belt width downstream of it, and set blade tip pressure in the region of 20 to 40 N per 100 mm of belt width for a polyurethane tip. Those three numbers settle most of the outcome before any component is chosen. Here is the counter-rule we hand to maintenance crews: if a cleaner smears instead of lifting, the blade angle is wrong long before the material is wrong, and pressing harder only polishes the belt cover. What follows is a component table, a position table and a failure diagnosis chart you can carry out to the machine.

We have spent more than thirty years around bulk conveyors, most of it on sites where the return strand never stays clean through a full shift. Our works in Ningbo, China, builds belting, rollers, cleaning hardware and vulcanizing under one roof, so we tend to argue about a cleaning station as a system rather than as a part number. As a conveyor belt manufacturer we press the belt itself, and because we also supply the rollers and the scrapers that sit under it, we have to live with what the belt looks like six months later. That double view shapes everything below.

One boundary before the tables start. This page is about the hardware that lives under the discharge pulley and along the return strand: primary and secondary cleaners, brush rolls, air knives, ploughs, where they mount, how hard they press, how they wear and how they fail. It is not a general survey of cleaning methods. If you are still deciding whether mechanical cleaning suits your material at all, read our conveyor belt cleaning methods page once; we send you there and then stay with the components. Wash and spray systems belong to a separate subject and we do not open it here.

01Where Carryback Actually Lands on the Return Run

Carryback does not fall in one place. It leaves the belt as a thin film at the discharge pulley, then keeps shedding at different points along the return strand as the belt flexes over each conveyor roller. By the time the strand reaches the tail pulley, most of what was stuck to the cover has either dropped into the structure below or been pressed onto a roller shell. Knowing where the loss happens tells you which component belongs where. It also usually shows why a single scraper at the head pulley cannot cover the whole strand.

The pattern is fairly repeatable across materials. Wet fines shed early; dry powder re-wets in humid air and holds on longer; clay and damp ore press into the cover and shed only after they dry and crack. On one 1,200 mm limestone belt running at 2.8 m/s we walked the return strand with a scraper and a weigh tin. Roughly 70 percent of the recovered carryback came off inside the first metre past the discharge, and the rest was still arriving at the tail drum two hundred metres later. That is why we treat the primary and the secondary cleaner as a pair rather than as alternatives.

Belt condition from the loading zone feeds straight into this. Deep impact scars in the cover collect fines that a blade can never reach, and the cleaner then reads as "not working" when the cover is the real story. That is when it pays to look at the impact roller supplier question at the same time as the scraper, because a softer landing zone is a cheaper fix than a second cleaning stage.

Location	Typical Material Volume	Consequence	Cleaning Component
Discharge pulley face	Film 0.5 to 3 mm thick	Fines pack on lagging, belt wanders	Primary cleaner
Return run, 300 to 800 mm down	Shedding under the chute	Spillage on walkways, extra labour	Secondary cleaner
Mid-return strands	Thin dust film, re-wets	Roller shell build-up, edge wear	Brush roll or air knife
Tail pulley approach	Fine paste pressed by idlers	Tail drum lagging wear, wander	V-plough plus brush
Structure and stringers	Tonnes per month on coal lines	Roller seizure, fire risk	Plough plus drop chute
Loading zone return	Fines trapped in impact scars	Uneven blade contact, chatter	Impact idler, cover grade review

Reading the map against your own line

Walk the strand once with a torch and a notebook. Note the first point where material starts landing on the stringers, not where the pile has grown largest. That first point is where your effective cleaning ends, and it is nearly always closer to the head pulley than the crew expects. The second number to note is where the belt is still visibly dirty as it turns under the tail drum. Those two marks, taken together, define the working length you have to cover with hardware.

If the whole strand is dirty but the head area is clean, the problem is usually not pressure but fit: the blade is bridging over a low spot, or it is worn to a flat face that rides on the peaks. If material arrives at the tail pulley in ribbons rather than dust, the carryback is sticky and mechanical scraping alone will fight a losing battle; that case is treated in Section 11. For orientation, the table below puts the five common components side by side, so you can see which jobs overlap before we take them one at a time.

Component	Function	Position	Maintenance Need	Best Use
Primary cleaner	Takes the bulk film	At the discharge pulley	Blade check every 500 h	All bulk lines, wet or dry
Secondary cleaner	Finishes the thin film	One belt width downstream	Angle and spring check	Sticky fines, dusty loads
Brush roll	Sweeps loose dust	Mid-return, after a blade	Bristle length check	Dry powder, light belts
Air knife	Blows dust clear	Anywhere on the return	Slot and air supply	Dry granules, food and packaging
Plough	Diverts to the sides	Near the tail pulley	Wear strip and clearance	Wet or sticky bulk, coal, ore

02Primary Cleaner: Blade Geometry and Mounting

The primary cleaner is the one that takes the real load, so its geometry matters more than its brand. A blade that meets the belt at the wrong angle either rides up on the film or digs in and shaves the cover. In our experience on aggregate and clinker lines, a polyurethane blade held at a working tip angle of about 15 to 20 degrees from the belt surface lifts material cleanly, while anything under 10 degrees tends to smear the film sideways instead of releasing it. Metal tips tolerate a shallower angle, but they also cut faster when the belt surface is uneven.

Mounting distance is where most installations go wrong, and it is not a matter of taste. The blade has to be downstream of the point where the belt leaves the pulley, and close enough that the belt has not yet started to sag away from the pulley's curve. Twenty to 25 mm from the pulley face is our normal starting point; beyond 40 mm the belt has lost its support and the blade is chasing a moving target. We have reopened stations set at 90 mm where the scraper had been adjusted to near maximum spring pressure and still could not keep up with a shedding belt.

Blade forms and what each one is for

The three forms below cover almost everything we fit. The choice is driven by belt speed and material, and the wrong form shows up quickly as chatter or as an unremoved ribbon down the centre of the belt. As a conveyor belt supplier we see all three on the same site, often on lines that look identical from the walkway.

Blade Form	Contact Pattern	Angle Range	Mounting Distance	Best Use
Single straight edge	Line contact, full width	15 to 20 degrees	20 to 25 mm	General bulk, speeds under 3 m/s
Segmented edge	Line contact, independent tips	15 to 22 degrees	20 to 30 mm	Wide belts, crowned or uneven cover
Tungsten carbide tip	Line contact, high stiffness	10 to 15 degrees	25 to 35 mm	Abrasive ore, mechanical joints
Solid polyurethane	Line contact, compliant	15 to 20 degrees	20 to 25 mm	Sticky fines, warm belts, fast lines

03Secondary Cleaner: Position, Angle and Pressure

The secondary cleaner is a finishing tool, and it only earns its place if the primary has done its share. Its job is the thin film that survives the first scrape: the microlayer pressed into the cover, the damp dust that re-adheres as the belt travels. Because that film is thin, the secondary blade works with much less pressure than the primary and at a steeper angle. Our usual setting is a tip angle of 10 to 15 degrees against the belt and a pressure band of 15 to 25 N per 100 mm of width. Push a secondary cleaner to primary pressures and you buy nothing but heat and blade wear.

Position is the second lever. The secondary sits on the free return run, and one belt width downstream of the primary is the starting figure we quote. On a 1,400 mm belt that is about 1.4 m. Closer than half a belt width and the two blades fight each other across the same ripple in the belt; further out than two belt widths and the belt has started to sag between idlers, so the blade contacts the crown of the sag and misses the troughs either side. Springs or torsion mounts matter here more than at the primary, because the secondary has to follow that sag as it changes with load and temperature.

Settings that work on real lines

The table below is the band we start from on a typical aggregate or clinker belt, and the notes column is where the arguments usually happen. A secondary cleaner on a high-speed belt needs the higher end of the angle range and the lower end of the pressure range. On a slow, wet line the opposite tends to hold. As a supplier of the industrial conveyor belt that runs under these blades, we would rather see a conservative setting that holds for a year than an aggressive one that lasts a season.

Component	Distance from Pulley	Blade Angle	Pressure	Notes
Primary, polyurethane	20 to 25 mm	15 to 20 degrees	20 to 40 N/100 mm	Spring pre-load set cold, checked hot
Secondary, polyurethane	1 belt width	10 to 15 degrees	15 to 25 N/100 mm	Must follow return-run sag
Secondary, carbide	0.8 to 1.2 belt widths	8 to 12 degrees	25 to 35 N/100 mm	Not for mechanical fastener joints
Brush roll	1.5 to 2 belt widths	Tangent contact	Bristle deflection 5 to 10 mm	Counter-rotate at 1.5 to 2x belt speed

04Brush Rolls: When They Beat a Blade

A blade is a line contact, and line contacts are helpless against dust that has settled into the weave of the cover rather than sitting on top of it. That is the niche a brush roll fills. A brush sweeps a band of contact a few millimetres wide, and if it counter-rotates against belt travel it lifts loose material out of the surface texture instead of pushing it along. On a dry, dusty line, a well-set brush will recover material a polyurethane blade simply cannot reach.

The trade is speed and maintenance. A brush that turns too fast throws dust into the air where it settles on the structure, and a brush that turns too slowly leaves streaks. We normally run the counter-rotation at 1.5 to 2 times belt speed, with bristle deflection of 5 to 10 mm. Nylon holds up well in dry, ambient conditions. Polypropylene is cheaper but softens above about 90 °C, so it has no place on a clinker belt. Steel wire is for hot, coarse duty, and it will mark a soft cover, which is why we rarely fit it on anything under a 6 mm cover.

Matching the filament to the material

The table below maps filament choice to the material and the belt, because the wrong filament is the most common reason a brush is blamed for poor cleaning. Where the load is both abrasive and fine, as on a quarry screen deck, we sometimes pair a brush with a heavier rubber conveyor belt cover rather than raise the brush pressure, since the cover is cheaper to specify correctly than the brush is to replace quarterly.

Filament Material	Speed	Application	Limitations
Nylon, 0.5 to 0.8 mm	1.5 to 2x belt speed	Dry powder, grain dust, cement	Softens on hot clinker duty
Polypropylene	1.5 to 2x belt speed	Light, cool packaging lines	Temperature ceiling near 90 °C
Steel wire	1.2 to 1.5x belt speed	Hot sinter, coarse ore, heavy scale	Marks thin or soft covers
Abrasive nylon	1.5 to 2x belt speed	Moist fines, sticky ash	Wears the roll faster than plain nylon

05Air Knives and Air Blades

An air knife has no wearing part that touches the belt, which is the whole argument for it. A narrow slot directs a sheet of compressed air across the strand, and the shear of that sheet lifts dry dust off the cover and carries it into a hood. Nothing scratches the belt, nothing chatters, and there is no blade to adjust. On food, packaging and fine-chemical lines where a metal or polymer edge is unwelcome, that is often decisive.

The catch is that air knives need dry material and a real air supply. Wet or sticky carryback will not move for any reasonable pressure, and pushing the pressure higher just wastes energy and atomises whatever moisture is present. We size most installations at 2 to 6 bar with a slot of 0.5 to 2 mm, which gives an effective cleaning band of 30 to 60 mm across the strand depending on standoff. The air has to be captured downstream, or you have moved the dust from the belt to the walkway, and the cover must be rated for the environment; a light transmission belt manufacturer product family shares the same plant but not the same cleaning logic, and we keep the two conversations separate.

Air settings and where they stop working

Parameter	Typical Setting	Coverage Width	Where It Stops Working
Slot pressure	2 to 6 bar	Slot plus standoff	Above 6 bar noise and energy rise sharply
Slot width	0.5 to 2 mm	30 to 60 mm	Below 0.5 mm the slot clogs with dust
Standoff to belt	30 to 50 mm	Widens with standoff	Beyond 60 mm the jet loses its edge
Material moisture	Dry to the touch	Full width	Wet or tacky loads defeat it entirely

06Ploughs and V-Ploughs on the Return Run

A plough does not scrape; it steers. Set just above the belt with a small clearance, its angled wings push material that is already lying on the strand out to the edges, where it falls into a chute or collection box. The plough is the oldest and bluntest tool in the kit, and on wet or sticky bulk it is often the only one that keeps working after a blade has given up. It tolerates the ragged surface and the soft cover that make a scraper chatter.

Geometry is simple and unforgiving. A single diagonal plough runs at about 30 to 45 degrees to the belt centreline and needs its own discharge path at the leading edge, or it simply re-deposits material further along. A V-plough puts two wings on the same frame and throws material to both sides, which suits belts under about 1,200 mm where a single chute would be cramped. Clearance is the number to protect: 3 to 5 mm above the cover is normal, and if the head of a splice lifts the belt, that clearance has to grow or the plough will catch it. For a plant buying wholesale conveyor belts in volume, the plough is usually the cheapest way to keep the return strand under control at the tail end.

Plough layouts and their limits

Type	Angle	Position	Function	Limit
Single diagonal	30 to 45 degrees	1 to 2 m before tail pulley	Diverts to one side	Needs a clear side discharge
V-plough	35 to 50 degrees per wing	Before tail pulley	Diverts to both sides	Crowded on narrow frames
Wing plough	40 to 55 degrees	Mid-return	Guides material to one chute	Wears quickly on abrasive ore
Plough with wear strip	As above	Before tail pulley	Replaceable edge, less downtime	Strip must be reset after fitting

07Mounting Position Relative to the Pulley

Every cleaner in this article is only as good as the millimetres between it and the pulley. The reason is geometry, not tradition. The belt wraps the discharge pulley and then leaves on a tangent; for a short distance past that tangent it is still held in shape by its own stiffness. A blade placed inside that supported zone meets a belt that is straight and taut across its width. Move the blade half a metre further and the belt has begun to ripple between the first return idlers, so the blade now sees a wavy surface and can only clean the peaks. This is why we insist on position before pressure in every commissioning.

Two examples, both from lines we have measured. On a 1,000 mm wide stone belt at 2.0 m/s, the first return idler sat 620 mm past the pulley centre. A primary cleaner was fitted 90 mm from the face, which put it safely inside the supported zone; the crew had been told 90 mm was generous and safe. On a 1,200 mm coal belt the same figure gave 110 mm, still inside the zone but only just, and the engineers narrowed it to 25 mm to shorten the blade's lever arm. The lever arm is the point: a blade at 25 mm has almost no mechanical advantage against the belt, while the same blade at 300 mm on a sagging strand both under-cleans and chatters.

Two worked positions

Case one: 1,000 mm belt, 900 mm diameter head pulley, primary cleaner. The blade tip sits 22 mm from the pulley face, at a tip angle of 18 degrees, with a spring pre-load of 240 N across the width, which is 24 N per 100 mm. Case two: 1,400 mm belt, secondary cleaner on the return run. One belt width downstream is 1,400 mm from the primary, tip angle 12 degrees, pressure 20 N per 100 mm, mounted on a torsion arm so it can follow up to 15 mm of sag change between empty and loaded running. Both cases assume the strand is properly supported: if idler spacing is excessive, fix the idler set first, and our conveyor idler roller guide covers that number.

Component	Distance from Pulley	Blade Angle	Pressure	Notes
Primary, belt under 1,000 mm	20 to 25 mm	15 to 20 degrees	20 to 30 N/100 mm	Inside the supported tangent
Primary, belt over 1,000 mm	20 to 30 mm	15 to 20 degrees	25 to 40 N/100 mm	Segmented blade suits crowned cover
Secondary	1 belt width	10 to 15 degrees	15 to 25 N/100 mm	Follows sag, needs torsion mount
V-plough	1 to 2 m before tail	35 to 50 degrees	3 to 5 mm clearance	Clearance grows at splice locations

08Blade Pressure and Wear Limits

Pressure is the setting crews reach for first, and it is the one that does the most damage when chosen badly. A blade pressed too hard no longer cleans; the tip folds back, the contact patch widens, and the edge rides on a cushion of its own compliance. On a warm belt the friction also raises the cover temperature, and we have measured cover surfaces 12 to 18 °C above ambient directly behind an over-tensioned scraper. Under-cleaning and over-pressing look different in the field. Under-pressure leaves streaks and a shiny, moist film. Over-pressure leaves a polished, slightly glazed strip and a blade edge that has gone round.

Wear limits are easier to state than pressure, because they are measurable. A polyurethane tip that has lost about a third of its new section, or about 8 to 10 mm of its height, has reached the point where its compliance has changed and it should be renewed. Past that, the blade no longer returns to shape and the pressure setting you made last month is meaningless. Where the material is genuinely abrasive, a harder cover helps more than a harder blade, and the case for a heavier abrasion resistant conveyor belt guide should be weighed before the blade grade is changed. As a conveyor belt factory we would rather see the two decisions made together.

Wear limits by tip material

Tip Material	Shore A	New Thickness	Replacement Threshold	Check Interval
Polyurethane, soft	80 to 85	20 mm	Below 12 mm	Every 500 h
Polyurethane, standard	90	20 mm	Below 12 mm	Every 500 h
Polyurethane, hard	95	20 mm	Below 14 mm	Every 500 h
Tungsten carbide	Not applicable	12 mm insert	Insert worn flush with holder	Every 1,000 h
Rubber	60 to 70	25 mm	Below 15 mm	Every 350 h

09Tip Material and Shore Hardness

Hardness is the single number that decides how a tip behaves, and it cuts both ways. A soft tip conforms to an uneven cover, which is why it survives on a worn or crowned belt, but it also deforms under load and loses its edge sooner. A hard tip holds its shape and scrapes cleanly, yet on a belt with fasteners or deep scars it transfers shock straight into the mounting frame. The middle of the range absorbs most industrial duty, which is why 85 to 90 Shore A covers the majority of the blades we supply.

Heat is the hidden variable. Polyurethane softens as it warms, so a tip rated 90 Shore A at 20 °C may behave like 82 Shore A on a belt running at 70 °C. On hot duty the whole angle-and-pressure setting has to be taken cold and re-checked hot, ideally by measuring the cover temperature at the cleaning station rather than the air temperature of the gallery. The wear reference we ask buyers for is a volume loss figure; an abrasion test such as DIN 53516 gives a number in cubic millimetres, and a 90 mm³ compound will outlast a 150 mm³ one by roughly the ratio of the two figures. For context, our rubber conveyor belt cover grades page lists the same range for belt covers, and the logic transfers directly to cleaner tips. Separately, a V-belt manufacturer will quote hardness for a belt's undercord, which is a different question entirely; do not read one number across both.

Material and hardness selection

Material	Shore A	Wear Reference	Best Use
Soft polyurethane	80 to 85	Around 90 mm³, DIN 53516	Uneven covers, high-speed belts
Standard polyurethane	90	Around 150 mm³, DIN 53516	General bulk carrying
Hard polyurethane	95	Around 120 mm³, DIN 53516	Dry abrasive fines, steady belts
Tungsten carbide	Not applicable	Insert, wear by chipping	Heavy ore, high abrasion
Ceramic-tipped rubber	70 base	Low, but brittle	Severe abrasion, low shock

10Interaction With Belt Tracking and Training

A cleaner and a tracking problem are never independent. The blade sits on the belt, and the belt edge is what the training system is trying to steer. When a cleaner removes material evenly but the belt is mistracked, the blade wears unevenly and the wear pattern becomes the visible symptom of a tracking fault. When a cleaner is mounted square but the structure has been built out of line, the blade may actually push the belt sideways. We have seen a badly set plough take a belt from running true to rubbing the frame within one shift.

The interaction runs both directions, and the order of correction matters. Fix tracking first, then set the cleaner. A belt that wanders by 30 mm across a shift will produce a blade worn 30 mm off centre, and no pressure setting will rescue that. If the return strand drifts because the return idlers are not square, address the idlers; our EP conveyor belt tracking guide works through the alignment sequence, and where a permanent correction is needed a self aligning roller in the return run can hold the belt without fighting the cleaner.

Tracking symptoms caused by cleaning hardware

Effect on Tracking	Underlying Cause	Correction
Uneven blade wear, belt pulls one side	Cleaner frame not square to belt	Re-square the frame against the pulley
Edge fray, blade strips at one end	Belt already mistracked	Train the belt, then reset blade
Belt pushed sideways at the plough	Plough angle too steep for the speed	Reduce wing angle by 5 to 10 degrees
Wander appears only under load	Insufficient sag support on return	Add a return idler downstream

A clean belt tracks better than a dirty one, but tracking has to be corrected before the cleaning station is tuned.

11Interaction With Buildup and Sticky Material

Sticky material changes the rules, because the failure is no longer at the blade but around it. Clay, damp ore, biomass and fertiliser do not fall away when scraped; they roll up in front of the tip, form a ridge, and then either drop as a lump or wrap the first return roller. Once a roller shell has a growing jacket of material, its effective diameter rises and the belt path changes, which drags the story back into tracking. We treat buildup as a cleaning problem and a roller problem at the same time.

Two adjustments usually help before anything is replaced. First, move the secondary cleaner closer to the primary on sticky duty, because material that re-adheres in the first half metre is easier to remove than material that has set. Second, break the seal between belt and roller with a roller that is built for it: a sealed conveyor roller survives the fine dust that a standard bearing will not, and on sand and aggregate duty a sand washing conveyor belt with a smooth cover sheds the paste more readily than a heavily patterned one. Where the air itself is full of fines, a dust resistant conveyor belt reduces how much of that dust ends up in the bearings. As a conveyor belt distributor we also see profile belts in these duties, and we will say plainly that a chevron or cleated belt belongs in the scraper discussion only if you accept that a straight blade cannot clean between the profiles.

Sticky duty and what actually works

Sticky Condition	What Happens	Practical Countermeasure
Damp clay, 15 to 25 percent moisture	Rolls in front of the blade, drops in lumps	Secondary cleaner close to primary, soft tip 80 to 85 Shore A
Wet fines on a warm belt	Thin film re-adheres behind the blade	Brush roll between the two blades
Fertiliser and salt, hygroscopic	Crusts on the cover overnight	Plough near the tail plus end-of-shift run-empty
Buildup on return roller shells	Diameter grows, belt path shifts	Sealed roller, scraping access, inspection window
Biomass and food waste	Fibrous mat wraps the roller	Air knife where dry, plough where wet

12Discharge Chute and Cleaner Interface

The chute is not scenery. A cleaner that throws material into a dead pocket merely builds a shelf, and after a few weeks the shelf collapses back onto the belt. The blade has to discharge into a path with a downhill run and enough room for the material to clear the blade pocket at the belt's full speed. What we look for first is whether the chute lip sits ahead of the blade's throw direction, because if it does not, carryback falls into the gap between blade and chute and then rides the return strand as a fresh load.

Clearance is the second point. A blade cannot be serviced if the chute leaf is 150 mm from the frame, and a crew that cannot reach the tension bolts will simply leave the cleaner to wear out. We like at least a 400 mm maintenance gap and an inspection opening on the drive side. Where a plant substitutes a heavier rubber conveyor belts grade with a thicker cover, the blade geometry stays the same but the chute lip may need to move, because the thicker belt changes the discharge trajectory slightly at the pulley.

Chute faults that read as cleaner faults

Chute Issue	Position	Reported Risk
Lip ahead of blade throw	Directly under scraper	Material re-deposits on return strand
Dead pocket behind the lip	Side of chute	Shelf forms, later collapses onto belt
Under 400 mm service gap	Drive side of frame	Cleaner never re-tensioned after wear
Cracked wear liner above blade	Chute wall	Falling plate strikes blade and belt
No access door for inspection	Head end	Faults found only at shutdown

13Failure Diagnosis: Smearing, Chattering, Edge Damage

Three failures account for most of the emergency calls we take, and each one has a signature. Smearing means the blade is skating on the film rather than lifting it, and the cause is almost always angle before pressure. Chattering is a stiffness problem: the blade and its mount are being excited by the belt joint or by a ripple in the strand, and the fix is usually in the mounting arm, not the tip. Edge damage, where the blade frays across a short length near one edge, is a tracking or splice signature, and it will return after every blade change until the belt is trained.

The diagnosis habit that saves money is to check in a fixed order and to record what you find. Look at the tip first, because a round edge tells you pressure, and a chipped edge tells you impact. Then look at the belt surface immediately behind the blade, because a glazed strip means over-pressure and a shiny wet streak means under-pressure. Only then adjust anything. Change two settings at once and you learn nothing; the same fault usually returns a month later, masked rather than fixed.

Failure diagnosis chart

Symptom	Likely Cause	Check Order	Corrective Action
Film smeared sideways	Blade angle too shallow	Angle, then pressure	Raise tip angle by 5 degrees
Clean strip, shiny and glazed	Over-pressure, soft cover heating	Cover temperature, then pressure	Cut pressure by 30 percent
Rhythmic chatter at the joint	Tip too hard, mount too light	Joint, hardness, mount stiffness	Softer tip, stiffer arm, lower load
Edge chipping over a short length	Splice strike or local mistracking	Splice condition, belt tracking	Retain splice, train the belt
Blade wears to one side only	Frame not square, uneven load	Squareness, loading point	Re-square frame, check skirt
Carryback returns after a month	Wear threshold passed unnoticed	Tip height, spring load	Renew tip, reset tension cold

14Inspection and Replacement Intervals

A cleaning station that is inspected on a schedule is cheaper than one that is inspected after a spill. The schedule does not have to be elaborate, but it does have to be written down, because the two failures that cost the most are both slow: a tip that has passed its wear threshold and a spring that has lost pre-load. Neither announces itself. The belt simply gets dirtier over a period of weeks and the crew absorbs the extra cleanup as part of the shift.

We recommend a short walk-round weekly, a measurement-based check at each planned shutdown, and a full reset whenever the belt is replaced or re-spliced. Because a new belt changes the running tension, the blade contact will shift after a belt change even if nobody touched the cleaner, so the reset is not optional. The intervals below are a starting point for a two-shift operation; a three-shift plant on abrasive ore should halve them.

Inspection register

Item	Interval	Criterion
Tip height, primary	Every 500 h	Renew below 12 mm of 20 mm
Tip height, secondary	Every 500 h	Same threshold, check both ends
Spring pre-load	Every 1,000 h	Within 15 percent of set value
Blade contact across width	Weekly walk-round	Even mark, no gap over 100 mm
Roller buildup on return	Weekly walk-round	No jacket over 3 mm
Plough clearance	Monthly	3 to 5 mm above cover

15Retrofit Checklist for Existing Conveyors

Retrofitting a cleaning station onto a conveyor that was built without one is mostly a space problem disguised as a hardware problem. The belt width is known, the material is known, and the blade can be sized in an afternoon. What is not known is whether there is a mounting surface within 25 mm of the pulley, whether the chute has a spare opening, and whether anybody can reach the tension bolts with a spanner. Access is usually what kills a retrofit, not cleaning performance.

Work through the list before ordering, and measure on site rather than from a drawing. Drawings lie in exactly the places that matter here: the distance to the chute lip, the structural member that turns out to be a cable tray, the clearance under the frame. Two other parts of the line are usually worth reviewing at the same time, because a retrofit is the cheapest moment to fix them. The roller set is one, and our conveyor roller types and load ratings reference covers the width and spacing questions. The splice is the other, because a mechanical fastener will dictate whether you can use a carbide tip at all; the conditions are set out in our conveyor belt splicing ultimate guide.

Retrofit checklist

Check	What to Measure	Accept If
Mounting surface	Distance from pulley face	20 to 30 mm achievable
Access to tension bolts	Clear gap on drive side	At least 400 mm
Chute opening	Spare lip or flange	Discharge downstream of blade
Return idler spacing	Distance to first idler	Under 1,500 mm for belt under 1,200 mm
Splice type	Vulcanized or mechanical	Vulcanized for hard tips
Discharge pulley diameter	Face width and lagging type	Blade width covers face minus 50 mm
Structural stiffness	Section under the frame	No visible flex under load

16Measuring Cleaner Performance

If you cannot measure a cleaner, you cannot improve it, and the numbers are easy to take. The simplest test is a weighed clean-belt sample: run the belt empty for two minutes after the station, stop it, and scrape a 300 mm square of return belt immediately downstream of the cleaner into a bag. Weigh the bag. Compare it with the same sample taken 2 m further along the strand. The difference is what your cleaning station is leaving behind, and it turns a subjective argument into a figure the maintenance planner can act on. As a conveyor roller supplier we use the same approach when a client wants to justify a second cleaning stage or a better return idler set.

Three or four metrics are enough to run a station properly. Track recovered material per shift, blade wear per 100 hours, cover temperature at the station, and the unplanned cleanup hours on that section. All four are repeatable, which is the only property that matters in a log. The table below is the version we ask plants to keep.

Cleaner performance log

Metric	Measurement Method	Target	Frequency
Material recovered	Weighed 300 mm sample	Under 15 g per sample	Weekly
Blade wear rate	Tip height against last reading	Under 1 mm per 100 h	Every 500 h
Cover temperature	Infrared at blade exit	Under 15 °C above ambient	Monthly
Cleanup hours	Shift log for that section	Under 10 min per shift	Daily
Return roller buildup	Depth gauge on shell	Under 3 mm jacket	Weekly

Lead times and minimum order quantities for cleaning hardware follow normal industry ranges and depend on whether the frame is standard or built to your drawing; the exact figure is always confirmed against the site measurements and the belt data. Nothing on this page replaces that confirmation.

17Frequently Asked Questions

How far from the pulley should a primary cleaner sit?

20 to 25 mm from the pulley face is where we start. That keeps the blade inside the zone where the belt is still straight and taut after leaving the pulley, so the tip meets a plane rather than a wave. Past 40 mm the belt has begun to sag between return idlers and the blade starts missing the low spots.

What blade angle stops smearing?

Raise the tip angle. Smearing is a shallow-angle fault, not a pressure fault, so a blade held at 8 degrees will keep pushing the film instead of lifting it no matter how hard you press. Take it to 15 to 20 degrees and the same blade releases material cleanly.

When is a brush roll better than a blade?

When the material is dry and fine, and the problem is dust settled into the cover rather than a film sitting on top of it. A blade is a line contact and cannot reach into the surface texture. On a dusty line a counter-rotating brush recovers material that a polyurethane tip leaves behind.

How much tip pressure is too much?

If the cover behind the blade is polished and glazed, or reads more than about 15 °C above ambient, you are past the useful range. For a polyurethane tip we work between 20 and 40 N per 100 mm of belt width, with the higher figures reserved for the primary on wide, heavy belts.

How often should cleaner blades be replaced?

By height, not by calendar. A 20 mm polyurethane tip is due when it drops below about 12 mm, which on a two-shift aggregate line usually arrives somewhere between 4 and 9 months. Check it every 500 running hours and the question answers itself.

Does a return cleaner affect belt tracking?

Yes, in both directions. A mistracked belt makes a cleaner wear unevenly, and a badly set plough or an out-of-square frame can push a belt sideways. Correct the tracking first, then tune the cleaner, because the reverse order tends to hide the cause.

What is the right position for a secondary cleaner?

Roughly one belt width downstream of the primary, on the free return run. Closer than half a belt width and the two blades fight across the same belt ripple; further than two belt widths and the belt has already sagged, so the blade rides the crown and misses the troughs.

Why does a cleaner chatter on a fast belt?

Usually because the tip is too hard and the mounting arm is too light for the speed. The joint passing under the blade excites the assembly, the blade hops, and then the edge chips. A softer tip, a stiffer arm and a lower spring load cure most cases.

Can a plough replace a scraper?

No. A plough steers material that is already lying loose on the strand out to the sides; it does not lift a film off the cover. It is the right tool for wet and sticky bulk near the tail pulley, and it is a poor substitute for a primary cleaner at the discharge pulley.

What causes edge damage at the cleaning station?

A splice strike or a local mistracking fault, nearly every time. If the damage is over a short length near one edge, look at the joint first and the belt path second. Changing the blade without fixing either will simply reset the same failure.

How do I retrofit cleaners onto an existing conveyor?

Measure the site, not the drawing. You need a mounting surface 20 to 30 mm from the pulley face, a chute opening downstream of the blade, and at least 400 mm of clear space to reach the tension bolts. Access is what kills most retrofits, not cleaning performance.

How do I measure whether a cleaner is working?

Weigh a 300 mm sample of return belt just downstream of the station and compare it with one taken 2 m further along. The difference is your carryback. Under about 15 g per sample on a 1,000 mm belt is a sensible target, and the figure is repeatable enough to justify further spending.

18Related Products You May Need

• Conveyor rollers and idlers for the return strand that carries the cleaning station.
• Rubber conveyor belts with cover grades matched to abrasive and sticky duty.
• Chevron and profile belts where incline handling sits alongside carryback control.
• The full product range for a single consolidated enquiry.

19Related Blog Posts

• Conveyor belt cleaner fundamentals for the wider selection view of blade hardware.
• Cleaning methods and schedules for the five cases where a scraper will not work.
• EP conveyor belt tracking before you blame the cleaning station for a wandering belt.
• Conveyor roller types and load ratings for the return idler set under the cleaner.