A conveyor belt scraper works at the dirtiest point on the line: it removes adhering product, sand, ore, and moisture directly from the moving belt. Metal and rubber scrapers in these conditions rust, warp, and wear through in weeks — and the belt itself suffers with them. A polyurethane scraper from TIMOL factory gives service life several times longer than rubber, does not scratch the belt, and converts conveyor cleaning from emergency work into planned maintenance. This article covers why polyurethane wins in numbers, how a scraper is installed in a node, and how to order one for your drum.
Why a Polyurethane Scraper Outlasts Metal and Rubber
The primary reason is a simple fact: polyurethane abrades significantly more slowly than rubber and does not corrode like metal. Abrasion per DIN 53516 of cast polyurethane is 38-39 mm³, while for common SBR rubber it reaches 100-200 mm³ and for NBR remains at 80-150 mm³. Under the same cleaning conditions the polyurethane edge loses several times less material, so the replacement cycle is proportionally longer.
Metal as a scraper has different problems. A steel edge does not damp vibration, transmits impacts to the structure, and scratches the rubber belt, reducing its service life. Carbon steel also corrodes in a wet and aggressive environment, and its density of 7.7-7.9 g/cm³ versus 1.05-1.25 g/cm³ for polyurethane means a six-to-seven times heavier part on the same node.
Polyurethane combines a hard working edge with elasticity. Rebound elasticity of 34-61 % allows the scraper to closely follow the drum profile under light contact pressure, maintaining contact when the belt beats. It removes build-up cleanly but does not cut the belt. The operating temperature range from -60 to +100 °C covers cold shops and heated lines.
Where a Polyurethane Scraper Is Fitted and How It Is Installed
The scraper is installed in the discharge zone, most commonly at the drive drum where the belt changes direction and product separates from the belt surface. The edge is pressed against the belt by a spring or lever mechanism with adjustable contact force to compensate for wear and maintain consistent contact.
Constructively, a polyurethane scraper is manufactured as a solid plate, segmented cartridge, or edge element on a metal carrier. The segmented design is convenient in that a worn segment is replaced individually without removing the full cartridge. For reversible lines, a double-sided scraper with two working edges is made.
TIMOL’s free-casting process allows a scraper of any profile to be cast: straight edge, angled bevel, curved profile to a specific drum diameter. The working face geometry is set at the casting stage, so additional machining is not always required. The full list of profiles and associated conveyor products is in the polyurethane products catalogue.
Maintenance of a polyurethane scraper consists of periodically tightening the contact mechanism as the edge wears and checking the contact line. Unlike a metal scraper, a polyurethane one requires no build-up welding or geometry correction: when the working face is worn out, the part or segment is simply replaced with a new one. This reduces node maintenance time and removes the set of metal-dressing tools from the maintenance kit.
Comparison of Polyurethane with Rubber, Steel, and UHMW-PE
Polyurethane outperforms rubber and steel on the combination of wear resistance, weight, and belt friendliness, while UHMW polyethylene is inferior on elasticity. The table below summarises reference engineering properties of materials actually used in scrapers.
| Material | Abrasion DIN 53516, mm³ | Operating t, °C | Density, g/cm³ | Tensile strength, MPa | Rebound elasticity, % |
|---|---|---|---|---|---|
| Polyurethane TIMOL | 38-39 | -60…+100 | 1.05-1.25 | 39-87 | 34-61 |
| SBR rubber | 100-200 | -40…+80 | 0.94-1.1 | 8-20 | 30-55 |
| NBR rubber | 80-150 | -30…+100 | 1.0-1.3 | 10-25 | 20-45 |
| UHMW-PE | 15-30 | -200…+80 | 0.93-0.95 | 17-45 | 5-10 |
| Structural steel | n/a | -40…+500 | 7.7-7.9 | 370-700 | n/a |
UHMW-PE does have lower abrasion (15-30 mm³), but its rebound elasticity is only 5-10 %: under load it does not spring back to the drum profile as elastically as polyurethane. Rubber with higher abrasion loses the edge faster. Steel wins only on tensile strength but corrodes, is several times heavier, and damages the belt.
How to Choose Hardness and Scraper Profile
Hardness selection determines how cleanly the scraper removes product and how long the edge retains its geometry. For sticky and wet fractions that must be cleaned gently, medium hardness around 80-90 Shore A is used. For dry abrasive materials, harder polyurethane approaching the Shore D scale is chosen, where the edge geometry is retained longer.
Engineer’s tip: do not chase maximum hardness where the belt beats or has splices. An overly hard edge loses contact at surface irregularities and leaves build-up tracks. It is better to select hardness for the specific contact force and add spring compensation for wear. And remember: a level, well-set contact line matters more than hardness itself, because a misaligned scraper wears wedge-shaped and works on only part of its width.
Edge profile is selected for the drum diameter and contamination type. A straight edge is universal; an angled bevel deflects cleaned material to one side better; a curved profile conforms closely to a small drum. All these parameters are set by the factory technologist in the mould at the casting stage.
Industries and Typical Application Nodes
Polyurethane scrapers work in 12 industries where belt conveyors and transporters are present. In mining they remove ore, coal, and gangue from the belt at discharge, withstanding intensive abrasive. In metallurgy they clean charge and pellet feed belts.
Food and agricultural industries value polyurethane for chemical inertness: the scraper does not affect the product and cleans easily. It is installed on grain and compound-feed lines, and in poultry facilities on extended litter-removal mechanisms. The construction industry uses scrapers on sand, crushed stone, and concrete mix conveyors with fine and medium fractions. Further detail on material properties for different media is in the reference information section.
How to Order Scrapers to Size from TIMOL Factory
To place an order, send a drawing or sample of the worn part with dimensions; specify the drum diameter, belt width, transported material type, and operating conditions. Based on this data the technologist selects the hardness, edge profile, and polyurethane formulation, and calculates the geometry for your node.
Manufacturing is possible from one part to production batches for a line, including double-sided and segmented scrapers. Ready standard shapes are usually in stock. Ordering directly from the manufacturer eliminates intermediary markups and guarantees that the hardness and formulation match what is specified rather than a random market batch. For a calculation to your drawing and to place a manufacturing order, contact us via TIMOL factory contacts or review the work scope in the services section. Engineers will help select the material and organise production to your requirements.