How to Cast Polyurethane Scraper Blades: Machine and Process

July 17, 2026

Cast polyurethane belt scrapers (blades) clean the return side of conveyor belts in mining, ports, cement and bulk handling. Cast PU is used because it holds a working edge far longer than rubber, resists abrasion and oil, and can be tuned from tough to resilient by hardness. Blades are cast on a PU elastomer casting machine — we build the machine; you supply the PU system.

What Are Cast Polyurethane Scraper Blades

Cast polyurethane scraper blades are made by pouring liquid PU into a mould and letting it cure in place, unlike extruded or compression-moulded blades that are cut from stock sheet. Casting produces a blade with no seam and no internal stress from cutting, so the wear face stays even as the edge wears down.

PU is used instead of rubber or UHMWPE because it holds an abrasion-resistant edge longer, resists oil and most process chemicals, and can be tuned across a wide hardness range — Shore A 85–95 for scraper work, with higher hardness giving more wear life and lower hardness giving more flex for sticky or uneven belts. See MDI vs TDI for how the PU system choice affects that trade-off.

Below is what you need and the full process to cast polyurethane scraper blades in-house.

What You Need

PU elastomer casting machine (TDI or MDI system capable)
Blade moulds — per blade profile and size
Steel inserts/backing where the design bonds PU to a carrier
PU system + primer — sourced by you

The Process

Insert prep — degrease, blast and prime the steel carrier for a reliable PU-to-steel bond.
Conditioning — preheat mould; hold components at set temperature.
Meter, mix, pour — fixed-ratio dosing; fill to avoid voids at the working edge.
Gel, demould, post-cure.
Trim and inspect the edge — the edge is where the blade earns its life.

Key Parameters

Hardness — scraper blades are commonly Shore A 85–95; harder for abrasive ore, more resilient for sticky material
Ratio accuracy — soft spots at the edge cause early failure
PU-to-steel bond — primer and blast profile decide whether the blade delaminates
Post-cure — needed for full abrasion and tear resistance

Which Machine

We supply the TDI system casting machine for CPU scrapers. See the full PU elastomer casting machine range.

FAQ

What hardness for a belt scraper blade?

Usually Shore A 85–95. Harder blades last longer on abrasive ore; slightly softer, more resilient blades handle sticky or wet material better.

Why TDI systems for scrapers?

TDI-based cast elastomers are widely used for high abrasion and tear resistance, which is what a scraper edge needs. MDI systems are also possible; we advise per your target.

Do you supply the PU material?

No — we build the casting machine. You run your own or sourced PU system.

Tell us your blade profile, hardness and output — we will propose the right casting machine and quote.

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