Rubber scrapers, seals and dampers on a conveyor often last only a few weeks, after which the line stops for replacement and the mechanic again cuts a gasket from sheet stock. Polyurethane on the same assemblies works for months, because it wears many times slower than rubber and holds a wider temperature range. Below we break down exactly where polyurethane beats rubber by specific figures rather than slogans, and how that translates into part service life.
How polyurethane beats rubber by the numbers
The main advantage of polyurethane is its resistance to abrasion: under the DIN 53516 test it loses 38-39 mm³, whereas SBR rubber wears by 100-200 mm³ and nitrile rubber NBR by 80-150 mm³. A smaller loss of volume means that with the same abrasive, a polyurethane part outlasts a rubber one roughly tenfold. It is precisely this difference that is relied upon when calculating the economics of switching materials.
The second significant advantage is temperature and oil resistance. TIMOL cast polyurethane works from -60 to +100 °C, while SBR is limited to a range from -40 to +80 °C, and NBR already begins to harden at -30 °C. At the same time, the oil resistance of polyurethane is rated as excellent versus weak for SBR and natural rubber. In other words, where rubber either goes cold-stiff or swells in oils, polyurethane stays in working condition.
Comparison table: polyurethane versus rubber
The table summarizes reference engineering data by standard methods. For abrasion, a lower value is better; for tensile strength and temperature range, a higher value means a wider margin.
| Parameter | Cast polyurethane (PU) | SBR rubber | NBR rubber |
|---|---|---|---|
| Abrasion, DIN 53516 | 38-39 mm³ | 100-200 mm³ | 80-150 mm³ |
| Working temperature | -60 to +100 °C | -40 to +80 °C | -30 to +100 °C |
| Tensile strength | 39-87 MPa | 8-20 MPa | 10-25 MPa |
| Hardness, Shore scale | 50 Shore A to 70 Shore D | 40-80 Shore A | 40-90 Shore A |
| Tear resistance | 40-120 kN/m | 8-35 kN/m | 10-50 kN/m |
| Oil resistance | excellent | weak | good |
The table is best read in pairs of parameters. For example, polyurethane has a tensile strength of 39-87 MPa versus 8-20 MPa for SBR, so it withstands three times more tensile force before failure. The tear resistance of polyurethane is 40-120 kN/m versus 8-35 kN/m for the same rubber, and that is exactly why polyurethane scrapers and blades do not chip along the edge where rubber ones tear.
Where the difference in abrasion delivers real savings
Polyurethane shows its biggest gain on assemblies that work under abrasion and impact. These are the lining of hoppers and chutes, elevator buckets, screens and screening-machine parts, rollers and wheels of transport carts, concrete-mixer scrapers. There a rubber part wears noticeably, and every few weeks the line is stopped for replacement, whereas a polyurethane part runs a much longer cycle.
The economics here are simple: if abrasion is 3-5 times lower, then the frequency of replacements falls by the same factor, and with it the total equipment downtime falls too. To select a material for a specific abrasive and load, it is convenient to start with the product catalog, which gathers typical items that the factory casts in series and to size.
Engineer’s tip: do not chase maximum hardness where there is impact. For purely abrasive friction, take 80-95 Shore A, but for impact loads it is better to keep the part a little softer, in the 80-90 Shore A zone, because too hard a part transmits the impact to the seat and cracks along the edge. Always clean the surface for lining down to bare metal and degrease it, otherwise the adhesion of the bonding layer will drop.
What to consider besides abrasion
Polyurethane loses to rubber in a few situations, and it is more honest to say so upfront. Under constant contact with steam and hot water above +100 °C, or with strong acids and alkalis, polyurethane hydrolyzes, and here a special rubber or fluoroplastic is sometimes more appropriate. Rubber is also cheaper per unit volume and faster to manufacture for simple flat gaskets in large batches.
However, on most industrial assemblies the decisive factors are service life and dimensional stability under load. Polyurethane does not flow, does not swell in oils and holds its fitting dimensions, so it is fitted on seals, supports and guides where precision matters. More detail on the properties and the open-casting technology is available on the page about the material.
How to switch from rubber to polyurethane
The switch begins not with the material but with the working conditions of the assembly: what the load is, what abrasive or chemistry is involved, the temperature, whether there is impact, and the fitting dimensions. From this data the technologist selects the hardness and formulation, after which the part is cast to your drawing or to a sample of the old rubber part.
Open casting makes it possible to reproduce the geometry precisely and build in the required hardness without an expensive mold, so the method is economical both for single parts and for series. The list of manufacturing and lining services is in the services section.
Practical conclusion
Polyurethane justifiably replaces rubber wherever a part works under abrasion, impact and contact with oils, and gives a service life roughly tenfold higher than standard rubber under the DIN 53516 test. To calculate a replacement for your assembly, send the drawing or a sample of the part to the TIMOL factory via contacts, and the engineers will select the hardness, calculate the tooling and the manufacturing lead time.