A metal or rubber part that must be replaced every quarter consumes the budget not through the part price itself but through production downtime at every replacement. Cast polyurethane breaks this cycle: using the free-casting process, a part of the required hardness is cast that lasts several times longer than rubber and is 6-7 times lighter than steel. TIMOL factory produces cast polyurethane parts for 12 industrial sectors. This article covers the material’s properties, the hardness scale, the economics of replacing rubber and metal, and the process for ordering parts to size.
What Cast Polyurethane Delivers in an Industrial Node
Cast polyurethane is a versatile structural elastomer that combines wear resistance, resilience, and chemical stability in one material. Abrasion per DIN 53516 is 38-39 mm³, meaning wear resistance approximately 2-5 times higher than standard rubber. This is the primary reason why polyurethane parts withstand abrasive conditions where rubber lasts only weeks.
The second strength is elasticity with shape recovery. Under compression and impact, polyurethane deforms and then recovers its geometry thanks to a rebound elasticity of 34-61 %. It absorbs impacts and noise but does not acquire the permanent set that rubber develops under sustained load. This makes it well suited for shock absorbers, seals, and dampers.
The third advantage is resistance to environment and temperature. Cast polyurethane operates in the range from -60 to +100 °C and withstands petroleum products, oils, dilute acids and alkalis, and salt solutions. It does not corrode, unlike steel, and does not age from ozone as rapidly as natural rubber. As a result, a single part can meet several requirements simultaneously — where steel is needed for wear resistance but fails on corrosion, and rubber is suitable for elasticity but cannot tolerate oil, polyurethane often proves to be the only material satisfying all conditions at once. A broader description of properties is available in the reference information section.
Free-Casting Technology and the Hardness Scale
Free casting is the pouring of a two-component polyurethane mix into a mould without high pressure. The mix of polymer base and isocyanate hardener has good flow, so it fills the mould under its own weight and accurately reproduces the geometry. Tooling for this casting method is less expensive than vulcanisation press moulds for rubber, making even single-unit production economically viable.
The hardness of the finished part is set by the formulation at the casting stage, in the range from 50 Shore A to 70 Shore D. Soft grades in the A range are used for dampers, seals, and elastic moulds. Hard grades, closer to the D scale, are used for loaded sliding bearings, rollers, and heavily loaded wheels. Lining and parts working in abrasive are made in the upper Shore A range, 80-95 Shore A, where resilience holds wear. Within this range, wear resistance and chemical resistance are also managed for the specific task.
Controlled formulation means that the same part can be made softer or harder to match the actual conditions of the node. A pigment added to the transparent base is used only for batch marking; it has no effect on service life or properties. A list of standard products is provided in the product catalogue.
Another practical advantage of free casting is the ability to cast polyurethane onto metal reinforcement. A wheel with a metal hub, a roller on a steel shaft, or a shaft with a metal core receives a wear-resistant working surface and a strong core in a single part. The metal is first cleaned, degreased, and coated with an adhesion primer; polyurethane is then cast so that after polymerisation the layer holds to the substrate for the full service life. This approach combines metal stiffness with the resilience and wear resistance of polyurethane without bolted or welded joints.
Comparison of Cast Polyurethane with Steel, Rubber, and UHMW-PE
Cast polyurethane occupies the niche between rubber and metal: it is more wear-resistant and stronger than rubber, lighter and quieter than steel, and outperforms UHMW-PE in elasticity. The table compiles reference data for materials from which wear parts are actually manufactured.
| 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 |
| NBR rubber | 80-150 | -30…+100 | 1.0-1.3 | 10-25 | 20-45 |
| SBR rubber | 100-200 | -40…+80 | 0.94-1.1 | 8-20 | 30-55 |
| 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 |
Polyurethane delivers the best balance: among elastomers it has the lowest abrasion while retaining resilience. UHMW-PE wears even less (15-30 mm³), but its rebound elasticity is only 5-10 %, so under impact it deforms without absorbing the energy. Steel wins on tensile strength but is several times heavier and corrodes. Rubber yields on wear and loses shape more quickly.
Economics of Replacing Rubber and Metal with Polyurethane
The primary economic benefit of switching to cast polyurethane is a lower replacement frequency. Because polyurethane wears several times more slowly than rubber, the part serves a longer cycle and there are fewer line shutdowns for replacement. For a production facility where a part wears out every quarter, this is a direct gain in operating continuity.
Engineer’s tip: calculate not the price of a single part but the cost of the node for a year, including downtime. A cheaper rubber part replaced four times a season totals more than a polyurethane part that runs the full season. And remember lining: there is often no need to cast a solid massive part — it is sufficient to apply a polyurethane layer to a metal substrate, preserving a strong core and adding a wear-resistant working surface.
The second saving factor is the elimination of expensive tooling. Free casting requires no high-pressure press moulds, so producing small batches and single parts to drawing is economically justified, and the cost of the mould is not spread over thousands of units as it is in rubber production. This is especially noticeable when repairing rare or outdated equipment where only a few non-standard-size parts are needed. A list of factory services is provided on the services page.
How to Order Cast Polyurethane Parts at TIMOL Factory
To place an order, submit a drawing or worn sample with dimensions and fits, and describe the operating conditions: load type, working medium, temperature regime, and desired hardness. Based on this data, the technologist will select the cast polyurethane formulation, calculate the geometry, and determine machining allowances.
Production is possible from a single part to production runs, including large parts and lining on metal substrates. The free-casting process makes even a single-unit order to a specific drawing economically viable. If you do not have a drawing, it is sufficient to submit a worn sample: the technologist will take dimensions from it, account for working clearances, and reproduce the part with a correction for the prior wear. This approach is convenient when the original documentation for the node is lost and production must be resumed quickly. To get a calculation and arrange production, contact TIMOL factory. Engineers will help select the material and organise production for your node.