A metal part that has to be replaced every quarter eats into the maintenance budget and shuts down the line at the worst possible moment. Polyurethane lining breaks this cycle: a wear-resistant elastomer layer takes the abrasion and impacts on itself, while the part itself works for years. Below I explain what polyurethane lining is, which assemblies are protected most often, why the material beats rubber, caprolon and steel by the numbers, and how to order manufacturing to your drawing.
What polyurethane lining is and what it delivers
Polyurethane lining is the application of a wear-resistant polyurethane layer onto the surfaces of parts subjected to intensive abrasion, impact and corrosion. The layer is reproduced by free casting, precisely follows the geometry of the part and provides a tight fit with no air pores.
The practical benefit comes from several effects. The wear resistance of TIMOL polyurethane exceeds rubber by 2-5 times, so the maintenance interval of the assembly is extended and downtime is reduced. The operating temperature range from -60 to +100 °C allows the coating to be used both in hot shops and in unheated warehouses. Polyurethane does not corrode, absorbs impacts and reduces noise, and the worn layer is easily recast while preserving the metal base of the part.
Which parts and assemblies are lined most often
Lining is used where the surface of a part is in constant contact with abrasive, slurry or bulk material. These are shafts and drums, elevator buckets, screens and screen decks, concrete-mixer scrapers, cyclones and hydrocyclones, hoppers, chutes and gravity feeders, as well as lining sheets to protect equipment walls.
Each of these assemblies fails in a similar scenario: abrasive wears down the working surface, water and reagents cause corrosion, and impact loads add cracks and scoring. Bare metal in such conditions has to be repaired or replaced regularly. A polyurethane coating takes the wear on itself and, thanks to its elasticity, absorbs impacts instead of transmitting them to the structure.
For example, concrete-mixer scrapers with a polyurethane coating keep their working edge far longer than metal ones, and elevator buckets get protection against abrasive wear from grain and ore. You can review the product range in the catalog of polyurethane products.
The economics of lining are most visible in repeated replacements. A bare metal part in an abrasive assembly has to be re-machined or replaced regularly, and each cycle is the cost of new metal plus line downtime during removal and installation. A lined part works longer between repairs, and when the coating reaches the end of its life, only the polyurethane layer is renewed, while the expensive metal base stays in service. That is why the total cost of ownership of the assembly over several years comes out lower than in a scenario with periodic replacement of solid-metal parts.
Polyurethane versus other materials: the numbers
In abrasion resistance polyurethane substantially outperforms rubber, and in the combination of wear resistance and elasticity it wins over caprolon and steel. Below are reference figures for the materials that really compete in lining.
| Material | DIN 53516 abrasion, mm³ | Working t, °C | Tensile strength, MPa | Hardness | Density, g/cm³ |
|---|---|---|---|---|---|
| TIMOL polyurethane | 38-39 | -60…+100 | 39-87 | 85A-95A | 1.05-1.25 |
| NBR rubber | 80-150 | -30…+100 | 10-25 | 40A-90A | 1.0-1.3 |
| Caprolon PA6/66 | 30-90 | -40…+100 | 60-85 | 75D-85D | 1.13-1.15 |
| Hardox 400/500 steel | none (metal) | -40…+250 | 1250-1600 | 370-540 HB | 7.8-7.85 |
The DIN 53516 abrasion of polyurethane is 38-39 mm³, whereas for NBR rubber it reaches 80-150 mm³, meaning rubber wears out 2-4 times faster under the same conditions. Caprolon has decent abrasion resistance (30-90 mm³) and high strength, but it is rigid, absorbs moisture and is brittle under impact, so it cracks where polyurethane simply springs back. Hardox steel gives maximum strength and hardness (370-540 HB), but it weighs 6-7 times more than polyurethane (density 7.8-7.85 versus 1.05-1.25 g/cm³), corrodes, does not flex and transmits impacts to the structure.
The advantage of polyurethane lies precisely in the balance: it combines low abrasion with elasticity and damping that neither rigid plastics nor metal have. That is why in assemblies with variable loads and impacts it lasts longer than harder but brittle materials.
How to choose hardness and the application technology
Hardness is selected to match the nature of the load, and the application method to match the geometry and conditions of the part. The general rule: the higher the pressure and the more precise the geometry required, the harder the polyurethane; the more impacts and vibration, the more elastic it should be.
TIMOL cast polyurethane is available in the range from 50 Shore A to 70 Shore D, so a single technology covers both soft damping elements and hard wear-resistant surfaces. For static loads where strength matters, a harder material is chosen; for dynamic loads where vibration absorption matters, a softer one.
In practice, hardness is tied to the specific task of the assembly. Scrapers, seals and damping elements that work in bending and impact are made in the Shore A zone, where the material is resilient and does not crack. Parts under high pressure are made harder, closer to Shore D, to hold the geometry under load. Screens and lining sheets that work in abrasive are made in the upper Shore A zone, 80-95 Shore A: the resilient material holds wear better than rigid Shore D. The application method also depends on the part: solid casting into a mould for finished products, lining of a metal base for shafts and drums, hot adhesion for monolithic protection of equipment walls.
Engineer’s tip: Do not automatically choose maximum hardness. In assemblies with impact loading, polyurethane that is too hard cracks, while a softer one takes the impact resiliently and lasts longer. The key to service life is surface preparation before casting: degreasing, shot blasting and an adhesive primer. It is exactly the quality of preparation that determines whether the lining will hold for its entire design life without delamination.
Repairability and maintenance of lining
The main economic advantage of polyurethane lining is its high repairability. When the layer reaches the end of its service life, it is removed and a new one is applied by free casting, while the metal base of the part stays in service. There is no need to manufacture a whole new part; only the worn coating is renewed.
Maintenance comes down to periodic visual inspection of the lining condition and timely replacement of elements that have undergone critical wear. Parts are often mounted on bolted, flanged or seated connections, which allows quick inspection without dismantling the whole assembly. Polyurethane does not crack under deformation and is resistant to hydraulic shocks, which minimizes the risk of emergency failure. The technical nuances of the material are collected in the reference information section.
How to order lining at the TIMOL plant
You can order polyurethane lining at the TIMOL plant from a ready drawing, from a technical description or from a dismantled part used as a sample. Production is carried out by free casting to the specific dimensions, loads and operating conditions of your assembly.
The process starts with a consultation where engineers select the hardness, application method and polyurethane grade for your task. The plant manufactures parts both to standard sizes and to individual drawings. To get a quote and recommendations for your assembly, get in touch with the TIMOL plant contacts. Experience with hundreds of assemblies will help select a solution that extends the service life of the part and cuts maintenance costs.