An ore bunker wall wears through in a single season. A rubber lining cracks in frost and degrades on oil contact. Hardox wear steel is expensive and heavy but transmits every impact of a falling lump to the structure, creating noise that exceeds permissible levels without ear protection. Polyurethane lining from TIMOL solves all three problems: it wears several times more slowly than rubber, absorbs impact rather than transmitting it, and does not corrode. This article covers lining methods, a material comparison in numbers, applications across industries, and how to order lining for your equipment.
What Polyurethane Lining Is and Why Equipment Needs It
Lining (from German Futter — lining) is the application of a protective layer to the working surface of equipment exposed to abrasion, impact, or corrosion. The protective layer takes the mechanical wear and is replaced when worn out, while the expensive metal substrate of the bunker, pipe, chute, or shaft continues in service.
Without lining, the metal substrate itself is the working surface. Steel bunker walls in a mining or processing plant wear through in one season of contact with ore, crushed stone, or coal; replacing the bunker is an expensive and lengthy shutdown. A polyurethane lining layer applied to the same bunker wall adds a wear-resistant surface that is maintained by periodic replacement of the lining, not the equipment.
The second function of lining is impact damping. Ore lump impact on steel creates a sharp noise impulse and a vibration that propagates through the structure to the foundations and adjacent equipment. A polyurethane layer with a rebound elasticity of 34-61 % absorbs the impact energy, reduces the noise level at the transfer node, and prevents vibration from reaching the structure. In production facilities adjacent to offices or laboratories, this noise reduction is not only a matter of comfort but a regulatory requirement. The full range of linings by application is in the product catalogue.
Lining Methods
TIMOL factory applies polyurethane lining by four methods, each selected for specific equipment geometry and operating conditions.
Polyurethane rings are the fastest method for conveyor shafts and rollers. Ready-made rings are stretched onto the shaft or roller body, secured by the elastic deformation of the material itself, and require no adhesive or special tooling. This method is used for routine roller maintenance: a worn ring is replaced in minutes directly at the conveyor. The ring thickness and hardness are selected for the material being conveyed and the shaft operating conditions.
Lining sheets are used for flat and curved large-area surfaces: bunker walls, chute sides, gravity spout surfaces, and conveyor beds. Sheets are fastened by bolts through countersunk holes (for zones of intense abrasion where the sheet must be replaced quickly) or bonded to the substrate (for zones of moderate wear where a continuous surface without holes is preferred). Sheet thickness is selected based on material particle size, drop height, and required service life.
Ready-made inserts are manufactured for the internal lining of pipes, chutes, elbows, and angular sectors. The insert is placed inside the pipe and secured by flanges without bonding, allowing it to expand independently of the metal when heated. This method is widely used for gravity chutes in grain handling: the polyurethane insert reduces grain losses by cushioning the impact of grain on metal and preventing build-up in the transition zone.
Hot adhesion creates the strongest bond between polyurethane and metal: the layer and substrate become a single system that expands and contracts together during temperature cycles. This method is used for shaft lining, finishing and pulling rollers, and equipment subjected to vibration and bending, where layer peeling under a flexural cycle must be excluded. Hot adhesion lining on shafts is described in more detail in the shaft coating article on the services page.
Material Comparison for Lining
| Material | Abrasion DIN 53516, mm³ | Operating t, °C | Density, g/cm³ | Tensile strength, MPa | Impact/noise damping | Corrosion resistance |
|---|---|---|---|---|---|---|
| Polyurethane TIMOL | 38-39 | -60…+100 | 1.05-1.25 | 39-87 | high | no corrosion |
| SBR rubber | 100-200 | -40…+80 | 0.94-1.1 | 8-20 | medium | no corrosion |
| Hardox wear steel | n/a | -40…+250 | 7.8-7.85 | 1250-1600 | poor | poor |
The table shows why polyurethane is preferred over both rubber lining and wear steel for conditions combining abrasion and impact. Rubber lining wears 4-8 times faster, is damaged by oil and petroleum product contact, and stiffens in frost outside the -40 °C lower limit. Hardox is very strong but 6-7 times heavier, does not damp impact, corrodes in a humid or acid environment, and amplifies noise rather than reducing it. Polyurethane delivers the best balance: among lining materials it has the lowest abrasion, highest impact damping, corrosion immunity, and the wide operating range from -60 to +100 °C.
Engineer’s tip: in bunker and chute lining, do not use a single uniform sheet thickness. In the impact zone — where lumps fall directly — specify greater thickness; on the sliding sections where material moves at angle without free fall, a thinner sheet is sufficient. This concentrates material where it is most needed, reduces cost, and equalises the actual wear rate across the lining so that all sections require replacement at the same time.
Applications Across 12 Industries
In mining, polyurethane lining protects bunkers, receiving chutes, crushing station transfer nodes, screen decks, and pipeline bends from ore and crushed stone abrasion. In metallurgy — bunkers for pellets and concentrates, chutes at rolling mill transfer nodes. In the chemical industry — tank linings resistant to aggressive media. In grain handling — chute inserts and gravity spout linings that reduce grain losses and eliminate dust from free-fall impact.
In the pulp and paper industry, polyurethane lining of rolls and press parts works in a continuously wet abrasive environment. In food production, food-grade polyurethane formulations line conveyor beds and processing equipment that contacts product. In the port and logistics sector, lining of ship hold loading equipment and port terminal chutes reduces abrasive losses and maintenance costs.
Across all these sectors the economic calculation is the same: the equipment itself — bunker body, chute, shaft — lasts for decades; the lining is a wear part replaced on a planned schedule. The cost of lining is several times lower than the cost of the equipment, so the switch from bare metal to polyurethane lining makes the operation more economical even at a premium over rubber. Industry-specific solutions are covered in the industries section; technical details in the reference information section.
How to Order Polyurethane Lining
To place a lining order, describe the equipment: bunker, chute, shaft, or other equipment with dimensions; the type of material being processed (ore, grain, concrete, chemical), particle size and drop height; and current wear conditions. Based on this data the factory selects the lining method, sheet or ring thickness, and hardness and formulation for the operating conditions.
TIMOL factory accepts both new equipment to be lined for protection and worn equipment to be restored. Factory and on-site work are both available. Both single-unit lining for equipment repair and supply of lining material for a production facility’s own maintenance team are possible. For consultation, method and thickness selection, and ordering, contact TIMOL factory. Engineers will propose the optimal lining solution and estimate service life for your operating conditions.