The grinding roller is the primary wear component of a vertical roller mill (VRM) — the rotating tire that crushes and grinds raw material against the grinding table. LIMING manufactures VRM rollers and segmented tires in Ni-hard and high chrome cast iron, with hardfacing and rebuild services to maximize service life.
In a vertical roller mill, two to four grinding rollers are pressed against a rotating grinding table by hydraulic cylinders. Raw material fed onto the table is caught between the rollers and the table surface, where it is crushed and ground by a combination of compression and shear forces. The ground material is then entrained by the upward air flow and conveyed to the classifier for separation.
The roller tire — the outer wear surface of the grinding roller — experiences the most severe wear in the entire VRM. It is in continuous contact with abrasive raw material (limestone, clinker, slag, coal) under high pressure. A worn roller tire loses its grinding profile, reducing mill output and increasing energy consumption. Regular inspection and timely replacement or refurbishment of roller tires is essential for maintaining VRM performance.
LIMING offers VRM roller solutions for all major vertical mill designs including LM (Loesche), OK, Atox, and MPS types. We supply both segmented tires (bolt-on segments that can be replaced individually without removing the roller assembly) and solid one-piece tires for mills with non-segmented designs.
The roller tire material determines the wear life and grinding efficiency. LIMING offers two primary material technologies, both engineered for extreme abrasion resistance:
| Material | Hardness (HRC) | Wear Resistance | Toughness | Best For |
|---|---|---|---|---|
| Ni-hard IV (Nickel-Hard Cast Iron) | 55-62 | Excellent | Good | General raw mill and cement mill service |
| High Chrome Cast Iron (Cr20/Cr26) | 60-66 | Outstanding | Moderate | Highly abrasive feed, slag grinding |
Beyond material selection, LIMING offers multiple wear protection options to extend roller tire service life:
Premium wear materials, hardfacing expertise, and complete roller lifecycle support.
Ni-hard IV and high chrome Cr26 tires engineered for maximum hardness and abrasion resistance.
In-house automatic welding restores worn roller profiles and deposits HRC 60+ wear layers.
Worn rollers restored to original profile at a fraction of new-roller cost — typically 40-60% savings.
Rollers and segments for LM, Atox, MPS, OK, TRM, and other VRM types — custom-engineered to your mill.
| Parameter | Specification |
|---|---|
| Product Type | VRM grinding roller / segmented tire |
| Material Options | Ni-hard IV, High chrome cast iron (Cr20/Cr26) |
| Design | Segmented tire (bolt-on) or solid one-piece |
| Roller Diameter | 1,000 mm – 3,000+ mm (per mill model) |
| Tire Width | 200 mm – 800 mm (per design) |
| Segment Count | 4-12 segments per roller (segmented design) |
| Hardness | HRC 55-66 (material dependent) |
| Hardfacing Layer | 5-15 mm overlay, HRC 60+ (optional) |
| Heat Treatment | Quench and temper, stress relief after hardfacing |
| Profile | Custom crown/taper matched to grinding table |
| Unit Weight | 500 kg – 10,000+ kg per roller/tire |
| Rebuild Service | Profile restoration, hardfacing, grinding to original dimensions |
| Lead Time | 30-60 days (new), 10-20 days (rebuild service) |
From casting to hardfacing — every step engineered for maximum wear life.
Custom patterns for the roller or segment profile. Ni-hard or high chrome cast into sand/lost-foam molds.
Quench and temper achieves target hardness (HRC 55-66) while maintaining adequate toughness.
CNC turning of the grinding profile, bolt holes, and mating surfaces to exact dimensions.
Optional automatic welding overlay deposited on the wear surface for extended service life.
Hardness testing, profile measurement, UT inspection, and dimensional verification before shipment.
Replacing VRM rollers entirely is expensive. LIMING's roller rebuild service restores worn rollers to original (or better) condition at a fraction of the cost of new parts. Our rebuild process includes:
Rebuilt rollers typically achieve 80-100% of new-roller service life at 40-60% of the cost. Most rollers can be rebuilt 2-3 times before the core requires replacement.