Vertical roller mill grinding roller tire - cylindrical ring shape high chromium casting with red protective coating and precision machined inner bore - ZHILI foundry

Grinding Roller / Roller Tire ISO 9001:2015 SSAB Hardox Authorized

Grinding Roller / Roller Tire

VRM Grinding Roller Segments & Roller Tires — Ni-Hard IV / High Chrome Alloy (Cr20 / Cr26 / Cr27Mo2) / Hardfaced Composite — For Loesche / Pfeiffer / FLSmidth Atox / Polysius / UBE

Material Ni-Hard IV / High Chrome Cast Iron (Cr20 / Cr26 / Cr27Mo2) / Hardfaced Composite / Bi-Metallic Steel

Hardness HRC 55-62 (Ni-Hard/High Cr As-Cast) / HRC 63-68 (Hardfaced Surface) — designed for rolling-abrasive wear

Compatibility Loesche LM Series / Pfeiffer MPS / FLSmidth Atox & OK / Polysius RM / UBE / Sinoma / Citic / NHI / Chaeng

Certification ISO 9001:2015 Certified, EN 10204 3.1 Mill Test Certificate, NDT Report (UT/MT)

30+ Years of Manufacturing

500+ Global Clients

15 Days Lead Time

NO MOQ Custom OEM/ODM

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Grinding Roller / Roller Tire — Material Specifications | ZHILI

Grade	Material	Hardness	Carbide	Life Factor	Application
Ni-Hard IV	Ni4-Cr8 (ASTM A532)	55-60 HRC	20-28%	1.0x	Coal, raw meal, moderate wear
High Cr Cr20	Cr18-22% + Mo	58-62 HRC	25-33%	1.3-1.5x	Cement raw meal, standard duty
High Cr Cr26	Cr23-28%	58-63 HRC	28-38%	1.5-1.8x	Slag grinding, high silica
Cr27Mo2	Cr26-29% + Mo1.5-2.5%	58-65 HRC	30-42%	1.8-2.2x	Cement clinker, high temp
Ceramic Insert	ZTA / Al2O3 + Cr matrix	62-68 HRC	40-50%	2.5-3.5x	Silica-rich ore, extreme wear

Component	Material	Hardness	Process	Feature
Surface Ring	High Cr White Iron	58-65 HRC	Centrifugal cast	Carbide-rich wear surface
Bonding Layer	42CrMo + Ni-Based	35-42 HRC	Interfacial fusion	Metallurgical bond to core
Roller Core	35CrMo / 42CrMo	28-35 HRC	Forged + Q+T	High toughness, fatigue resist
Shaft	40Cr / 42CrMo	28-32 HRC	Forged + tempered	Torque transmission
Bearings	GCr15 (KOYO/NSK)	58-64 HRC	Through-hardened	Heavy-load cylindrical

VRM Brand	Model	Roller Dia.	Width (mm)	Material	Rec. Grade
Loesche	LM 28.3D	1,900	650	High Cr White Iron	Cr20
Loesche	LM 46.4	3,100	1,050	High Cr White Iron	Cr26
Loesche	LM 56.3+3 CS	3,800	1,250	High Cr + Ceramic	Cr27Mo2
Pfeiffer	MPS 3750 B	2,200	750	High Cr White Iron	Cr20
Pfeiffer	MPS 4750 B	2,650	920	High Cr White Iron	Cr26
Pfeiffer	MPS 5600 BC	3,100	1,100	High Cr + Ceramic	Cr27Mo2
FLSmidth	Atox 35	2,200	700	High Cr White Iron	Cr20
FLSmidth	Atox 50	3,000	980	High Cr White Iron	Cr26
FLSmidth	OK 42-4	2,600	850	High Cr White Iron	Cr26
Polysius	RM 41/19	2,400	800	High Cr White Iron	Cr20
Polysius	RM 54/27	3,100	1,050	High Cr White Iron	Cr26
UBE	UM 38.4	2,700	900	High Cr White Iron	Cr26
UBE	UM 50.4	3,500	1,200	High Cr + Ceramic	Cr27Mo2
Sinoma	TRM 38.4	2,700	900	High Cr White Iron	Cr20/Cr26
Sinoma	TRM 53.4	3,700	1,250	High Cr + Ceramic	Cr27Mo2

Selection Quick Reference

Coal mill grinding roller (lower abrasion, moderate temp): Ni-Hard IV or Cr20 — most economical for coal and petcoke grinding, roller diameter 1,900-2,400 mm, service life 15,000-22,000 hrs
Raw meal grinding roller (limestone + clay, standard abrasion): Cr20 standard; upgrade to Cr26 for hard limestone with chert/flint, roller diameter 2,200-3,100 mm, life 12,000-18,000 hrs
Slag grinding roller / GGBFS (high silica, 30-35% SiO2): Cr26 minimum, Cr27Mo2 preferred for >200 tph — requires hardfacing rebuild every 2,000-3,000 hrs on roller surface
Cement finish grinding roller (250-350 C, clinker + gypsum): Cr27Mo2 with Mo content >1.5% essential for hot hardness retention at elevated operating temperatures
Silica-rich ore grinding (quartz, extreme abrasion): Ceramic insert (ZTA/Al2O3) in high Cr matrix — 2.5-3.5x life vs standard high Cr, for severely abrasive applications

Certifications & Authorizations

Quality you can verify. Partners you can trust.

National Invention Patent Certificate — Multi-hammer Sand Mold Casting Process — Luoyang Zhili ZL 2016 1 0056588.5

ISO 9001:2015 Quality Management System Certificate — Luoyang Zhili New Materials — GICG UK Certified IAF Accredited Valid until 2027

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Grinding Roller / Roller Tire — FAQ | ZHILI

Frequently Asked Questions

1 How long do VRM grinding rollers last, and what is the most common failure mode?

Unlike crusher wear parts that fail by pure abrasion, VRM grinding rollers fail primarily through rolling contact fatigue combined with abrasive wear. The roller experiences cyclic compression every revolution, creating sub-surface shear stress that leads to material spalling (flaking off in large pieces).

Coal Mill

15,000-20,000 hrs

Raw Meal

10,000-15,000 hrs

Slag (GGBFS)

6,000-10,000 hrs

Cement Clinker

8,000-12,000 hrs

Three main failure modes:

Surface wear (normal): Gradual abrasive wear by the material bed. Managed by hardfacing rebuild every 2,000-5,000 hours depending on material grade and feed abrasiveness.
Spalling (fatigue): Sub-surface cracks propagate parallel to the surface, causing chunks to flake off. Most common in brittle materials like Ni-Hard IV. Cr27Mo2 with tempered martensite matrix reduces spalling risk by 60-70% vs Ni-Hard.
Catastrophic fracture: Radial cracking from tramp metal impact or thermal shock. The hard Cr grades are brittle — if your feed contains occasional tramp iron, a bi-metallic roller (Mn13Cr2 core + Cr26 outer shell) is the safest choice.

Uneven wear pattern: The roller leading edge typically wears 30-40% faster than the trailing edge due to higher contact pressure on material entry. Our profile restoration rebuild restores the original OEM contour within +/- 1.0mm.

2 What hardfacing and rebuild options does ZHILI offer for VRM rollers? Can you do on-site repair without removing the roller?

Yes. ZHILI offers three rebuild service levels specifically engineered for VRM grinding rollers:

1. On-Site Roller Rebuild (Mobile Service)

Our team deploys to your plant with a powered roller turning device that rotates the roller at controlled 0.5-1.5 m/min surface speed for uniform overlay deposition — this is critical because uneven hardfacing causes out-of-round vibration.
Hardfacing applied inside the mill without removing the roller assembly. Typical rebuild time: 18-36 hours per roller.
Standard Fe-Cr-C or premium Nb/WC-reinforced flux-cored wire. Single or double pass, 3-8mm total buildup.
Includes preheat to 250-300 C (gas burner or induction), interpass temperature control, and controlled cool-down.

2. Workshop Full Rebuild (Factory Quality)

Roller removed and shipped to our facility. Full process: UT/MT inspection, crack gouging and repair welding, 300-400 C preheat, multi-layer robotic overlay (6-axis robot, +/-0.3mm uniformity), post-weld stress relief heat treatment, CMM dimensional check within +/- 1.0mm.
Includes complete documentation: NDT report, overlay chemistry, dimensional report, EN 10204 3.1.

3. Profile Restoration (Uneven Wear Correction)

Specialized rebuild for rollers with uneven leading-edge-to-trailing-edge wear. Restores the original OEM profile (convex, flat, grooved) within 0.5mm deviation across the roller width. This restores even grinding pressure distribution and prevents vibration.

Which option? On-site = fastest (18-36 hrs/roller, zero removal). Workshop = highest precision (+/-1.0mm). Profile Restoration = best for rollers with uneven wear pattern. Our engineers help evaluate based on remaining roller thickness, wear pattern, and production schedule.

3 How do I choose between Ni-Hard IV, Cr20, Cr26, and Cr27Mo2 for my VRM grinding rollers?

Roller material selection is driven by feed abrasiveness, operating temperature, and failure mode tolerance. Here is the decision flow:

Coal / Petcoke

Ni-Hard IV

Standard Raw Meal (SiO2 <8%)

Cr20

Hard Raw Meal / Slag (SiO2 8-20%)

Cr26

Cement Clinker / Ultra-Abrasive (SiO2 >20%)

Cr27Mo2 + Hardfacing

Three factors unique to rollers (not applicable to grinding tables):

Spalling risk vs wear rate trade-off: Ni-Hard IV is cheap and has decent wear resistance, but its brittle M3C carbide structure makes it prone to spalling under cyclic rolling loads. Cr27Mo2 with tempered martensite matrix costs 1.5-2x more but reduces spalling failure risk by 60-70%. If a roller spalls catastrophically, the replacement cost ($15,000-60,000 per roller) plus 3-5 days downtime far exceeds the material cost difference.
Hot hardness requirement: Cement finish mills operate at 280-350 C. Ni-Hard IV softens significantly above 250 C; Cr27Mo2 retains hardness to 450 C. Always choose Cr27Mo2 for clinker grinding, regardless of SiO2 content.
Master/slave roller pairing: Mills with master + slave rollers (e.g., Loesche 3+3, Pfeiffer MVR) should use matched material pairs. Uneven wear between the pair causes vibration and uneven grinding pressure. ZHILI supplies weight-matched roller sets (difference < 0.5%) with identical material grade and heat treatment batch.

ZHILI recommendation: For new installations, we recommend starting with Cr26 (good balance of cost and performance) and evaluating wear rate over the first 6 months. Upgrade to Cr27Mo2 + hardfacing if annual roller consumption exceeds 2 sets. For plants already running Ni-Hard and experiencing spalling, switching to Cr26 typically reduces roller-related downtime by 40-50%.