Product Category

　 　High-chromium molybdenum alloy casting, hardness HRC 60–65
　　 Product Highlights
　　1. High-chromium molybdenum alloy cast iron material, with a Cr content of 24–28%, hardness of HRC 60–65, M₇C₃ carbide hardness of HV 1800–2200, and excellent wear resistance.
　　2. The roll sleeve can be replaced independently; the grinding roll consists of a roll sleeve, roll core, bearings, and a sealing system. As the roll sleeve is a wear part, it can be replaced separately after wear without replacing the entire assembly, resulting in low maintenance costs.
　　3. Compatible with mainstream medium-speed coal mills such as ZGM, HP, and MPS series; supports custom designs based on provided drawings to meet the requirements of different mill models and operating conditions.
　　 User Pain Points
　　The grinding rollers (roller sleeves) and bowl liners (grinding rings) of medium-speed coal mills are the core grinding components, crushing raw coal into powder through compression. Both are highly wear-resistant castings that must be used as a matched pair; unsynchronized wear leads to increased vibration and reduced pulverizing quality. Traditional rollers suffer from three major drawbacks: ① Conventional material roller sleeves lack sufficient wear resistance, requiring frequent replacement and resulting in significant downtime losses; ② Asynchronous wear between roller sleeves and bowl liners exacerbates equipment vibration and reduces grinding efficiency; ③ Replacing the roller sleeves necessitates complete disassembly of the assembly, leading to long maintenance times and high labor costs.
　　 Solution
　　Our company’s grinding rollers are made from KmTBCr26 high-chromium molybdenum alloy cast iron, containing 23–30% chromium, with a hardness of HRC 60–65. The microstructure features M₇C₃ carbides exhibiting a Vickers hardness of 1800–2200, providing excellent wear resistance. The roller shell is an independent wear part that can be replaced separately after wear, eliminating the need to disassemble the roller core or the bearing assembly, thus ensuring convenient maintenance. Our products are compatible with mainstream coal mill series such as ZGM, HP, and MPS, and we also offer custom manufacturing based on customer-provided drawings.
　 　I. Product Description
　　The grinding roll (roll shell/roll sleeve) is the core grinding component of a medium-speed coal mill, crushing raw coal into powder through compression. Its structure comprises a high-chromium cast iron roll sleeve, roll core, bearings, and a sealing system; the roll sleeve is a wear part that can be replaced independently. The standard material is KmTBCr26 high-chromium molybdenum alloy cast iron, containing 23–30% Cr with a hardness of HRC 60–65. High-end products utilize a metal-ceramic composite process, achieving a service life exceeding 18,000 hours. These rolls are widely applicable to mainstream medium-speed coal mill series such as ZGM, HP, and MPS.
　　 II. Product Specification Sheet

　　BTMCr26 is the recommended material for this product; please send us your drawings for a quotation.
　　 III. Product Features and Advantages
　　• High-chromium molybdenum alloy, wear- and impact-resistant: Made from KmTBCr26 high-chromium molybdenum alloy cast iron with a Cr content of 23–30% and a hardness of HRC 60–65. Its microstructure contains M₇C₃ carbides with a hardness of up to HV 1800–2200, providing exceptional resistance to abrasive wear. Under standard operating conditions, the roller shell has a service life of ≥8,000 hours or can process ≥120,000 tons of raw coal.
　　• Metal–ceramic composite technology (optional): High-end models utilize metal–ceramic composite technology, enabling roller sleeve lifetimes of over 18,000 hours and significantly reducing replacement frequency and downtime losses.
　　• Independent replacement for easy maintenance: The roll sleeve is a separate wear part; when worn, only the sleeve needs to be replaced without disassembling the roll core or bearing assembly, reducing maintenance complexity and spare-part costs.
　　• Compatible with mainstream models: Widely compatible with popular medium-speed coal mills such as ZGM (e.g., ZGM95/113/133), HP (e.g., HP94/103/116), and MPS (e.g., MPS190/225), and supports custom manufacturing based on customer-provided drawings.
　　• Paired use ensures synchronized wear: The grinding roller and the grinding disc pad are used as a matched pair, and the synchronization of their wear directly affects equipment vibration and powder quality. Our company can supply both the grinding roller and the grinding disc pad, ensuring precise matching and operational stability.
　 　IV. Why Choose Us
　　• Premium Raw Materials: We rigorously select high‑quality scrap steel free of rust and oil, along with chromium‑molybdenum alloy additives, to ensure purity at the source. This guarantees that the grinding rolls (roll sleeves) are dense and free of harmful impurities, laying a solid foundation for exceptional hardness and impact‑resistant toughness.
　　• Ultimate Density: Combining ceramic sand with a large-diameter heating riser process, this design effectively eliminates shrinkage porosity and cavities, ensuring a uniform and dense microstructure within the grinding roller and enabling it to withstand the high‑load crushing conditions of coal mills without cracking.
　　• Precision melting: Melting is performed using a Fuji electric furnace from Japan, with real-time compositional verification via a Bruker spectrometer from Germany. The content of key wear-resistant elements such as Cr and Mo is precisely controlled to ensure that the grinding roll hardness meets specifications (HRC 60–65).
　　• Flawless Casting: Employing a 850°C bake‑out and bottom‑pouring process, this method significantly reduces sand‑hole defects, ensuring a smooth, defect‑free working surface on the grinding roll and preventing stress concentrations that could lead to premature failure.
　　• Strengthened metallography: By optimizing the heat treatment process and air‑cooling normalizing control, a uniformly distributed M₇C₃ carbide microstructure is achieved, ensuring that the grinding roll exhibits both high hardness and impact toughness, with a service life of ≥8,000 hours under standard operating conditions.
　　• Powerful shot blasting: simultaneously removes surface sand and hardens the surface, revealing the metal’s natural luster and further enhancing the wear resistance of the grinding roller’s working surface.
　　• Rigorous quality control: Dual‑dimensional inspection via manual measurement and 3D scanning, with hardness tested on each individual component, ensuring precise fit between the grinding roller and the grinding disc to prevent equipment vibration caused by uneven wear.
　　• Transparent delivery: Scan a code to track production progress in real time, with full visibility from material input to shipment, ensuring greater peace of mind for bulk deliveries.
　　 V. Production and Quality Assurance
　　• Melting: Fully automatic digital control of the IGBT medium-frequency induction furnace ensures that the grinding rolls meet customer specifications.
　　• Composition Control: Dual-spectrometer synergy ensures that key elements such as Cr and Mo meet specifications in every batch.
　　• Heat treatment: Air cooling normalizing to obtain a uniformly distributed M₇C₃-type carbide microstructure, ensuring hardness and wear resistance.
　　• Dimensional Inspection: A coordinate measuring machine is used to verify the critical dimensions of the roller sleeve, ensuring installation accuracy and operational stability.
　　• Hardness testing: Hardness is tested on a per-piece basis, with HRC 60–65 meeting the specification.
　　• Full-process traceability: Each batch is accompanied by material reports, hardness reports, and dimensional reports.
　　 VI. Frequently Asked Questions (FAQ)
　　Q1: What material is recommended for grinding rollers?
　　We recommend BTMCr26 high-chromium molybdenum alloy cast iron, with a Cr content of 23–30%, a hardness of HRC 60–65, and excellent wear resistance. We can also provide other material options, such as BTMCr20, tailored to specific operating conditions.
　　Q2: After the roller sleeve is worn, is it necessary to replace the entire assembly?
　　No, it is not necessary. The roller sleeve is a separate wear part; when worn, only the sleeve needs to be replaced, while the roller core and bearing assembly can remain in service.
　　Q3: Which coal mill models are applicable?
　　Widely applicable to mainstream medium-speed coal mills such as ZGM, HP, and MPS series.
　　Q4: Can non-standard specifications be customized?
　　Customization based on provided drawings is supported, with production tailored to the coal mill model and operating conditions.
　　Q5: What is the minimum order quantity?
　　Negotiable; bulk purchases qualify for discounted pricing.
　　Q6: What is the delivery time?
　　Customization based on your drawings takes 45–60 days; expedited service is available upon negotiation for urgent orders.