HPGR

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HPGR Maintenance & Tyre Change Expertise

CHS Mechanical Services Inc. brings extensive hands-on experience in the maintenance, overhaul, and component replacement of High Pressure Grinding Rolls (HPGR) in heavy mining applications. We understand the mechanical, hydraulic, and structural demands placed on these units and the importance of executing maintenance with precision to protect throughput and plant availability.

Our team has worked on both legacy segmented roll designs as well as modern HPGR configurations, including units originally manufactured prior to acquisition and later rebranded under the Enduron line. This background gives us a strong understanding of the evolution in roll assembly design, frame configuration, bearing arrangements, and hydraulic systems across generations of equipment.

We are highly experienced with the newer side-opening HPGR design, where complete roll assemblies are extracted laterally as a single unit. This process requires detailed planning, proper lifting procedures, precise rigging, and controlled disassembly to maintain frame integrity and bearing alignment. Our crew is proficient in complete tyre change-out procedures, roll extraction and reinstallation, bearing cartridge handling, hydraulic system reconnection, and post-installation verification.

Working within the correct site conditions and coordinated shutdown environment, our team can execute a complete roll change — from feed off to feed on — in as little as four days, while maintaining strict safety standards and mechanical tolerances.

With deep knowledge across multiple HPGR generations and configurations, CHS Mechanical Services Inc. delivers disciplined, technically sound maintenance solutions that minimize downtime and restore equipment to peak operating performance

During the initial phases of an HPGR roll change, it is critical that all hydraulic lines, lubrication lines, instrumentation, and electrical connections are meticulously labeled, capped, and protected from environmental exposure. The operating environment of an HPGR — particularly in mining and aggregate applications — can be extremely dusty, making contamination control a key component of a successful maintenance procedure.

Failure to properly identify and protect these systems can lead to debris intrusion, system contamination, premature component wear, and unnecessary troubleshooting during reassembly.

Thorough labeling and safeguarding not only protects system integrity but also significantly improves efficiency during reinstallation. Clear identification allows for streamlined reconnection of services, reducing downtime and supporting a smooth installation and startup of the new roll assemblies.

Attention to detail during preparation directly impacts reliability, performance, and overall project timeline

With the tyre safely positioned in the saddle, the controlled heating procedure can commence. CHS works closely with the equipment manufacturer to ensure the shaft is properly extracted from the wear component without compromising critical non-wear elements. Following the correct heating and extraction procedures is essential to preserving shaft integrity, bearing surfaces, and structural components so they can meet — and often exceed — their intended service life.

In this photo, significant washout can be observed within the base material of the tyre. HPGR tyres consist of a high-strength base material drilled with precisely sized ports designed to mechanically bond with tungsten carbide studs. These studs provide the hardened grinding surface required to process material to the desired specification.

Washouts typically occur when the autogenous protective layer on the roll surface fails to properly build and maintain itself. Correct machine parameters — including pressure, feed consistency, and operating conditions — are critical in establishing this protective layer and preventing premature exposure of the base material. When operated outside recommended parameters, localized wear can accelerate rapidly, leading to costly tyre replacements.

To further extend tyre service life, CHS has developed a repair process in collaboration with the manufacturer that allows us to rebuild washed-out areas and reinstall studs in affected zones. This repair strategy prevents localized heavy wear from spreading and compromising the structural integrity of the tyre, helping to maximize uptime and reduce overall operating costs.

Tyre changes represent a significant investment. Proper operating practices, disciplined maintenance procedures, and strategic repair methods are essential to protecting that investment and extending the life of your HPGR components.

The image above shows a tyre assembly, with the bearing cartridges removed, being carefully hoisted into the saddle to begin the removal of the worn tyre. This stage of the process requires precise rigging, controlled lifting procedures, and strict adherence to safety protocols.

HPGR tyre changes represent a significant operational investment and must be executed with accuracy and discipline. Specialized tooling, engineered lifting procedures, and experienced personnel are essential to prevent damage to critical components and ensure proper reinstallation.

Our team’s extensive knowledge and hands-on experience with HPGR systems ensures that each tyre change is completed safely, efficiently, and to manufacturer specifications — protecting your equipment, minimizing downtime, and supporting reliable machine performance

A common misconception we encounter across the industry is referring to an HPGR as a “crusher.” In reality, HPGR stands for High Pressure Grinding Rolls, and its function is fundamentally different. An HPGR is designed to operate as a grinding unit — not a primary crushing device.

For optimal performance, the material fed into the HPGR should already be properly sized by upstream crushing equipment within the circuit. When oversized material is introduced, it can negatively impact pressure distribution, stud wear, and overall machine efficiency.

Proper feed sizing allows the HPGR to operate within its intended parameters, maximizing grinding efficiency, extending component life, and maintaining consistent throughput. Most importantly, correct operation improves downstream mineral liberation, making extraction processes more efficient later in the circuit.

Understanding the role of the HPGR within the overall comminution process is critical to protecting the equipment, optimizing performance, and reducing long-term operating costs