I. The "Hot Shutdown Conundrum" of Bearing Replacement under High Temperature Conditions

In heating furnaces, rolling mills, continuous casting machines, rotary kilns in cement plants, melting furnaces in glass factories, electrolytic cells in aluminum smelting plants, and various heat treatment equipment, bearings are constantly exposed to extreme high temperatures ranging from 200 to 500 degrees Celsius or even higher. Ordinary bearing steel undergoes tempering softening and a sharp drop in hardness under high temperatures, and lubricating grease is carbonized and lost, significantly shortening the bearing's lifespan. Once a bearing fails, the maintenance team not only faces the difficulty of the replacement itself, but also encounters a fatal "hot shutdown conundrum" - traditional complete bearing replacements require the equipment to naturally cool from several hundred degrees to room temperature, a process that itself takes several days, and after the replacement, it takes several more days to reheat the equipment to the working temperature; moreover, the engineering workload of disassembling the shaft, the coupling, the reducer, and other surrounding components is even more severe.

 

Take the cement rotary kiln as an example: the surface temperature of the kiln body is as high as 200-400 degrees Celsius. The bearing on the support wheel operates under the radiation of high temperature and heavy load impact. When replacing the traditional complete bearing, it is necessary to first stop feeding, wait for the kiln body to cool down (2-3 days), disassemble the support wheel assembly, lift out the old bearing, install the new bearing, re-center it, and reheat it (2-3 days) - the entire replacement cycle lasts for more than a week. The production loss during this period is in the tens of millions of yuan, and the repeated heating and cooling cycles will cause irreversible thermal fatigue damage to the refractory materials of the kiln body, shortening the service life of the kiln lining.

 

Typical pain points of traditional complete bearings under high-temperature conditions:

 

Long cooling waiting time - The equipment needs several days to cool down from the operating temperature of 200-500 degrees Celsius to the operational temperature. The thermal stress during the cooling process may cause cracking and deformation of the refractory materials of the kiln body.

 

Long heating resumption cycle - After the bearing replacement, the equipment needs several days to reheat to the working temperature, and during this period, a large amount of energy is consumed.

 

Extremely large disassembly workload - Replacing a single bearing requires disassembling the coupling, gears, reducer, frame, and other surrounding components.

 

Cumulative thermal fatigue damage - Each shutdown and cooling process causes thermal fatigue damage to the kiln body, refractory materials, and equipment structure.

 

Risk of secondary damage to the shaft neck - Under high-temperature conditions, the metal expansion coefficient changes, making disassembly more difficult and the risk of shaft neck damage higher.

 

Harsh working environment - The residual heat around the high-temperature equipment remains, and the working conditions of maintenance personnel are extremely difficult, with significant safety hazards.

 

II. NMT High-Temperature Split-Type Bearing: No Shutdown During Hot Operation, Quick Replacement During Cold Operation

The NMT high-temperature split-type bearing combines the core advantage of "bearing installation without disassembly of the shaft" of split-type bearings with the outstanding performance of high-temperature-resistant steel that "resists tempering softening". The inner ring, outer ring, rolling elements, and cage of the bearing are split axially, and during installation, there is no need to disassemble any core components such as the main shaft, coupling, and gearbox, and the assembly can be completed directly at the original position of the shaft. More importantly - the NMT high-temperature split-type bearing can complete the replacement of the bearing even when the equipment has not cooled down to room temperature, significantly compressing the waiting time in the "cooling - replacement - heating" long process.

 

▸ Full split + high-temperature-resistant structure: Each piece can "split apart and move, rotate together", and can withstand high-temperature tests

 

Each component of the NMT high-temperature split-type bearing is split - split the inner ring, split the outer ring, split the cage with rolling elements, and split the sealing components. During installation, these semi-ring components are assembled around the shaft in sequence, locked and fixed with high-strength heat-resistant bolts, and form a precise transmission unit that is completely consistent with the performance of the complete bearing. The split interface adopts a precise stepped对接 structure or V-shaped split opening design to ensure that the assembled bearing has no less precision in bearing and rotation than the complete bearing. In terms of material, NMT offers a complete high-temperature steel system - carburized heat-resistant bearing steel undergoes special heat treatment to maintain a balance of hardness and toughness in a high-temperature environment, resisting thermal softening and creep; for ultra-high temperature conditions above 500°C, high-temperature alloy steel or special heat-resistant stainless steel can be selected. Combined with a heat-stabilization treatment process, internal stress in the material is eliminated, ensuring the size stability of the bearing during repeated temperature rise and fall cycles. The raceways and rolling elements are precisely ground, maintaining low friction and low vibration operation characteristics at high temperatures.

 

▸ No disassembly for installation: in-situ replacement, without moving any surrounding equipment, no need for complete cooling

 

The core value of NMT's high-temperature split bearings lies in that replacing the bearing does not require moving the shaft, and there is no need to wait for the equipment to cool completely. This means that the coupling does not need to be disassembled, gears do not need to be disassembled, the reducer does not need to be moved, and the frame does not need to be disassembled. Maintenance personnel only need to wait until the equipment cools to a safe operating temperature (usually much higher than normal temperature), open the bearing housing, remove the half ring of the old bearing, install the half ring of the new bearing, lock the bolts, and then start to reheat and resume production. Throughout the process, the original assembly structure, dynamic balance state, and furnace heat state of the equipment are maximally preserved.

 

▸ Interchangeable with standard high-temperature integral bearings: seamless replacement, no need for modification

 

The design of NMT's high-temperature split bearings fully considers interchangeability with standard high-temperature integral bearings. In most cases, the outer diameter, outer ring width of the split bearings are exactly the same as those of standard self-aligning roller bearings (222, 230, 231, 239, 240, 241 series). This means that customers can directly replace the existing integral bearings in the equipment with NMT's high-temperature split bearings without any mechanical processing of the bearing housing.

 

III. Compatibility with a full range of high-temperature split bearing types

NMT provides a split bearing product system covering various high-temperature working conditions:

 

▸ High-temperature split cylindrical roller bearings

 

Carrying high radial loads with heat-resistant steel cylindrical rollers. The inner ring, outer ring are each divided into two halves, and the cage with one or two rows of cylindrical rollers is also split. The outer ring can have flanges to withstand limited axial thrust, providing "fixed end" and "floating end" configurations. Suitable for high-temperature heavy-duty radial applications such as conveyor belts for heating furnaces, fan-shaped sections of continuous casting machines, and conveyor belts for heat treatment furnaces.

 

▸ High-temperature split self-aligning roller bearings

 

Designed for the requirements of shaft deflection deformation and thermal expansion compensation in high-temperature environments. The inner ring, outer ring and the cage with rollers are all split into two halves. Its self-aligning performance is the same as that of integral self-aligning roller bearings, effectively compensating for the deflection deformation or installation errors of the shaft under high-temperature conditions. Suitable for rotary kiln supports, rolling mills, ball mills, high-temperature fans, etc., under heavy-load impact and high-temperature conditions.

 

▸ High-temperature split conical roller bearings

 

Two rows of heat-resistant steel conical rollers can simultaneously bear radial and bidirectional axial loads. Suitable for fixed-end bearing positions requiring combined loads. Designed for applications such as metallurgical rolling mills, continuous casting equipment, high-temperature pumps, etc.

 

IV. Special sealing and lubrication systems - compatible with high-temperature, high dust, and heat radiation environments

Metallurgical and heat treatment equipment is often in harsh working conditions of high temperature, high dust, and strong heat radiation. NMT's high-temperature split bearings are paired with dedicated sealing and lubrication systems:

 

▸ High-temperature labyrinth seal structure - non-contact design, using rotational centrifugal force to expel high-temperature dust, hot air, and impurities, avoiding failure caused by the aging of sealing components under high temperatures.

 

▸ Upgrade of heat-resistant contact seal - for high-dust, high-heat radiation environments (such as cement rotary kilns, rolling mills), NMT provides a heat-resistant contact seal solution, using FKM or silicone rubber materials, capable of withstanding temperatures above 200°C.

 

▸ Solid lubrication and high-temperature lubricating grease solutions - traditional lubricating grease quickly carbonizes and loses in high-temperature conditions. NMT offers a graded lubrication solution: special high-temperature composite grease is used for conditions up to 200-300°C; solid lubricants (graphite, molybdenum disulfide) or ceramic self-lubrication solutions are used for conditions above 300°C.

 

▸ Split-type seals - The seals also adopt a split structure, allowing for installation without removing the shaft, and completing assembly synchronously with the bearing.

 

V. Installation and Maintenance - Efficiency Revolution from "Weeks" to "Hours"

Installation time comparison:

 

Traditional high-temperature integral bearings: downtime for cooling (2-5 days) → disassembly of coupling, gears, reducer, frame → moving the shaft → inserting the bearing → re-centering → re-assembly → re-heating (2-5 days). The typical duration is 1-2 weeks.

 

NMT high-temperature split-type bearings: equipment is cooled to an operable temperature (usually within 1 day) → opening the bearing housing → removing the old half-ring → installing the new half-ring → tightening the bolts → re-heating. The typical duration is only a few hours to 1 day.

 

NMT high-temperature split-type bearings can reduce the downtime for bearing replacement of high-temperature equipment by 80-90%. For example, replacing the bearing of a cement rotary kiln support wheel: traditional integral bearings require a 7-10-day shutdown; with the high-temperature split-type bearing solution, the replacement can be completed in 1-2 days, saving nearly a week of unplanned downtime.

 

Maintenance convenience:

 

Hot-state replacement is feasible - no need to wait for the equipment to cool down to room temperature, significantly shortening the downtime period.

 

Can be inspected at any time - no disassembly required to open the bearing housing to check the operating condition of the bearing.

 

Split transportation - the bearing can be split into smaller components, simplifying the lifting and transportation tasks.

 

No on-site adjustment - the clearance is preset at the factory, no on-site adjustment or special installation tools are required.

 

VI. Quality Control - Triple Guarantee of High Temperature Performance, Split Precision and Thermal Stability

NMT implements a strict quality control system for high-temperature split-type bearings:

 

Heat-resistant material certification - each batch of heat-resistant steel undergoes high-temperature hardness testing and thermal stability verification to ensure performance meets the target working temperature.

 

Thermal stabilization treatment - the bearings undergo multiple rounds of high-temperature tempering and stabilization treatment to eliminate internal stress, ensuring dimensional stability in repeated temperature rise and fall cycles.

 

Precision machining of split surfaces - high-precision wire-cutting process is used to machine the inner and outer ring split surfaces to ensure concentricity and strength after assembly.

 

High-temperature clearance preset - precise preset of thermal state clearance based on different working temperatures to ensure the optimal operating clearance after high-temperature expansion.

 

Assembly accuracy inspection - each set of split-type bearings is inspected for radial clearance, rotational accuracy and vibration values after assembly to ensure consistency with integral bearings.

 

VII. Stock Availability + Non-standard Customization - Rapid Response to High-Temperature Equipment Emergency Needs

Common high-temperature split-type bearing models (high-temperature split-type cylindrical roller bearings, high-temperature split-type self-aligning roller bearings) are in stock - covering 80% of the high-temperature split bearings in the steel, cement, glass, aluminum smelting, and heat treatment industries. Quick response to emergency failures, minimizing unplanned downtime.

 

Customization projects - special inner and outer diameters/widths (standard range 55mm to 630mm, expandable), custom heat-resistant materials (carburized heat-resistant steel/high-temperature alloy steel/special heat-resistant stainless steel), special split structures, custom sealing solutions (high-temperature labyrinth/heat-resistant contact type), custom thermal state clearance, solid lubrication solutions.

 

Customization based on old bearings or drawings - providing old bearing samples or equipment drawings, NMT can quickly complete mapping and custom production. Affordable replacement of imported brands (SKF Cooper, FAG, NSK), significantly reducing procurement costs.

 

VIII. Full Life Cycle Cost Optimization - No Shutdown for High-Temperature, No Cooling for Axle Replacement

Unplanned shutdowns of high-temperature equipment often result in losses in the tens of millions of yuan. Take the replacement of the bearing of the cement rotary kiln support wheel as an example: the total cost of the traditional integrated bearing solution is as high as several hundred million yuan (bearing + manual installation + cooling wait + temperature rise resumption + refractory material thermal fatigue repair + shutdown loss); while adopting the high-temperature split bearing solution, the total cost is reduced by more than 60%, saving several hundred million yuan each time.

 

The hidden costs of low-priced ordinary high-temperature integrated bearings:

 

Each replacement requires a shutdown of 1-2 weeks, and the shutdown loss is hundreds of times the price of the bearing.

 

Consuming huge amounts of energy during cooling and re-heating.

 

Repeated temperature rise and fall cause cracking of the refractory materials in the furnace body, and the repair cost is high.

 

Axle neck damage during disassembly, and the repair cost is also high.

 

The working conditions in high-temperature environments are harsh, and the labor cost surges.

 

The lifespan of ordinary high-temperature bearings is limited under extreme high temperatures, and frequent replacements exacerbate the above losses.

 

NMT high-temperature split bearings achieve "one-time installation, worry-free for many years; high-temperature no shutdown, axis replacement without cooling" in rotary kilns, heating furnaces, rolling mills, heat treatment equipment, etc. high-temperature working conditions:

 

The downtime is shortened by 80-90% - from weekly to hourly/day level, and the annual unplanned shutdown loss is significantly reduced.

 

No need for complete cooling for replacement - significantly shortens the cooling wait and re-heating time, reducing energy waste.

 

Heat-resistant steel resists high-temperature softening and creep - maintaining hardness and toughness balance at 200-500℃ high-temperature environment.

 

No need to disassemble the shaft for installation, eliminating axle neck damage - avoiding磕碰磨损 during disassembly and installation process from the root.

 

Reduced thermal fatigue damage - avoiding damage to the furnace body refractory materials and equipment structure caused by repeated temperature rise and fall.

 

The lifespan of supporting equipment (gears， couplings， reducers) is extended - reducing the number of disassemblies， and the overall overhaul cycle of the machine is prolonged.

 

For steel enterprises， cement plants， glass manufacturing enterprises， aluminum smelting plants， and heat treatment processing enterprises， the comprehensive holding cost of NMT high-temperature split bearings is much lower than the repeated disassembly cost of traditional high-temperature integrated bearings - what is saved is not the difference in bearing prices， but the huge operational risks of "changing one bearing， shutting down one production line， and burning one furnace lining" for high-temperature equipment.