I. The "Impossible Triangle" of Bearing Replacement for Large Heavy-Duty Equipment

In large heavy-duty equipment such as steel converters, ball mills in mines, cement rotary kilns, ship propulsion systems, and paper drying cylinders, the bearings are the key components that support the core shaft system's operation. However, once the bearings in these equipment fail, the maintenance team often faces an "impossible triangle" - the bearings cannot be replaced without disassembling the shaft, and disassembling the shaft requires dismantling the coupling, reducer, gears, and frame, which means days or even weeks of unplanned downtime.

 

Take the 300-ton converter of a large steel mill in North China as an example. When the ear shaft bearing (with an outer diameter of 1850mm and a total weight of over 5 tons) needed to be replaced, the original design used a monolithic self-aligning roller bearing. Before replacement, the drive large gear and part of the reducer had to be removed. Due to the narrow installation space of the ear shaft, the large number of surrounding components, and their heavy weight, the entire replacement project took an extremely long time and resulted in a shutdown loss of several million yuan.

 

Typical pain points of traditional monolithic bearings in large equipment:

 

Extremely large assembly and disassembly workload - Replacing a single bearing requires disassembling a large number of surrounding components such as couplings, gears, reducers, and frames, making the process cumbersome and extremely difficult.

 

Risk of secondary damage to the shaft neck - Frequent disassembly and assembly processes can easily cause scratches, wear, and deformation of the main shaft shaft neck due to forced pulling and knocking. The repair cost is extremely high.

 

Damage to dynamic balance accuracy - The main shaft of a large machine has been precisely balanced, and the overall disassembly and assembly can easily damage the original balance accuracy, causing vibration and abnormal noise in the equipment.

 

Downtime measured in days - The replacement time of traditional monolithic bearings is usually calculated in days or even weeks, resulting in huge production losses.

 

Limited installation space - The bearings of large equipment are often located in narrow and difficult-to-reach spaces. Traditional bearings simply cannot be installed in the current construction site.

 

II. NMT Split-Type Bearings: Open it, Install it, That's All

NMT split-type bearings completely overturn the traditional installation logic of "bearing must be inserted from the shaft end". The inner ring, outer ring, rolling elements, and cage of the bearing are split along the axial direction into two halves. During installation, there is no need to dismantle any core components such as the main shaft, coupling, gearbox, etc., and the assembly can be completed directly at the original position of the shaft.

 

▸ Full Split Structure: Each component can "split apart and rotate together"

 

Each component of the NMT 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 bolts, and form a precise transmission unit with the performance of the entire bearing. The split interface adopts a precise stepped对接structure to ensure that the assembled bearing has no worse bearing accuracy than the entire bearing.

 

▸ No need to disassemble the shaft for installation： In-place replacement， without moving any surrounding equipment

 

The core value of NMT split-type bearings lies in - replacing the bearing does not require moving the shaft. This means that the coupling does not need to be disassembled， the gears do not need to be moved， the reducer does not need to be disassembled， and the frame does not need to be disassembled. Maintenance personnel only need to open the bearing housing， remove the half ring of the old bearing， install the half ring of the new bearing， lock the bolts， and complete the process. The entire process can be completed without changing the original assembly structure and dynamic balance state of the equipment.

 

▸ Seamless replacement without modification： Interchangeable with standard monolithic bearings

 

NMT split-type bearings are designed to fully consider interchangeability with standard monolithic bearings. In most cases， the outer diameter and outer ring width of the split-type bearing are exactly the same as those of the standard self-aligning roller bearings (222， 230， 231， 239， 240， 241 series). This means that customers can directly replace the existing equipment's monolithic bearings with NMT split-type bearings without any mechanical processing of the bearing housing. III. Compatibility with a Full Range of Split Bearing Types

NMT offers a split bearing product system covering various operating conditions:

 

▸ Split cylindrical roller bearings

 

The most classic type of split bearing, which uses cylindrical rollers to bear high radial loads. The inner and outer rings are each divided into two halves, and a 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. They are suitable for conveyor belts, fans, cooling beds, continuous casting machines, etc., for heavy-duty radial applications.

 

▸ Split self-aligning roller bearings

 

Designed for scenarios requiring automatic self-aligning compensation for shaft deflection and installation deviations. The inner ring, outer ring, and the cage with rollers are all split into two halves. The split bearing ring is fixed together by high-strength bolts. Most split self-aligning roller bearings have an internal design derived from the verified standard self-aligning roller bearing E1 series. They are suitable for blast furnace ear shafts, ball mills, crushers, rotary kilns, etc., for heavy-duty impact conditions.

 

▸ Split conical roller bearings

 

Two rows of opposite conical rollers can simultaneously bear radial and bidirectional axial loads. They are suitable for fixed-end bearing positions that need to withstand combined loads. They are specifically designed for ship propulsion systems, conveyors, stacker reclaimers, etc.

 

IV. Special Sealing Systems - Compatible with Harsh Environments with High Dust and High Humidity

Large heavy-duty equipment is often in harsh working conditions with high dust, high humidity, and many impurities. NMT split bearings are paired with exclusive multi-sealing systems:

 

▸ Radial groove sealing structure - Non-contact design, using rotational centrifugal force to expel dust, water vapor, and impurities, avoiding failure due to wear of sealing components.

 

▸ Contact sealing upgrade - For high-dust, high-humidity environments (such as mines, cement, papermaking), NMT provides customized contact sealing solutions to effectively block dust, water vapor, and pulp impurities from invading the bearing interior.

 

▸ Split sealing components - The sealing components also adopt a split structure, and installation does not require threading the shaft, completing assembly synchronously with the bearing.

 

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

Installation time comparison:

 

Traditional integral bearings: Requires disassembling couplings, gears, reducers, frames → moving shaft → inserting bearings → re-centering → re-assembly. The typical time is several days to several weeks.

 

NMT split bearings: Opens the bearing housing → removes the old half-ring → installs the new half-ring → secures the bolts. The typical time is only several minutes to several hours.

 

The installation time of split bearings is approximately 15% of that of integral bearings. For example, replacing a 300-ton blast furnace ear shaft bearing, using the split bearing solution, the bearing replacement is completed in only 6 days - while the traditional solution requires several weeks. Split bearings can reduce installation downtime by up to 90%.

 

Maintenance convenience:

 

Can be inspected at any time - No need to disassemble to open the bearing housing to check the operating status of the bearing

 

Split transportation - The bearing can be split into smaller components, simplifying lifting and handling tasks, especially suitable for narrow and difficult-to-reach spaces

 

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

 

VI. Quality Control - Dual Assurance of Split Precision and Overall Strength

NMT implements a strict quality control system for split bearings:

 

Precision processing of split surfaces - Uses high-precision wire-cutting technology to process the split surfaces of the inner and outer rings to ensure the concentricity and strength after the split surfaces are combined

 

High-strength locking system - High-strength steel locking rings and multi-bolt design ensure the stability of the split surfaces during operation without loosening

 

Stepwise joint of split interface - Special stepped interface design enhances the joint strength of the split surfaces, avoiding misalignment during operation Post-assembly precision inspection - After each set of split bearings is assembled, the radial clearance, rotational accuracy, and vibration values are inspected to ensure consistency with the performance of the integral bearings.

 

Seven, Inventory Reserve + Non-standard Customization - Quick response to urgent demands for large-scale equipment

Common split bearing models (split cylindrical roller bearings, split self-aligning roller bearings) are kept in stock - covering 80% of the split bearing demands in industries such as steel, mining, cement, and papermaking. Quick response to emergency failures, minimizing unplanned downtime to the greatest extent.

 

Customizable projects - Special inner and outer diameters/widths (standard range 55mm to 630mm, expandable), special split structure, customized sealing solutions, special materials (stainless steel/heat-resistant steel), special clearance.

 

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

 

Eight, Full Lifecycle Cost Optimization - One shutdown, save millions

Unplanned downtime of large heavy equipment often costs tens of millions. Take the replacement of 300-ton hearbolt bearing for a 300-ton converter as an example: The total cost of the traditional integral bearing solution is as high as 28.2 million yuan (bearing 900,000 + labor installation 300,000 + downtime loss 27 million); while with the split bearing solution, the total cost drops to 18.3 million yuan (bearing 1.9 million + labor installation 200,000 + downtime loss 16.2 million), saving nearly 10 million yuan each time.

 

Hidden costs of low-priced integral bearings:

 

One replacement requires downtime of several days to several weeks, and the downtime loss is dozens to hundreds of times the price of the bearing

 

Axle neck damage during disassembly, repair costs are high

 

After the dynamic balance is disrupted, the equipment vibration intensifies, accelerating the wear of other components

 

When the installation space is narrow, the construction difficulty is extremely high, and the labor cost surges

 

NMT split bearings achieve "one replacement, years of worry-free" in large equipment such as hearbolt shafts of converters, ball mills, rotary kilns, and paper drying cylinders:

 

Downtime is reduced by 80-90% - from daily level to hourly level, the annual unplanned downtime loss is significantly reduced

 

No need to disassemble the shaft for installation to avoid axle neck damage - no need to dismantle the main shaft, avoiding磕碰磨损 during disassembly process from the root

 

Maintain dynamic balance accuracy - without damaging the original assembly structure and dynamic balance state of the equipment

 

Can be inspected and maintained at any time - no need to disassemble the machine to check the bearing condition， preventive maintenance becomes possible

 

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

 

For steel enterprises， mining companies， cement plants， paper mills， power enterprises， and ship operators， the comprehensive holding cost of NMT split bearings is much lower than the repeated disassembly cost of traditional integral bearings - what is saved is not the bearing price difference， but the huge operational risk of "changing the bearing once， shutting down one production line" for large equipment.