1. The “Converter Dilemma“ of Bearing Replacement in the Steel Industry

The steel industry is a classic example of continuous heavy industry. From ore transfer, ironmaking and steelmaking to continuous casting, hot rolling and cold rolling, the entire steel production line operates 24/7, 365 days a year. The working conditions in the steel industry are generally described as hot, wet, dirty, oily, dusty and noisy. Bearings in converter trunnions, continuous casters, rolling mills, conveyors and other critical equipment operate year-round under high-temperature radiation, extreme dust and heavy impact loads.

 

Converter trunnion bearings are among the most difficult to replace and have the highest downtime costs in steelmaking. Taking a 300-ton converter as an example, its trunnion bearing has an outer diameter of 1850mm and weighs over 5 tons. The original design used a solid spherical roller bearing, requiring disassembly of the drive gear and part of the gearbox before replacement could be carried out. However, due to confined installation space and the large number and weight of surrounding components, disassembly and movement were extremely difficult. The entire replacement project was extremely time-consuming, with downtime losses reaching tens of millions of yuan.

 

Typical pain points of traditional solid bearings in the steel industry:

 

Extremely long converter trunnion replacement cycles – Solid spherical roller bearing replacement requires disassembling the drive gear and part of the gearbox first, with the entire project extremely time-consuming. For extra-large bearings with 1850mm outer diameter and over 5 tons, traditional solutions even require weeks of downtime.

 

Difficult rolling mill and continuous caster bearing replacement – In rolling and continuous casting, segment drive roll bearing replacement typically requires removing the entire roll, with large workloads and days to weeks of downtime.

 

Extremely confined working space – Converter trunnions are located in confined spaces on both sides of the furnace body, and continuous caster segments have dense internal structures – lifting equipment can hardly access during maintenance, making disassembly extremely difficult.

 

Extreme conditions accelerate bearing wear – Steel mill environments are hot, wet, dusty and oily. Converter trunnion bearings endure high-temperature radiation and tilting impact, rolling mill bearings endure continuous alternating loads – traditional solid bearings have limited life under harsh conditions.

 

Extremely long spare parts lead times – Lead times for extra-large bearings can be as long as 12 to 18 months – once unplanned downtime occurs, waiting for spare parts further compounds production losses.

 

Downtime causes enormous losses – Steel production lines operate 24/7 – one day of unplanned converter downtime costs millions. Planned solid bearing replacement requires 3 weeks of downtime, with unplanned downtime losses even greater.

 

2. NMT Split Bearings for the Steel Industry: No Gear Removal, No Shaft Removal, Quick Bearing Replacement

NMT split bearings for the steel industry perfectly combine the core advantage of split bearings – “no-shaft-removal installation“ – with the special requirements of steel mill equipment. The inner ring, outer ring, rolling elements and cage are all split along the axial direction – installation requires no removal of shafts, gears, couplings or any other core components – assembly is completed directly on the shaft in situ. Split bearings enable rapid disassembly and replacement without dismantling shaft systems or integrated equipment.

 

More critically – NMT split bearings can be replaced without removing drive gears, without moving shaft systems, without using large lifting equipment. In converter trunnion bearing applications, the split structure enables bearing replacement without removing the drive gear. This is like installing a “service door“ on steel mill equipment, enabling true “online“ maintenance. Compared to traditional solid bearings, split bearings can reduce maintenance time by over 80%.

 

▸ Full Split + Heavy-Duty High-Temperature Construction: Every Piece Can “Go in Separately, Rotate Together“ – Withstanding Steel Mill Conditions

 

Every component of an NMT split bearing for the steel industry is split – split inner ring, split outer ring, split cage with rolling elements, split seals. During installation, these half-ring components are assembled sequentially around the shaft. After being locked with high-strength bolts, they form a precision transmission unit with performance fully equivalent to a solid bearing. Precision step-type mating or V-shaped split joint design at the split interfaces ensures load capacity and rotational precision equal to solid bearings. Split spherical roller bearings as spare parts make it possible to very quickly replace the bearings and thus significantly reduce downtime costs.

 

In terms of materials, NMT offers a complete impact-resistant and heat-resistant steel system for steel industry high-temperature, heavy-load, high-dust applications – carburized bearing steel with deep-case hardening achieves uniform surface hardness HRC60-64 while the core maintains sufficient toughness to absorb impact loads. For high-temperature applications such as converter trunnions, heat-resistant steel and thermal stabilization treatment are available.

 

▸ No-Shaft-Removal Installation: No Gear Removal, No Coupling Removal, No Large Lifting Equipment

 

The core value of NMT split bearings for the steel industry is – bearing replacement without moving the shaft, without removing drive gears and couplings, without using large lifting equipment. In the NSK 300-ton converter case, by adopting split spherical roller bearings, the bearing replacement was completed in just 6 days – greatly reducing the replacement time, improving maintenance efficiency and significantly reducing downtime losses. Schaeffler split spherical roller bearings as spare parts also achieved bearing replacement within the shortest possible time.

 

For continuous caster segment drive roll bearings, NSK split cylindrical roller bearing units enable bearing replacement without removing the roll, eliminating the complexity of dismantling the roll. Maintenance personnel simply open the bearing housing, remove the old bearing halves, install the new bearing halves, and tighten the bolts – complete.

 

▸ Interchangeable with Standard Heavy-Duty Solid Bearings: Seamless Replacement, No Modifications

 

NMT split bearings for the steel industry are designed with full interchangeability with standard heavy-duty solid bearings in mind. Split spherical roller bearings can be installed in split plummer block housings without additional machining. This means steel mills can directly replace existing solid bearings in their equipment with NMT split bearings without any modifications to bearing housings. Converter trunnion bearings using split spherical roller bearings as replacements can be replaced without changing the bearing bore and outer diameter dimensions.

 

3. Full Series Split Bearing Types for the Steel Industry

NMT offers a complete split bearing product system covering multiple steel mill equipment applications:

 

▸ Steel Industry Split Spherical Roller Bearings

 

Split spherical roller bearings are the most widely used split bearing type in the steel industry, capable of withstanding heavy loads and impact loads, adapting to harsh conditions. NMT split spherical roller bearings are specifically designed for converter trunnions, continuous casters, rolling mills and other heavy-load applications – inner rings, outer rings and cages with rollers are all split in half. Spherical outer ring raceways and barrel-shaped rollers provide self-aligning capability, effectively compensating for shaft deflection and installation errors.

 

Converter trunnions are the most typical split spherical roller bearing application in the steel industry. A domestic 300-ton converter trunnion bearing (1850mm outer diameter, over 5 tons) using NSK split spherical roller bearings completed replacement in just 6 days. At ThyssenKrupp‘s steelworks in Italy, FAG Industrial Services successfully replaced large split spherical roller bearings on a 140-ton converter within three days. Each converter vessel weighs 1300 tons. At a US steel mill, three converters installed SKF Cooper split spherical roller bearings in the locating bearing position, achieving total cost of ownership savings.

 

Typical applications of split spherical roller bearings also include continuous caster segments, rolling mill gearbox housings, rolling mill roller tables, crushers and more. Split roller bearings are used at the inner support points of driven rolls. Schaeffler UK received an emergency call from a steel mill when the non-drive side bearing of the V2 BOS plant vessel suffered sudden failure – the team completed the main trunnion bearing replacement using split bearings.

 

▸ Steel Industry Split Cylindrical Roller Bearings

 

Split cylindrical roller bearings use cylindrical rollers to carry high radial loads, with extremely strong radial load capacity, low friction coefficient and low operating temperature rise. Inner and outer rings each split in half, with one or two rows of cylindrical rollers in a split cage.

 

Typical applications of split cylindrical roller bearings include crankshafts of Pilger seamless steel tube mills, bucket wheel excavators, conveyor pulleys, rolling mill drive shafts and large critical ventilation equipment. In the continuous caster field, NSK split cylindrical roller bearing units are specifically designed for segment drive rolls, simplifying bearing replacement without removing the roll. Split cylindrical roller bearing units with self-aligning housings and sleeves can be used on rolling mill roller tables, continuous caster rolls and other locations where bearings are difficult to remove.

 

▸ Steel Industry Split Tapered Roller Bearings

 

NMT split tapered roller bearings feature two rows of opposed tapered rollers, capable of simultaneously bearing radial and bidirectional axial loads, specifically designed for combined loads. SKF Cooper split tapered roller bearings are available in a complete range of specifications, widely used in steel metallurgy, mining and other industries.

 

▸ Split Housed Bearing Units

 

NMT offers split housed bearing units that integrate split bearings and housings as a complete assembly. Paired with high-performance sealing solutions such as SKF Taconite seals, they effectively address the challenges of high contamination and high temperatures in the steel industry. Widely used in steel industry conveyors, fans, bucket wheel machines, continuous casters and other equipment.

 

4. Specialized Sealing and Lubrication Systems – Adapting to High Temperature, High Dust and High Contamination Environments

Steel mill equipment operates year-round under harsh conditions of high temperature, high dust and high contamination. NMT split bearings for the steel industry feature customized sealing and lubrication systems:

 

▸ Heavy-Duty Labyrinth Seal Structure – Non-contact design using centrifugal force from rotation to expel dust, iron scale and contaminants. Maintains reliable sealing in dusty steel mill environments, effectively blocking iron oxide scale, dust and other contaminants while preventing grease leakage.

 

▸ Taconite Seal Upgrade – For high-dust, high-contamination environments (rolling mills, continuous casters), NMT offers heavy-duty sealing solutions such as Taconite seals. SKF Taconite seals are a new global solution for split housings for self-aligning bearing applications in the mining, mineral and metal processing, cement, marine and pulp and paper industries where the ingress of contaminants poses a challenge to bearing service life.

 

▸ Split Seals – Seals are also split for installation without shaft threading, assembled simultaneously with the bearing.

 

5. Installation and Maintenance – An Efficiency Revolution from “Weeks“ to “Days/Hours“

Installation Time Comparison:

 

Traditional steel industry solid bearing: Shutdown → remove drive gear, couplings, gearboxes → move shaft → slide bearing on → realign → reassemble → recommission. Typical time: weeks (planned downtime requires 3 weeks).

 

NMT split bearing: Shutdown → open bearing housing → remove old halves → install new halves → tighten bolts → complete. Typical time: days (300-ton converter just 6 days) to hours.

 

NMT split bearings for the steel industry can reduce bearing replacement downtime by over 80%. Split roller bearing installation can reduce mean time to repair by 65-70%.

 

Specific Case Data:

 

Northern China steel mill 300-ton converter: Trunnion bearing 1850mm outer diameter, over 5 tons. After adopting split spherical roller bearings, replacement was completed in just 6 days, significantly reducing downtime losses.

 

US steel mill three converters: Installed SKF Cooper split spherical roller bearings, achieving total cost of ownership savings exceeding $350,000.

 

ThyssenKrupp steelworks, Italy: FAG successfully replaced large split spherical roller bearings on a 140-ton converter within three days.

 

FAG split spherical roller bearing application: Downtime shortened by 36 hours, saving 40,000 euros (72,000 Australian dollars).

 

Steel mill BOS plant: Sudden bearing failure – the team completed emergency main trunnion bearing replacement using split bearings.

 

Maintenance Convenience:

 

No drive gear removal – For converter trunnion bearing replacement, the drive gear stays in place.

 

No roll removal – For continuous caster segment drive roll bearing replacement, no need to remove the entire roll.

 

No large lifting equipment required – Bearings are handled in sections – easy installation.

 

Inspect anytime – Bearing housing can be opened for inspection without disassembly.

 

No on-site adjustment – Clearances are preset at the factory – no on-site adjustment or specialized tools required.

 

6. Quality Control – Triple Assurance of Split Precision, Heavy-Duty Strength and Seal Reliability

NMT implements a strict quality control system for steel industry split bearings:

 

Heavy-duty heat-resistant material certification – Each batch of bearing steel undergoes impact load testing and high-temperature hardness inspection to ensure performance meets steel mill high-temperature heavy-load requirements.

 

Precision split surface machining – High-precision wire cutting for inner and outer ring split surfaces, ensuring concentricity and strength after assembly.

 

High-strength locking system – High-strength steel clamp rings and multiple bolts ensure split surfaces remain secure during operation.

 

Seal performance verification – Each batch undergoes high-dust environment seal testing to ensure sealing effectiveness under high-contamination steel mill conditions.

 

Post-assembly precision inspection – Each split bearing is inspected for radial clearance, rotational accuracy and vibration after assembly – ensuring performance equivalent to solid bearings.

 

7. Stock Availability + Customization – Rapid Response to Steel Mill Emergency Needs

Common steel industry split bearing models (split spherical roller bearings, split cylindrical roller bearings, split tapered roller bearings) kept in stock – Covering over 80% of split bearing needs for converter trunnions, continuous casters, rolling mills, conveyors and other applications. Emergency failures receive rapid response – minimizing unplanned downtime. Note: Lead times for extra-large bearings can be as long as 12 to 18 months – pre-stocking split bearing spares can dramatically shorten emergency downtime.

 

Custom solutions available – Special bore/OD/width (standard range 55mm to 630mm, expandable to 1850mm+), custom heavy-duty heat-resistant materials (carburized bearing steel/heat-resistant steel), special split configurations, custom sealing solutions (Taconite seals/heavy-duty labyrinth), custom clearance, split housed bearing units.

 

Rapid customization from samples or drawings – Provide old bearing samples or equipment drawings – NMT completes surveying and custom production quickly. Cost-effective replacement for imported brands (SKF Cooper, FAG, NSK, Timken) with significant procurement savings.

 

8. Lifecycle Cost Optimization – No Gear Removal, No Shaft Removal, Save Millions in Downtime Losses

Unplanned downtime in the steel industry often costs tens of millions or even hundreds of millions of yuan. Taking the 300-ton converter trunnion bearing replacement as an example: the traditional solid bearing solution requires weeks of downtime, with enormous production losses; with the split bearing solution, replacement was completed in just 6 days. At a US steel mill, three converters installed SKF Cooper split spherical roller bearings, achieving total cost of ownership savings exceeding $350,000. FAG split spherical roller bearings shortened downtime by 36 hours, saving 40,000 euros.

 

Hidden costs of cheap heavy-duty solid bearings:

 

Converter replacement requires weeks of downtime – downtime losses are hundreds or even thousands of times the bearing price.

 

Extra-large bearing lead times are 12 to 18 months – waiting for spares during unplanned downtime compounds losses.

 

Disassembly of drive gears, couplings and surrounding components is time-consuming and may cause secondary damage.

 

Rolling mill and continuous caster bearing replacement requires removing entire rolls – enormous workload and downtime.

 

Standard heavy-duty bearings have limited life under harsh steel mill conditions – frequent replacement compounds the above losses.

 

Steel mill environments are hot, wet, dusty and oily – accelerating wear and corrosion.

 

NMT split bearings for the steel industry deliver “no gear removal, no shaft removal, quick bearing replacement without production stoppage“ in converter trunnions, continuous casters, rolling mills and conveyors:

 

Downtime reduced by over 80% – From weeks to days/hours – annual unplanned downtime losses dramatically reduced.

 

No drive gear removal – Converter trunnion bearing replacement keeps drive systems in place.

 

No roll removal – Continuous caster bearing replacement without removing entire rolls.

 

Heavy-duty heat-resistant steel withstands high temperatures and harsh environments – Carburized bearing steel and deep hardening resist impact loads and high-temperature radiation.

 

Superior sealing for high-dust environments – Taconite seals and other solutions effectively address steel mill high-contamination challenges.

 

Rapid spare parts response – Split bearings as spares enable replacement within the shortest possible time – avoiding long lead times.

 

Extended life of equipment (gears, gearboxes, couplings) – Fewer disassembly cycles – longer overall equipment overhaul intervals.

 

For steel mills, rolling mills, foundries and various metal processing facility maintenance departments, the total cost of ownership with NMT split bearings for the steel industry is significantly lower than the repeated disassembly and replacement costs of traditional heavy-duty solid bearings – what you save is not bearing price difference, but the enormous operational risk of “replacing one bearing, shutting down an entire production line“ in steel equipment.