Sill Bearing
Sill Bearing
Browse our high-performance product lineup manufactured to meet strict international standards and optimize rotational efficiency.
The 6304 ball bearing is one of the most versatile and critical components utilized across mechanical power transmission systems. Classified as a deep groove ball bearing, its geometry features a deep, uninterrupted raceway groove that allows it to carry significant radial loads as well as light-to-moderate axial loads in both directions.
Manufactured primarily from ultra-purified GCr15 bearing steel (the Chinese standard equivalent to AISI 52100 in the USA, DIN 100Cr6 in Europe, and SUJ2 in Japan), the 6304 bearing has a chemical structure specifically optimized for wear resistance, fatigue life, and structural integrity. The steel is heat-treated through a rigorous quenching and tempering process, bringing the rolling elements and inner/outer rings to an operating hardness of 60 to 65 HRC (Rockwell Hardness Scale).
| Dimensional Attribute | Measurement Metric (mm) / Standard Specification | Description & Fit Tolerance |
|---|---|---|
| Bore Diameter (d) | 20 mm | Inner ring fitment on shafts, standard h6 or j6 shaft tolerance |
| Outer Diameter (D) | 52 mm | Outer ring housing fitment, H7 housing tolerance standard |
| Width (B) | 15 mm | Axial space constraints matching standard housings |
| Basic Dynamic Load Rating (Cr) | 15.9 kN | Maximum continuous load for 1 million cycles before fatigue |
| Basic Static Load Rating (Cor) | 7.8 kN | Maximum load capacity before permanent plastic deformation |
| Limiting Speed (Grease) | 11,000 RPM | Optimal rotational speeds with high-grade synthetic grease |
| Limiting Speed (Oil) | 16,000 RPM | Continuous speed when operating under an oil-bath system |
Our production options provide customers with choices suited to distinct operational requirements. SILL bearings are available in open designs, metal-shielded designs (6304 ZZ using pressed carbon steel shields), or synthetic rubber-sealed designs (6304 2RS utilizing Nitrile Butadiene Rubber bonded to structural steel plates). Depending on the working environment, these closures help retain pre-lubricated high-performance grease while blocking micro-particulates, moisture, and chemical contamination.
Analyzing how localized geographic industries rely on the specific dynamics of the 6304 bearing architecture to guarantee smooth uptime and operation.
In the global automotive market, 6304 bearings are deployed inside alternator shafts, electric vehicle cooling pumps, and auxiliary powertrains. The C3 clearances allow for thermal expansion during continuous high-RPM runtimes, ensuring no locking occurs inside the motor casing.
Used heavily in harvester gearboxes, tractor PTO shafts, and sorting machinery. Due to severe exposure to dirt, grain dust, and moisture, our double-sealed (2RS) variants provide tight sealing to prevent premature bearing failure in remote farming environments.
Chemical processing and municipal water pumps rely on the low friction coefficient and minimal vibration properties of our high-grade 6304 bearings. Minimizing friction directly correlates to energy efficiency and lowered operational carbon footprints.
As mechanical engineering marches towards higher speeds, electrification, and intelligent condition monitoring, the technical roadmaps for standard deep groove ball bearings like the 6304 are rapidly evolving. The next generation of industrial applications demands components that are not just passive load carriers, but active contributors to digital machine ecosystems.
1. Material Science and Tribological Innovations: Future development focuses on refining metallurgy to eradicate micro-inclusions in GCr15 steel, significantly extending L10 fatigue life under high load densities. Research into ceramic hybrid ball designs—using Silicon Nitride (Si3N4) balls housed inside steel rings—offers superior insulation properties. This prevents electrical pitting, which is a common failure point inside high-frequency EV inverters and variable frequency drive motors.
2. Smart Bearings & Sensor Integration: The integration of micro-sensors directly within the bearing shield or seal is on the horizon. These integrated units continuously monitor real-time metrics including temperature, speed, structural vibration peaks, and lubrication degradation. This data is wirelessly transmitted directly to plant SCADA systems, enabling predictive maintenance models that stop costly catastrophic failures before they happen.
3. Sustainable Lubricants & High-Temperature Durability: In keeping with global carbon-neutral goals, our research division is optimizing bio-synthetic and ester-based greases that perform over wide temperature ranges (-40°C to +180°C) without losing viscosity. Advanced seal geometries, featuring multi-lip non-contact structures, minimize friction torque by up to 30%, which helps boost system efficiencies.
Versatile, self-retaining bearings with deep groove raceways. Ideal for high speeds, low noise, and minimal maintenance, available in single/double rows, and open/sealed variants.
Separate bearings with tapered raceways on inner/outer rings. Perfect for heavy radial and axial combined loads, available in single, double, or four-row structures.
Engineered to support large one-way axial loads. The structural load capacity scales proportionally with the contact angle of the rolling elements.
Compact combinational design providing high precision and high radial load capacity, saving radial space in heavy industrial machinery.
Sill Bearing Factory is strategically situated in the Hangzhou Bay New Zone, one of China's most advanced manufacturing hubs. This location offers major logistical advantages, positioning our factory near the country's two largest deep-water ports: the Shanghai Port and the Ningbo Port. We are also adjacent to the Hangzhou-Ningbo Expressway, the 329 State Line, and the Hangzhou-Ningbo Railway, allowing fast, convenient container transport. For domestic and international trade, our facility is only about 90 minutes from the Hangzhou Xiaoshan Airport and the Ningbo Lishe Airport.
To support growing global demand, we have expanded our capacity with a new facility: Anhui TOPB Imp. & Exp. Co., Ltd. Once this facility reaches full production, our annual output capacity will increase by $20 million, allowing us to supply large projects on short timelines.
At Sill Bearing Factory, our team takes pride in every product. We train our technicians to handle each bearing with maximum precision and care. To guarantee a 100% product acceptance rate, we use a thorough 5-stage quality check process:
Modern machinery is operating under higher speeds, stricter noise limits, and tougher environmental conditions. The global market is shifting from standard, open bearings toward customized, shielded, and sealed units with specialty greases. Manufacturers and buyers around the world need suppliers who can balance product performance with cost efficiency and reliable logistics.
Under our proprietary brands, SILL and NETB (and through our OEM services), we design products that help lower noise, vibration, and friction while offering long service life. Today, our bearings are used in the US, Brazil, Switzerland, UAE, Iran, Turkey, Pakistan, Malaysia, Bangladesh, Egypt, Nigeria, and other regions.
We work with international distributors, machinery builders, and replacement parts suppliers to provide custom laser marking, customized lubrication, and tailored retail packaging.
Our manufacturing and processing lines strictly adhere to international environmental and safety standards, such as RoHS and REACH, to ensure smooth customs clearance globally.
We provide full technical support, including bearing design advice, failure analysis reports, and installation guides, to ensure optimal performance in the field.
Ultra-thin section bearings for radial space-constrained systems.
Extremely light series bearings offering minimal rolling resistance.
Thick rings designed for high dynamic load capacity and impact resistance.
Highly versatile standard configuration balancing load and speed capability.
Sill Bearing Factory manufactures deep groove ball bearings (ranging from ￠4mm to ￠120mm), tapered roller bearings, and custom non-standard bearings. From our factory in the Hangzhou Bay New Zone, we serve global buyers looking for reliable, high-performance rolling components.
We work to build long-term relationships through transparent quality control and reliable delivery. Contact us today to discuss your technical specifications, request a sample, or get a quotation on our SILL and NETB brand products.
From miniature deep groove ball bearings to specialized heavy industrial bearings, we supply components for a wide range of machinery.
Whether you need high-volume supply for manufacturing or custom OEM solutions, we provide reliable quality and logistics support.
