Leave A Message
If you are interested in our products and want to know more details,please leave a message here,we will reply you as soon as we can.
Submit
63 Series
Home Deep Groove Ball Bearings 63 Series

6304 Open Deep Groove Ball Bearing For Internal Machinery & Gearboxes | 20×52×15 mm

6304 Open Deep Groove Ball Bearing For Internal Machinery & Gearboxes | 20×52×15 mm

The 6304 is an unsealed, premium-grade Single-Row Deep Groove Ball Bearing engineered for integration inside secure, enclosed mechanical housings. By entirely omitting side shields and rubber seals, this bearing offers unhindered access to its internal rolling elements, maximizing the flow of external lubricants. With precise metric dimensions of a 20 mm bore, a 52 mm outer diameter, and a 15 mm width, it is categorized under the medium-duty ISO 6300 series. This beefier structural profile provides significantly higher radial and axial load-bearing capabilities than lighter 6000 or 6200 series alternatives of the same bore size.

6304 Deep Groove Ball Bearing 20×52×15 mm | ISO 6300 Series – Medium Duty | Unsealed / Open Architecture

Machined from high-carbon, exact-tolerance SAE 52100 (GCr15) bearing steel, the open architecture of the 6304 eliminates all rotational drag typically caused by closure friction. This frictionless state allows the bearing to safely achieve staggering rotational velocities—peaking at approximately 15,000 r/min when submerged in an industrial oil bath. Because it relies entirely on the machinery’s internal environment for both lubrication and contamination defense, it is the premier choice for sealed transmissions, enclosed internal combustion engines, and precision CNC spindle assemblies where raw mechanical efficiency is paramount.

6304 Open Deep Groove Ball Bearing For Internal Machinery & Gearboxes | 20×52×15 mm

Comprehensive Applications

Designed to operate deep within protected machine casings where oil or grease can circulate freely, the unsealed 6304 is heavily utilized in:

Industrial Transmissions & Speed Reducers
  • Enclosed automotive and industrial gearboxes
  • Oil-bath power transmission mechanisms
  • High-torque planetary gear drives
  • Precision robotic articulating joints
Pumps, Compressors & Fluid Dynamics
  • Internal internal shafts of centrifugal pumps
  • Enclosed rotary screw air compressors
  • Submerged fluid-handling impellers
Electric Motors & Power Generation
  • Fully enclosed fan-cooled (TEFC) motor internals
  • High-efficiency industrial generators
  • Internal auxiliary turbine components
Factory Automation & Tooling
  • High-speed CNC machine tool spindles
  • Automated textile spinning frames
  • Heavy-duty internal printing press rollers

Key Performance Features

01. Zero Rotational Drag

Without any physical seals or metal shields rubbing against the inner ring, the 6304 operates with the absolute minimum amount of friction. This translates to lower power consumption, drastically reduced operational heat, and the ability to sustain maximum RPMs during continuous, multi-shift production cycles.

02. Optimal Lubricant Circulation

The exposed raceways allow continuous, high-volume flushing by the machine’s internal oil or grease supply. This unhindered circulation continuously washes away generated heat and microscopic metal wear particles, preventing overheating and extending the lifecycle of the entire gearbox or motor.

03. Heavy-Wearing 6300 Series Strength

Despite its low-friction profile, the 6304 is highly robust. Featuring larger ball bearings and thicker steel rings than standard-duty variants, it easily absorbs unexpected mechanical shocks and heavy vibrations, boasting a dynamic load capacity of nearly 16.0 kN.

Technical Specifications

Bearing Type Single Row Deep Groove Ball Bearing
ISO Dimension Series 63 Series – Medium Duty
Basic Designation 6304
Suffix Open (No Seals / No Shields)
Bore Diameter (d) 20 mm
Outer Diameter (D) 52 mm
Width (B) 15 mm
Material (Races & Balls) Chrome Steel (GCr15 / SAE 52100)
Precision Class Standard / ABEC-1 / P5 Grade Available
Cage Material Stamped Steel Assembly
Dynamic Load Rating (Cʳ) 15.9 kN
Static Load Rating (C₀ʳ) 7.88 kN
Limiting Speed (Grease) 11,000 – 13,000 r/min
Limiting Speed (Oil) 13,000 – 15,000 r/min
Weight (approx.) 0.144 kg

Interchange Part Numbers

Manufactured to universal metric standards, the unsealed 6304 acts as a direct, precise replacement for global tier-one brands:

  • SKF: 6304
  • NSK: 6304
  • FAG6304
  • NTN: 6304
  • KOYO: 6304
  • Timken: 6304

Design & Configuration

The open 6304 is exclusively intended for "clean" internal installations inside secure machine blocks. It is shipped covered in a specialized rust-preventative oil and must be properly packed with grease or integrated into an oil-lubrication circuit upon installation. While normal internal clearance (C0) is standard and ideal for most assemblies, precision equipment operating at extreme heat or utilizing heavy press-fits onto the shaft will require the C3 increased clearance version. If your application risks exposure to outside dust, grit, or liquids, you must utilize the shielded (6304-ZZ) or sealed (6304-2RS) models to prevent instant bearing failure.

"Combining unhindered high-speed rotation with medium-duty structural strength, the open 6304 maximizes thermal dissipation and fluid lubrication inside heavily enclosed industrial machinery."

Related Products

6302-ZZ Deep Groove Ball Bearing showing Dual Pressed Steel Shields for Dust Protection and Low Friction Torque
6302-ZZ Metric Shielded Ball Bearing | High-Velocity Metal Shield Protection | 15×42×13 mm

The 6302-ZZ stands as a highly versatile, dual-metal-shielded single-row radial ball bearing engineered to deliver exceptional performance under elevated operational speeds and steady radial loads. To minimize drag, this model incorporates twin non-contact pressed steel shields (ZZ) that form a precise barrier over the internal mechanics, retaining factory-applied grease and deflecting dust without creating mechanical friction. Featuring standardized metric dimensions—a 15 mm bore, 42 mm outer diameter, and 13 mm width—the 6302-ZZ provides a highly dependable mechanical solution for power tools, electric motors, and automotive sub-assemblies.

Details
Premium 6303 2RS Replacement Bearing compatible with SKF 6303-2RSH and NSK 6303 DDU for electric motors
6303-2RS Deep Groove Ball Bearing | Premium Double Rubber Seal Protection | 17×47×14 mm

The 6303-2RS represents a highly versatile, single-row radial bearing crafted for exceptional durability and uncompromising contaminant resistance. Outfitted with twin synthetic rubber seals (2RS) that make physical contact with the inner ring, this model securely locks in the factory-applied lubricant while creating a formidable barrier against water, dirt, and industrial grime. Manufactured to standard metric measurements—featuring a 17 mm bore, 47 mm outer diameter, and 14 mm width—the 6303-2RS is an indispensable component for power transmission systems, high-speed power tools, and automotive auxiliaries where reliability is paramount.

Details
Welink 6301-2Z Deep Groove Ball Bearing with 12mm x 37mm x 12mm Dimensions featuring Premium High Stability Grease Fill
6301-ZZ Metric Shielded Ball Bearing | Enhanced Rotational Agility Metal Shield Performance | 12×37×12 mm

The 6301-ZZ stands out as a highly reliable, dual-metal-shielded single-row radial ball bearing engineered to deliver smooth rotational agility under high-frequency conditions and steady radial forces. To minimize power loss, this model incorporates twin non-contact pressed steel shields (ZZ) that form a precise gap over the internal elements, successfully locking in factory-applied grease and deflecting micro-particulates without introducing frictional resistance. Featuring standard metric dimensions—a 12 mm bore, 37 mm outer diameter, and 12 mm width—the 6301-ZZ provides a perfect mechanical solution for compact power tools, small electric motors, and modern appliance hardware.

Details
Heavy Duty 6307-2RZ Bearing constructed from GCr15 Chrome Steel for Industrial Pumps and Centrifugal Blowers
6307-2RZ Non-Contact Sealed Deep Groove Ball Bearing For Pumping Systems | 35×80×21 mm

Engineered as part of the robust 6300 medium-duty series, the 6307-2RZ is a high-performance single-row deep groove ball bearing featuring advanced non-contact rubber seals. With a 35 mm bore, an 80 mm outer diameter, and a substantial 21 mm width, this component is built to handle significant radial and axial loads. The defining feature of the "2RZ" designation is its specialized sealing technology: the rubber lips closely approach the inner ring without making physical contact. This innovative design offers a superior middle ground, delivering far better dust and moisture resistance than standard metal shields (ZZ), while completely avoiding the friction, heat generation, and speed limitations caused by traditional contact seals (2RS).

Details
Welink Bearing premium 636ZZ double shielded deep groove ball bearings ready for industrial installation in precision medical instruments
636-ZZ Miniature Deep Groove Ball Bearing for Precision Mechanics | 6×22×7 mm

Engineered to deliver exceptional rotational accuracy in compact spaces, the 636-ZZ is a premium miniature single row deep groove ball bearing equipped with dual metal shields. Unlike open configurations, the "ZZ" design features pressed steel shields on both sides of the bearing. These non-contact shields act as a robust barrier against the ingress of dust, metallic debris, and environmental particulate matter, while simultaneously retaining the factory-applied lubrication. This makes it an essential, maintenance-free solution for sensitive, high-speed applications like micro-motors, precision instruments, and consumer electronics where reliable, low-noise operation is strictly required.

Details
633-ZZ Miniature Ball Bearing showing Double Pressed Steel Shields for Dust Protection and Low Friction Torque
633-ZZ Miniature Deep Groove Ball Bearing for High-Speed Precision | 3×13×5 mm

Engineered for micro-mechanical applications requiring ultra-fast rotation and low frictional torque, the 633-ZZ is a premium miniature single row deep groove ball bearing equipped with dual metal shields. Unlike heavy-duty or rubber-sealed counterparts, this micro-bearing utilizes non-contact steel shields that offer excellent defense against dry dust and debris while maintaining virtually zero drag. This makes it an essential component for compact, high-velocity mechanics such as 3D printers, robotics, and small electric motors, where preserving kinetic energy and managing tight clearances are top priorities.

Details
6311-ZZ Heavy Duty Deep Groove Ball Bearing 55x120x29mm showing Double Steel Shields for Large Industrial Motors and Gearboxes
6311-ZZ Heavy-Duty Deep Groove Ball Bearing | 55×120×29 mm for Industrial Machinery & Large Motors

Built to endure rigorous operating conditions and heavy mechanical stress, the 6311-ZZ is a premium medium-to-heavy series deep groove ball bearing. Equipped with dual pressed-steel shields (ZZ), it provides an excellent barrier against industrial debris and particulate contamination while securely retaining the factory-applied lubricant. Because the metal shields are non-contacting, this bearing minimizes friction and heat generation, making it the optimal solution for high-load, 55mm shaft applications such as large electric motors, industrial gearboxes, and agricultural equipment.

Details
639-ZZ Deep Groove Ball Bearing featuring Double Steel Shields for Dust Protection and Low Friction
639-ZZ Miniature Deep Groove Ball Bearing | 9×30×10 mm for High-Load Power Tools & Motors

Built for demanding mechanical environments that require high load tolerance in a miniature form factor, the 639-ZZ is a robust deep groove ball bearing from the 630 medium-duty series. Outfitted with dual pressed-steel shields (ZZ), it provides exceptional defense against industrial dust and particulate ingress while securely locking in the factory-applied lubricant. Because these metal shields are non-contacting, the 639-ZZ operates with minimal friction and significantly reduced startup torque, making it an outstanding choice for 9mm shaft applications like power tool armatures, electric motor rotors, and industrial pumps.

Details

Leave A Message

Leave A Message
If you are interested in our products and want to know more details,please leave a message here,we will reply you as soon as we can.
Submit

Home

Products

whatsApp

contact