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63 Series
Home Deep Groove Ball Bearings 63 Series

6304-ZZ Double Shielded Deep Groove Ball Bearing For High-Velocity Industrial Use | 20×52×15 mm

6304-ZZ Double Shielded Deep Groove Ball Bearing For High-Velocity Industrial Use | 20×52×15 mm

The 6304-ZZ is a heavy-wearing, medium-duty Deep Groove Ball Bearing constructed with twin stamped steel closures (ZZ). Engineered to strike the perfect balance between high-speed rotational capability and robust load support, this bearing is an essential component for continuous-running machinery. Measuring 20 mm for the inner bore, 52 mm across the outer diameter, and featuring a 15 mm width, it belongs to the ISO 6300 series. This classification means it features larger internal rolling elements and a thicker raceway cross-section than standard light-duty alternatives, granting it exceptional resilience under substantial radial and moderate axial stresses.

6304-ZZ Deep Groove Ball Bearing 20×52×15 mm | ISO 6300 Series – Medium Duty | Twin Metal Shielded

Forged from premium SAE 52100 (GCr15) exact-tolerance chrome steel, the 6304-ZZ is built to withstand rigorous industrial operational cycles. The defining asset of the "ZZ" designation is its non-contact metallic shields. Unlike rubber seals that grip the inner ring and create drag, these steel shields hover fractions of a millimeter above the inner race. This frictionless defense effectively repels dry particulates, sawdust, and metallic shavings while allowing the bearing to achieve exceptional rotational velocities (up to 13,000 r/min) with minimal thermal expansion. Pre-filled with high-grade industrial grease, it delivers a maintenance-free, drop-in solution for dry and dusty environments.

6304-ZZ Double Shielded Deep Groove Ball Bearing For High-Velocity Industrial Use | 20×52×15 mm

Comprehensive Applications

Thanks to its combination of high RPM limits, dust protection, and medium-duty load ratings, the 6304-ZZ is widely deployed across diverse mechanical sectors:

Electric Motors & Power Generation
  • Industrial electric motor armatures
  • High-RPM industrial cooling fans and blowers
  • Commercial power tool drive shafts
  • Wind turbine auxiliary generators
Material Handling & Manufacturing
  • Heavy-duty conveyor belt drive rollers
  • Automated packaging machinery linkages
  • CNC machine tool auxiliary mechanisms
  • Textile spinning and weaving equipment
Automotive & Mobile Equipment
  • Heavy-duty vehicle alternators and starter mechanisms
  • Transmission support shafts
  • Commercial lawn and turf care equipment wheels
Pumps & Compressors (Dry Zones)
  • Industrial air compressor drives
  • Centrifugal fan housings
  • Fluid processing pumps (external dry components)

Key Performance Features

01. Frictionless Dust Exclusion

The dual steel shields (ZZ) provide a highly effective physical barricade against ambient factory dust and airborne debris. Because the shields do not physically rub against the rotating inner ring, the bearing operates with practically zero friction-induced drag, conserving energy and keeping operational temperatures remarkably low.

02. Medium-Duty Structural Superiority

As part of the 6300 dimension series, the 6304 offers a significantly higher dynamic load capacity (approx. 15.9 kN) compared to 6004 or 6204 standard counterparts. This thicker architecture dramatically reduces the risk of metal fatigue in applications subjected to sudden shocks or heavy continuous loads.

03. Pre-Lubricated for Lifecycle Longevity

Factory-packed with a calculated volume of high-quality, temperature-resistant lithium grease, this bearing requires absolutely no external lubrication or maintenance after installation, sharply decreasing machinery downtime and long-term service costs.

Technical Specifications

Bearing Type Single Row Deep Groove Ball Bearing
ISO Dimension Series 63 Series – Medium Duty
Basic Designation 6304
Suffix ZZ / 2Z (Double Stamped Steel 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 Pressed 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) --
Weight (approx.) 0.144 kg

Interchange Part Numbers

Manufactured to strict international metric sizing standards, the 6304-ZZ ensures seamless interchangeability with leading top-tier brands:

  • SKF: 6304-2Z
  • NSK: 6304ZZ
  • FAG6304-2Z
  • NTN: 6304ZZ
  • KOYO: 6304ZZ
  • Timken: 6304-2Z

Design & Configuration

The 6304-ZZ is precisely tailored for mechanisms operating at high speeds in environments filled with dry contaminants. Most standard stock features a normal internal radial clearance (C0). For specialized machines expected to generate intense internal thermal expansion, or installations utilizing extreme press-fits, bearings configured with C3 internal clearance are readily available. Please note: while the steel shields are exceptional at blocking solid particulate, they are not completely waterproof. If your machinery is regularly exposed to water spray, fluid washdowns, or thick mud, upgrading to the rubber-sealed alternative (6304-2RS) is highly recommended.

"Combining the high-speed efficiency of non-contact shielding with the brute strength of a medium-duty architecture, the 6304-ZZ ensures smooth, uninterrupted power transmission in aggressive industrial environments."

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