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Oct . 14, 2025 10:00 Back to list

20x52x15mm 21304 CA W33 Spherical Roller Bearing High Load


Hands-on Review: 20x52x15mm 21304 CA W33 Spherical Roller Bearing

If you work with compact drives, conveyors, or vibrating screens, you’ve probably chased the same grail as the rest of us: high load, small footprint, and reasonable price that doesn’t crater your maintenance budget. This little unit—let’s just call it “the 21304” for short—ticks a lot of those boxes. Originating from No. 3, Area B, Bearing Industry Mass Entrepreneurship Park, Beihuan Road, Linxi County, Xingtai City, Hebei Province, it comes from an ecosystem that, frankly, lives and breathes bearings.

20x52x15mm 21304 CA W33 Spherical Roller Bearing High Load

Where it fits in the market

Industry trends are clear: compact spherical roller bearings are filling the gap between deep-groove ball bearings (too fragile in shock load) and larger SRBs (overkill on size and cost). There’s also a push for better lubrication management—hence the W33 groove/holes—and brass cages for heat and stability. To be honest, the demand coming from aggregate handling and agricultural machinery is especially strong right now.

Specs that matter

Parameter Value (≈, real-world may vary)
Designation20x52x15mm 21304 CA W33 Spherical Roller Bearing
Bore × OD × Width20 × 52 × 15 mm
CageCA = machined brass, guided by inner ring
W33Lubrication groove + holes in outer ring
Dynamic/Static ratingCr ≈ 40–45 kN; Cor ≈ 38–42 kN
Limiting speedGrease ≈ 7,000 rpm; Oil ≈ 9,000 rpm
Misalignmentup to ±1.5° typical
MaterialGCr15 / 100Cr6 (AISI 52100), 58–64 HRC
Tolerance/ClearanceISO 492 Normal; C3/C4 optional
Operating temp-30 to +200 °C (with proper lube)
20x52x15mm 21304 CA W33 Spherical Roller Bearing High Load

Process flow and testing

Steel sourcing → forging/turning → heat treatment (controlled atmosphere) → superfinishing of raceways → roller sorting → cage machining (brass) → assembly → vibration test (ISO 15242) → dimensional and runout checks (ISO 492). Static/dynamic ratings align with ISO 76/281. Typical vibration grade meets Z2/V2; runout on small rings is tight—around single-digit microns in my samples.

Service life? With a steady 3.5 kN radial load and clean lubrication, the L10 life model points to tens of thousands of hours. Actually, contamination is the real villain—W33 grease refresh points help.

Applications and real feedback

  • Mining/aggregates: compact screens, conveyors, feeders.
  • Agriculture: threshers, chaff cutters, grain elevators.
  • Wood & recycling: chippers, shredders (shock loads, dust).
  • Industrial fans and compact gearboxes needing misalignment tolerance.

Many customers say it “just runs cooler” than generic imports. One quarry in Hebei swapped to 20x52x15mm 21304 CA W33 Spherical Roller Bearing on a transfer conveyor and reported roughly 23% longer intervals between relubes—small sample size, yes, but promising.

20x52x15mm 21304 CA W33 Spherical Roller Bearing High Load

Customization and compliance

Options: C3/C4 clearance, anti-corrosion coatings, matched sets, and special greases for high temp or washdown. Certifications typically include ISO 9001; IATF 16949 applies to selected automotive-facing lines. Traceability and batch test reports can be issued on request.

Vendor comparison (quick take)

Criteria BTZ (Hebei) Global Tier Low-Cost Import
PriceMidHighLow
Quality ConsistencyStable, auditedExcellentVariable
Lead TimeShort-to-midMidUncertain
Docs/CertsFull pack on requestFullMinimal
20x52x15mm 21304 CA W33 Spherical Roller Bearing High Load

Why pick it

The CA brass cage is rugged, the W33 makes relubing sane, and the small 20 mm bore opens a lot of compact design doors. If you’re upgrading from a deep-groove setup that keeps failing on shock, this is an easy win.

Authoritative citations

  1. ISO 492: Rolling bearings — Radial bearings — Geometrical product specifications and tolerances.
  2. ISO 281: Rolling bearings — Dynamic load ratings and rating life.
  3. ISO 76: Rolling bearings — Static load ratings.
  4. ISO 15242-1: Measurement of vibration of rolling bearings — Part 1.
  5. ISO 15243: Rolling bearings — Damage and failures — Terms, characteristics and causes.
  6. ASTM A295/A295M: High-Carbon Anti-Friction Bearing Steel (AISI 52100).
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