638 — 8 × 28 × 9 mm

What each manufacturer published.

A dash means that manufacturer did not publish the value. Dimensions every source agrees on are shown above rather than repeated per row.

Where the sources agree.

Where the figures differ, use the drawing from the manufacturer you buy from.

Calculated from the published values.

Arithmetic on the figures above — not a bearing life calculation for your load case.

The works that publish 638.

CZ

Ningbo, Zhejiang, China

Miniature motor bearings and inch series

Cixi Lisheng manufactures miniature and small motor bearings under the CZ brand. Its catalogue includes metric 60, 62, 68, 69 and 16000 series, inch R series, stainless steel and nonstandard products. The company identifies brushless motors, power tools, garden tools and drones as applications. Confirm the exact model and operating requirements before specifying.

Published ranges: Metric miniature motor bearings · Inch R-series bearings · Stainless steel bearings · Nonstandard bearing designs

72 designations documented here · 1 reviewed evidence record · source recorded 2026-09-24

Ask CZ about 638

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SFH

Shanghai, China

Miniature and thin-section ball bearings

Shanghai Hengan manufactures miniature bearings under the SFH brand, with a factory in Wuxi and technical and inspection functions in Shanghai. Its catalogue covers metric, inch and flanged deep groove bearings, thin-section designs, double-row angular contact bearings and thrust bearings. Special nonstandard designs are also listed.

Published ranges: Metric and inch miniature deep groove bearings · Flanged miniature bearings · Thin-section ball bearings · Double-row angular contact and thrust bearings

51 designations documented here · 1 reviewed evidence record · source recorded 2026-09-24

Ask SFH about 638

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Sihai

Ningbo, Zhejiang, China

Deep groove bearings for motors and automotive use

Cixi Sihai develops and manufactures deep groove ball bearings. Its published scope gives a bore range of 6–35 mm and lists 6000, 6200, 6300, 6800 and 6900 series. Applications include vehicles, appliances, power tools, instruments and office equipment. Automotive engine-related references should be matched to the exact assembly.

Published ranges: 6000, 6200 and 6300 series · 6800 and 6900 series · Automotive engine-bearing applications

85 designations documented here · 1 reviewed evidence record · source recorded 2026-09-24

Ask Sihai about 638

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Yuyao Global

Ningbo, Zhejiang, China

Miniature and small bearings

Yuyao Global manufactures miniature and small bearings. Its published product organization includes rubber-sealed and metal-shielded designs, with applications in appliances, automotive systems, communications equipment and medical devices. The company describes manufacturing and inspection operations in Yuyao; closure type and lubrication should be agreed for the operating environment.

Published ranges: Miniature and small bearings · Rubber-sealed bearing designs · Metal-shielded bearing designs

71 designations documented here · 1 reviewed evidence record · source recorded 2026-09-24

Ask Yuyao Global about 638

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Yuyao Xinfeng

Ningbo, Zhejiang, China

Small ball bearings and custom assemblies

Yuyao Xinfeng manufactures miniature and small bearings in metric and inch dimensions. Its published range includes single- and double-row deep groove bearings, steering-system bearings, full-complement ball bearings, bicycle bearings and thin-ring designs. Nonstandard plastic-bearing combinations are also described. Buyers should identify the complete assembly configuration and mating parts.

Published ranges: Single- and double-row deep groove ball bearings · Metric and inch miniature bearings · Steering and bicycle-bearing designs · Thin-ring and nonstandard assemblies

36 designations documented here · 1 reviewed evidence record · source recorded 2026-09-24

Ask Yuyao Xinfeng about 638

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Applications the publishing works state.

Application areas each manufacturer states for its own range. Confirm load, speed, temperature and lubrication for your case.

Not documented by any source here.

Precision class · Internal clearance · Sealing · Material · Cage material · Z class · V class · Limiting speed · Lubrication · Operating temperature · Precision standard · Ring material · Rolling element material · Limiting speed — grease · Limiting speed — oil · Noise / vibration test method · Manufacturer series · Manufacturer suffix · Reference mass.

Ask the manufacturer for these when you enquire.

Other designations with the same 8x28x9 mm envelope.

Same envelope, but sealing, internal design, clearance and load capability differ — not interchangeable by default.

Neighbouring designations documented here.

Each envelope shown is that designation’s own published size.