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| Parameter | FAG638-2Z>N8 × 28 × 9 mm | NSK6388 × 28 × 9 mm | KOYO6388 × 28 × 9 mm | EZO6388 × 28 × 9 mm |
|---|---|---|---|---|
| Comparable specifications | ||||
| Brand | FAG | NSK | KOYO | EZO |
| Designation | 638-2Z>N | 638 | 638 | 638 |
| Product family | — | Single row deep groove ball bearings | Extra-small, miniature ball bearings / Standard type / Open | Miniature Ball Bearing |
| Detailed type | Deep groove ball bearings | Deep groove ball bearings | Deep groove ball bearings | Deep groove ball bearings |
| Series | 638 | — | — | — |
| Bore diameterd | 8 mm | 8 mm | 8 mm | 8 mm |
| Outside diameterD | 28 mm | 28 mm | 28 mm | 28 mm |
| WidthB | 9 mm | 9 mm | 9 mm | 9 mm |
| Basic dynamic load ratingC | 4.85 kN | 5.05 kN | 5.65 kN | 4.58 kN |
| Basic static load ratingC0 | 1.97 kN | 1.97 kN | 1.95 kN | 1.97 kN |
| Fatigue load limitPu | 0.122 kN | — | 0.1 kN | — |
| Reference speednref | 24600 r/min | — | — | — |
| Limiting speednG | 34500 r/min | — | 26000 r/min | — |
| Mass≈m | 0.0303 kg | 0.0283 kg | 0.029 kg | 0.0272 kg |
| Precision class | PN — Normal (ISO 492:2023) | — | — | — |
| Internal clearance | CN (Group N) — Normal internal clearance | — | — | — |
| Sealing | 2Z — Non-contact shield on both sides | Open | Open | Open (no closure suffix in this catalogue marking) |
| Cage | JN — Steel sheet metal | — | — | — |
| Bearing material | — | — | — | High-carbon chromium bearing steel |
| Lubricant | Lubricating grease | — | — | — |
| Minimum operating temperatureTmin | -30 °C | — | — | — |
| Maximum operating temperatureTmax | 120 °C | — | — | — |
| Boundary dimensions | ||||
| Bearing width (open)B | — | 9 mm | — | — |
| Outer diameterD | — | — | — | 28 mm |
| Minimum bearing chamferr min. | — | 0.3 mm | — | — |
| Outer diameterD | — | — | — | 1.1024 inch |
| Inner ring widthB | — | — | — | 9 mm |
| Inner ring widthB | — | — | — | 0.3543 inch |
| Outer ring widthC | — | — | — | 9 mm |
| Outer ring widthC | — | — | — | 0.3543 inch |
| Inner ring chamfer dimensionr si min | — | — | — | 0.3 mm |
| Inner ring chamfer dimensionr si min | — | — | — | 0.0118 inch |
| Outer ring chamfer dimensionr se min | — | — | — | 0.3 mm |
| Outer ring chamfer dimensionr se min | — | — | — | 0.0118 inch |
| Calculation factors | ||||
| Calculation factorf0 | 12.4 | — | — | — |
| Capabilities & suitability | ||||
| Radial load capacity | Yes | — | — | — |
| Axial load capacity in one direction | Yes | — | — | — |
| Axial load capacity in both directions | Yes | — | — | — |
| Lifetimelubricationfreedomfrommaintenance | Yes | — | — | — |
| Suitable for grease lubrication | Yes | — | — | — |
| Sealedonbothsides | Yes | — | — | — |
| Classification | ||||
| Official Category Path | — | — | Deep groove ball bearings - Extra-small, miniature ball bearings - Standard type - Open | — |
| Official Classification 1 | — | — | Deep groove ball bearings / Extra-small, miniature ball bearings / Standard type / Open | — |
| Construction | ||||
| Catalogue closure construction | — | Open | — | — |
| Closure interpretation | — | — | — | Open (no closure suffix in this catalogue marking) |
| Material interpretation | — | — | — | High-carbon chromium bearing steel |
| Dimensions | ||||
| Minimum chamfer dimensionrmin | 0.3 mm | — | — | — |
| Minimum chamfer dimensionrmin | 0.012 in | — | — | — |
| Shoulder diameter outer ringD1 | 21.5 mm | — | — | — |
| Shoulder diameter outer ringD1 | 0.846 in | — | — | — |
| Caliber diameter outer ringD2 | 22.7 mm | — | — | — |
| Caliber diameter outer ringD2 | 0.894 in | — | — | — |
| Shoulder diameter inner ringd1 | 14.5 mm | — | — | — |
| Shoulder diameter inner ringd1 | 0.571 in | — | — | — |
| Caliber diameter inner ringd2 | 12.7 mm | — | — | — |
| Caliber diameter inner ringd2 | 0.5 in | — | — | — |
| Load ratings | ||||
| Basic dynamic radial load ratingCr | — | 5050 N | — | — |
| Basic static radial load ratingC0r | — | 1970 N | — | — |
| Lubrication-qualified speed | ||||
| Limiting speed with grease | — | 28000 r/min | — | — |
| Limiting speed with oil (open) | — | 34000 r/min | — | — |
| Catalogue limiting speed (grease) | — | — | — | 28000 r/min |
| Catalogue limiting speed (oil) | — | — | — | 33000 r/min |
| Main Dimensions & Performance Data | ||||
| Basic dynamic load rating, radialCr | 4,850 N | — | — | — |
| Basic dynamic load rating, radialCr | 1,090.378 lbf | — | — | — |
| Basic static load rating, radialC0r | 1,970 N | — | — | — |
| Basic static load rating, radialC0r | 442.896 lbf | — | — | — |
| Fatigue load limit, radialCur | 122 N | — | — | — |
| Fatigue load limit, radialCur | 27.428 lbf | — | — | — |
| Manufacturer Identity | ||||
| Schaeffler Product Code | 2496350 | — | — | — |
| Official Class Key | — | — | 010-020-010 | — |
| Base Type | 638 | — | — | — |
| Gpsd Group | S02 | — | — | — |
| Product Line Id | 14 | — | — | — |
| SAP material number | 3008627920000 | — | — | — |
| Base product | 2305080101 | — | — | — |
| Mounting dimensions | ||||
| Minimum shaft shoulder diameter (open)da min. | — | 10 mm | — | — |
| Maximum adjacent fillet radiusra max. | — | 0.3 mm | — | — |
| Maximum housing shoulder diameter (open)Da max. | — | 26 mm | — | — |
| Adjacent mounting dimension (da min)da min | — | — | — | 22.5 mm |
| Adjacent mounting dimension (da min)da min | — | — | — | 0.8858 inch |
| Adjacent mounting dimension (da max)da max | — | — | — | 26 mm |
| Adjacent mounting dimension (da max)da max | — | — | — | 1.0236 inch |
| Adjacent mounting dimension (r asi max)r asi max | — | — | — | 0.3 mm |
| Adjacent mounting dimension (r asi max)r asi max | — | — | — | 0.0118 inch |
| Adjacent mounting dimension (r ase max)r ase max | — | — | — | 0.3 mm |
| Adjacent mounting dimension (r ase max)r ase max | — | — | — | 0.0118 inch |
| Minimum diameter shaft shoulderda min | 10 mm | — | — | — |
| Minimum diameter shaft shoulderda min | 0.394 in | — | — | — |
| Maximum diameter of housing shoulderDa max | 26 mm | — | — | — |
| Maximum diameter of housing shoulderDa max | 1.024 in | — | — | — |
| Maximum fillet radiusra max | 0.3 mm | — | — | — |
| Maximum fillet radiusra max | 0.012 in | — | — | — |
| Product characteristics | ||||
| Version code>N | Not marked on bearing | — | — | — |
| Type of Seal2Z | Non-contact shield on both sides | — | — | — |
| Tolerance classPN | Normal (ISO 492:2023) | — | — | — |
| Dimensional / heat stabilizationSN | Rings dimensional stabilized up to 120° | — | — | — |
| Radial internal clearanceCN (Group N) | Normal internal clearance | — | — | — |
| Bore typeZ | Cylindrical | — | — | — |
| Product Identity | ||||
| Construction | Deep groove ball bearing 63..-2Z, single row, shields, steel sheet metal cage | — | — | — |
| Short Description | Deep groove ball bearing | — | — | — |
| Reference mass | ||||
| Approximate catalogue mass (open) | — | 28.3 g | — | — |
| Reference mass | — | — | — | 27.2 g |
| Rolling elements | ||||
| Ball diameterDw | — | — | — | 4.762 mm |
| Ball quantityZ | — | — | — | 7 |
| Technical Data | ||||
| d | — | — | 28 mm | — |
| B | — | — | 9 mm | — |
| Bore Diameter (D) | 8 mm | — | — | — |
| R(Min.) | — | — | 0.3 mm | — |
| Outside Diameter (D) | 28 mm | — | — | — |
| Basic Load Ratings : Cr | — | — | 5.65 kN | — |
| Width (B) | 9 mm | — | — | — |
| Basic Load Ratings : C0R | — | — | 1.95 kN | — |
| Basic Dynamic Load Rating, Radial (Cr) | 4,850 N | — | — | — |
| Fatigue Load Limit : Cu | — | — | 0.100 kN | — |
| Basic Static Load Rating, Radial (C0R) | 1,970 N | — | — | — |
| Factor : F0 | — | — | 12.3 | — |
| Operating Temperature Min. (Tmin) | -30 °C | — | — | — |
| Limiting Speeds(Grease Lub.) | — | — | 26000 min-1 | — |
| Limiting Speed (Ng) | 34,500 1/min | — | — | — |
| Limiting Speeds(Oil Lub.) | — | — | 32000 min-1 | — |
| Operating Temperature Max. (Tmax) | 120 °C | — | — | — |
| Da(Min.) | — | — | 10 mm | — |
| Reference Speed (Nϑr) | 24,600 1/min | — | — | — |
| Da(Max.) | — | — | 26 mm | — |
| Calculation Factor (F0) | 12.4 | — | — | — |
| Ra(Max.) | — | — | 0.3 mm | — |
| Fatigue Load Limit, Radial (Cur) | 122 N | — | — | — |
| Mass(Refer.) | — | — | 29 g | — |
| Minimum Diameter Shaft Shoulder (Da Min) | 10 mm | — | — | — |
| Shoulder Diameter Inner Ring (D1) | 14.5 mm | — | — | — |
| Maximum Diameter Of Housing Shoulder (Da Max) | 26 mm | — | — | — |
| Minimum Chamfer Dimension (Rmin) | 0.3 mm | — | — | — |
| Caliber Diameter Inner Ring (D1) | 12.7 mm | — | — | — |
| Maximum Fillet Radius (Ra Max) | 0.3 mm | — | — | — |
| Shoulder Diameter Outer Ring (D1) | 21.5 mm | — | — | — |
| Caliber Diameter Outer Ring (D1) | 22.7 mm | — | — | — |
| Temperature range | ||||
| Operating temperature min.Tmin | -30 °C | — | — | — |
| Operating temperature min.Tmin | -22 °F | — | — | — |
| Operating temperature max.Tmax | 120 °C | — | — | — |
| Operating temperature max.Tmax | 248 °F | — | — | — |
Independent reference comparison based on the manufacturer data currently loaded. Always verify current limits, tolerances and suffix definitions with the official source before engineering selection.