Attribute Schema Library
Attribute schemapower transmission & bearings

Ball Bearing Attributes & Specifications

A ball bearing carries radial and axial load on hardened balls running between two rings. The category spans deep groove, angular contact, self-aligning and thrust ball bearings, plus inch-series miniatures. Buyers are MRO planners matching a number stamped on a failed ring, OEM engineers sizing to an L10 life target, and motor rebuilders who care about noise before anything else.

The data is hard because nearly every spec that matters is encoded in the designation suffix, and every manufacturer spells it differently. SKF 6205-2RS1/C3, NSK 6205DDU C3, NTN 6205LLU/C3 and FAG 6205-2RSR-C3 describe near-identical bearings. Price files ship that suffix as an opaque part of the SKU string. The load ratings, speeds, mass and temperature limits live in catalog PDFs organized by dimension series, not by SKU.

Then the variants multiply. One base number crossed with seal, clearance, cage, precision, noise class and grease fill yields dozens of orderable SKUs that differ by three characters and look identical in a list view.

Core

Every SKU needs these. Without them the record is not a product, it is a row.

Bearing Type
enum
Deep groove ball bearing, single row

Sets the whole spec sheet. Deep groove takes combined load, angular contact takes one-direction thrust, self-aligning tolerates shaft misalignment.

Bore Diameter (d)
number · mm
25 mm

The first filter every buyer touches; must match the shaft. Encoded in the base number: the 05 in 6205 is 05 x 5 = 25 mm.

Outside Diameter (D)
number · mm
52 mm

Must match the housing bore. One shaft size spans dimension series: 6205 is 52 mm OD, 6305 on the same 25 mm bore is 62 mm.

Width (B)
number · mm
15 mm

Third of the three ISO 15 boundary dimensions. Sets axial space in the housing and separates otherwise identical series.

Bearing Number (ISO base number)
identifier
6205

The cross-maker key. Strip the suffixes and 6205 is 6205 at every manufacturer. This is the field that makes interchange search work.

Manufacturer Part Number (MPN)
identifier
6205-2RS1/C3

The orderable string, suffixes included. 6205 and 6205-2RS1/C3 are different SKUs at different prices off the same base number.

Seal / Shield Type
enum
Contact seal, both sides (2RS1)

Decides contamination protection, drag and max speed. Open, shielded and contact-sealed builds of one bearing behave nothing alike.

Differentiating

What buyers actually compare on. This is where catalogs win or lose the filter.

Basic Dynamic Load Rating (C)
number · kN
14.8 kN

Per ISO 281, the load giving 1 million revolutions at 90% reliability. The input to every L10 rating life calculation an engineer runs.

Basic Static Load Rating (C0)
number · kN
7.8 kN

Per ISO 76, the load causing permanent deformation of 0.0001 x ball diameter. Governs stationary, oscillating and shock-loaded duty.

Radial Internal Clearance
enum
C3

Wrong clearance kills the bearing. C3 for press fits, thermal growth and motors; CN for general duty; C2 where running accuracy matters.

Limiting Speed
number · rpm
9,000 rpm

Mechanical ceiling set by cage strength, seal rubbing speed and lubricant. Contact seals cut it sharply versus the same bearing shielded.

Cage Type / Material
enum
Glass-fibre reinforced PA66 (TN9)

Pressed steel is the default. Glass-filled PA66 runs quieter but caps near 120 C. Machined brass takes heat and high speed.

Ring & Ball Material
enum
AISI 52100 chrome steel

52100 chrome steel is standard. 440C stainless for washdown and corrosive duty, at a lower load rating. Filtered hard on food and marine jobs.

Operating Temperature Range
range · °C
-30 °C to +110 °C

Set by the seal compound and grease, not the steel. NBR seals tap out around 100-110 C; FKM goes higher at a price.

Compliance & identifiers

Standards, regulatory data, and the identifiers channels reject you for missing.

Precision Class (ISO 492 / ABEC)
enum
ISO 492 Normal (ABEC 1)

Dimensional and running-accuracy tolerance only. Required on spindle, instrument and aerospace RFQs; over-specified nearly everywhere else.

GTIN / UPC
identifier
GTIN-13 (13 digits, no dashes)

Required to list on Amazon Business and to match on marketplaces. A missing GTIN blocks the listing no matter how good the spec block is.

Country of Origin
enum
Germany

Drives duty, Buy American and TAA eligibility on government and defence RFQs, and customer preference. Varies by plant and lot, not by brand.

HTS Code
identifier
8482.10.50 (ball bearings, other)

Ball bearings classify under HTS heading 8482.10; the 10-digit line drives the duty rate. Needed for import, landed cost and cross-border sale.

The fields that aren't in the schema at all

What most ball bearings catalogs are missing.

The table above is the schema most catalogs already have. These are the attributes that usually aren't in it — each one surfaced by a signal from the live market rather than by an audit of what's already there. This is what Anglera's Schema Foundry does on a real catalog, in this category.

Search signal
+ Cross-reference / interchange designations

Buyers type a competitor suffix — 6205DDU, 6205LLU, 6205-2RSR — into distributor site search and get zero results. The catalog only carries the one maker's designation it happens to stock.

Buyer concludes there is no stock and calls a competitor. Every interchange lookup becomes a manual counter call instead of a self-serve order.

Supplier signal
+ Grease type and fill percentage

Manufacturer datasheets state the thickener and the fill as a share of free space (lithium soap mineral oil, 25-35%). Distributor records compress it to 'lubricated' or drop it entirely.

Food-grade, low-temperature and vacuum jobs cannot be filtered at all. Wrong grease into a 120 C application comes back as a warranty claim, not a return.

Competitor signal
+ Noise / vibration class (Z#V# / EMQ)

Specialist bearing suppliers expose EMQ and Z4V4 ratings on their own product pages. General PT catalogs carry no such field, so 'quiet bearing for a motor rebuild' is unanswerable.

Motor rebuild and HVAC blower RFQs go elsewhere. EMQ stock sells at plain-bearing prices because nothing in the record says it is EMQ.

Supplier signal
+ Fatigue load limit (Pu)

SKF and Schaeffler product tables publish Pu next to C and C0. Distributor records copy C and C0 across and silently drop Pu.

Engineers running ISO 281 modified rating life leave for the maker's catalog to finish the calculation, and frequently order there too.

Marketplace signal
+ Snap ring groove / filling slot variant

The N and NR suffixes (snap ring groove, without and with ring, groove per ISO 464) sit inside the part number string but in no filterable field. On marketplaces 6205 and 6205-NR collide.

6205 and 6205-NR look identical in a list view. The wrong one ships, will not seat in the housing, and comes back as a return.

How Schema Foundry finds these

Messy in, governed out.

The same value, spelled every way power transmission & bearings suppliers spell it. A filter only works once they agree.

Seal / Shield Type
2RS1DDULLU2RSR2RSDouble Sealed
Contact seal, both sides

One seal, five maker spellings. A rail filtered on '2RS' hides every NSK and NTN equivalent sitting in the same bin.

Radial Internal Clearance
C3/C3C 3C3 ClearanceGreater than normalLoose
C3

Six strings, one grade. And CM is NSK motor clearance, not C3 — the near-miss a fuzzy match gets wrong.

Bore Diameter
25mm25 mm25.00.9843"0.9843 ind=25
25 mm

Inch-series R-bearings are not rounded metric: R8 is a 0.5 in bore, not 12 mm. Round the conversion and it matches neither rail.

Precision Class
ABEC-1ABEC 1P0Class 0NormalISO Normal
ISO 492 Normal (ABEC 1)

ABEC (ABMA Std 20) and ISO 492 are parallel scales for the same tolerance. Suppliers send either; buyers filter on one.

What buyers ask

Every one of these should be answerable from the attributes above. If it isn't, that's a gap.

  • Is 6205DDU the same bearing as 6205-2RS1? Will it drop into the same housing?
  • Do I actually need C3, or is CN fine for this motor?
  • Will these seals survive 110 C, or do I need it shielded instead?
  • What's the max rpm with contact seals — not the open number?
  • Is this chrome steel or 440C stainless? It's going on a washdown line.
  • What's the dynamic load rating? I need L10 life at 1,200 rpm.
  • Is this one EMQ / low-noise, or standard?
  • Does it have the snap ring groove? My housing has no shoulder.

What channels require

The same SKU, different mandatory fields per destination.

Distributor's own faceted catalog and site search
Bearing TypeBore Diameter (d)Outside Diameter (D)Width (B)Seal / Shield TypeRadial Internal Clearance
Amazon Business
GTIN / UPCManufacturer Part Number (MPN)BrandCountry of OriginBore Diameter (d)Outside Diameter (D)
Grainger / MSC / Fastenal supplier item setup
Manufacturer Part Number (MPN)GTIN / UPCCountry of OriginHTS CodeBore / OD / WidthNet Weight
Customer punchout catalog (cXML / CIF) into ERP
Manufacturer Part Number (MPN)Customer Part NumberUNSPSCUnit of MeasureShort DescriptionBearing Number (ISO base number)

Ball Bearings data, in practice

Does ABEC rating tell me anything about load capacity or speed?

No. ABEC (ABMA Std 20) and ISO 492 govern dimensional and running-accuracy tolerances only — bore and OD deviation, radial runout, width variation. They say nothing about load rating, internal clearance, material, cage design or noise. An ABEC-7 bearing is not 'better' for a conveyor idler; it is tighter. Load capacity comes from C and C0 (ISO 281 / ISO 76). Speed comes from the limiting or reference speed. Quietness comes from the noise/vibration class. Store them as separate attributes — collapsing them into one 'quality' field is why buyers over-spec precision and pay for tolerance they never use.

Should limiting speed and reference speed be one field or two?

Two. Reference speed (ISO 15312) is thermal: the speed at which the bearing reaches thermal equilibrium under standardized load, temperature and cooling. Limiting speed is a mechanical ceiling set by cage strength, seal rubbing speed and lubricant. They are not interchangeable, and manufacturers publish both. For contact-sealed bearings, makers typically publish no reference speed at all, because the seal's rubbing speed sets the limit — so that field is legitimately empty rather than missing. A schema with one merged 'Max Speed' column forces a wrong choice and loses which basis was used.

Where does the spec data for this category actually live?

In the designation string and in PDFs. The base number (6205) encodes type, dimension series and bore. The suffixes carry seal type, cage, clearance and precision — but each maker spells them differently, and price files ship the suffix as an unparsed part of the SKU. C, C0, Pu, limiting speed, mass and temperature range live in the maker's catalog tables, usually a PDF page per dimension series, not keyed by SKU. A record built from the price file alone has a part number, a price, and almost nothing to filter on. Populating the rail means parsing the designation and mining the catalog tables.

How should inch-series bearings be handled alongside metric?

Store the native dimension and unit, plus a normalized value for filtering. Do not convert one into the other and discard the original. R-series inch bearings have bores that do not land on metric sizes: R8 is a 0.5 in bore — 12.7 mm, near but not equal to 12 mm. A rounded conversion turns that into '13 mm' and it matches neither rail. Keep Bore Diameter (mm) and Bore Diameter (in) as parallel values derived from one governed source, and keep the series designation visible so the buyer can see which system the part was designed to.

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