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Bearing components and materials

Every rolling bearing is a small assembly of rings, rolling elements, a cage and, often, seals and grease. Some buyers need those parts on their own - to build, rebuild or repair bearings. Start with the part you need, or send a drawing through the quote form.

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Disassembled bearing parts laid out: inner ring, outer ring, steel balls and a cage on a bench
Round bars and tube sections of bearing steel stacked beside finished bearing rings BD-019Bearing steelGCr15, carburizing steel and 440C stainless for rings, balls and rollers, with certificates.View line Forged and turned bearing outer rings and inner rings in stages from blank to ground finish BD-020Bearing ringsInner and outer rings, turned or finished, to P0, P6 or P5 on drawing.View line Bearing cages in pressed steel, brass and glass-fibre nylon beside a deep groove ball bearing BD-021Bearing cagesPressed steel, brass, PA66-GF and phenolic cages in ribbon, crown and window types.View line Polished chrome steel bearing balls in a tray beside stainless and ceramic balls of the same diameter BD-022Bearing ballsChrome steel, stainless and ceramic balls in ISO 3290 grades G3 to G200.View line Cylindrical, tapered, barrel-shaped and needle bearing rollers laid out in rows on a flat surface BD-023Bearing rollersCylindrical, tapered, spherical and needle rollers with crowned profiles, sorted by lot.View line Bearing seal with steel insert and rubber lip beside a sealed ball bearing showing the 2RS seal face BD-024Bearing sealsContact 2RS and low-friction 2RZ seals in NBR or FKM, fitted or loose.View line Metal shielded ball bearing with pressed steel ZZ dust cover next to an open bearing without covers BD-025Bearing shieldsPressed steel Z and ZZ shields for ball bearings: low friction, higher speed.View line Open bearing packed with bearing grease beside a grease cartridge and a sealed ball bearing BD-026Bearing greaseLithium, complex lithium, polyurea and food-grade H1 greases for ball bearings.View line Flat steel thrust washers and bronze thrust washer stacked beside a thrust ball bearing with its rings separated BD-027Bearing washersThrust shaft and housing washers, flat bronze or steel thrust washers and MB lock washers.View line Assorted bearing bushings including bronze sleeve, flanged and PTFE composite types on a workshop bench BD-028Bearing bushingsBronze, sintered, wrapped bimetal, PTFE composite and polymer bushings in sleeve, flanged and thrust forms.View line Cast iron bearing housings in pillow block and flange forms with a split plummer block housing on a bench BD-029Bearing housingsPillow block, flange, take-up and split housings in HT200, ductile iron, pressed steel or stainless.View line

The parts of a rolling bearing

A rolling bearing looks like one object but is built from a handful of precisely made parts. The inner ring fits the shaft and the outer ring fits the housing; both carry hardened raceways. Between them run the rolling elements - balls or rollers - kept apart by a cage. Many bearings add seals or metal shields on the faces and a fill of grease. Each part has its own material, its own tolerance and often its own maker, which is why a bearing is only as consistent as the weakest component in it.

Buying these parts separately makes sense in a surprising number of cases. A repair shop may replace only a worn cage or a set of balls. A maker of conveyor rollers or pulleys may assemble its own bearings from rings and balls. An OEM may buy turned rings and finish them in-house. A distributor that sells repair kits needs seals and shields in volume. The desk sources for all of these buyers; for finished bearings see the ball bearings and roller bearings hubs.

Components and what to specify

Bearing components and the main points to state when asking for a quote
ComponentTypical materialKey specificationPage
SteelGCr15 (52100, 100Cr6), carburizing steel, 440CGrade, cleanliness, form (bar, tube, wire)Bearing steel
RingsThrough-hardened or carburized steelDrawing, tolerance class, turned or groundBearing rings
CagePressed steel, brass, PA66-GF, phenolicType, pocket design, materialBearing cages
BallsChrome steel, stainless, ceramicDiameter, ISO 3290 gradeBearing balls
RollersChrome steelType, size, profile, sortingBearing rollers
SealsNBR, FKM rubber on a steel coreContact or non-contact, size to bearingBearing seals
ShieldsStamped steelZ or ZZ, size to bearingBearing shields
GreaseLithium, complex lithium, polyureaTemperature, speed, noise, base oilBearing grease

Dimensions of rings and cages are matched to a bearing designation, so the quickest way to ask is by designation plus the part you need - for example the cage for a given deep groove size. Nominal bearing sizes are listed in the size chart; always confirm against the drawing or supplier datasheet.

How the component supply chain is organised

Component making is a specialised, separate industry from bearing assembly. Industry analyses describe the Liaocheng cluster in Shandong, centred on Yandian in Linqing, as the largest cage production base in China and a trading market for bearing parts, with steel ball makers in the nearby Dong'e area, cage makers around Zhengjia town and seal makers around Guan county. Ring forging and turning is done by specialist plants close to the large bearing clusters, and rolling element makers often sit near the steel supply. This matters to a buyer: a plant that makes complete bearings usually buys its balls, cages and seals from these specialists, so sourcing the part directly can skip a step.

The desk uses this structure. For each program it shortlists a component maker by the part, the grade and the volume, asks for the material certificate and a sample lot, and arranges inspection before shipment. Read more about the clusters.

Matching parts to a bearing

A set of components only works as a bearing when the parts agree with each other. Three relationships matter most.

  • Ball or roller size and ring raceway. The rolling element diameter and the groove radius set the contact and the load share. Replacing balls with a different size or grade changes clearance and noise.
  • Cage and rolling elements. Pocket size and cage type must suit the rolling element and the speed; a cage swapped for another material changes friction and temperature limits.
  • Ring tolerance and internal clearance. Ring bore, outside diameter and raceway size decide the final radial clearance. See tolerance and clearance.

Ordering components

Components are normally counted in thousands: balls, cages and seals commonly start in the order of ten thousand pieces per specification, while turned rings are quoted from the drawing and a trial lot. Samples of standard parts typically ship in 3-7 working days and custom samples take 15-30 days. All of these are typical reference ranges and are confirmed in writing for each program. Inspection is agreed per lot - dimensions, hardness, surface and sorting for the part in question, as described under testing and inspection.

To start, send a drawing or designation, the material, tolerance class and annual quantity through the quote form. If you need the complete bearing rather than parts, the custom bearings page explains how drawings are handled.

Questions buyers ask

Who buys bearing components instead of finished bearings?

Bearing repairers, assemblers who build bearings in-house, makers of conveyor rollers and pulleys, and OEMs that finish their own rings. Distributors also buy seals and shields in volume for repair kits.

Can I buy only cages or only balls?

Yes. Cages, balls and rollers are sourced as separate parts, quoted by type, size and grade, and counted in thousands. The desk confirms quantity, packaging and inspection in writing for each program.

Do you supply a complete bearing from components I choose?

The desk can coordinate a partner plant to assemble from agreed parts, or supply a complete bearing to a designation. Tell us which route you prefer in the quote form.

How do I know a component will fit my bearing?

Fit is checked against the bearing designation, a drawing or measured samples. Standard sizes follow ISO dimensions, but pocket size, ball grade and ring tolerance should be confirmed against the datasheet before a volume order.

Do components come with material certificates?

Material certificates and inspection reports can be requested per lot, and are agreed before the order. See bearing steel for what a certificate normally covers.

Send the designations or d x D x B sizes you need, the quantity per item and your market. The desk replies in writing with matched options, inspection points and the reference MOQ.

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