Ball vs Bushing Bearings for ISO 492 Tolerance Specs

Key Takeaways

• Ball bearings use rolling contact for lower friction and higher speed; bushings use sliding contact for shock, contamination, and oscillating duty.
• For a 3–200 mm bore range, rolling bearings offer tolerance classes P0, P6, P5, and P4 with clearances C2, CN, C3, and C4, while bushing fits follow ISO 286.
• Load direction, speed, misalignment, and lubrication access determine whether a ball bearing or plain bushing is the correct specification.
• The plain bearing market was estimated at USD 13.55 billion in 2024, and the overall bearings market at USD 50.16 billion in 2025, indicating strong replacement demand.
• Send the bearing part number or bushing drawing plus duty data to receive a confirmed quotation within 24 hours.

Ball Bearings vs Bushing Bearings: Answer-First Definitions

A ball bearing uses hardened steel or ceramic balls rolling between an inner and outer ring to carry combined radial and axial loads with low starting friction. A bushing, or plain bearing, is a single cylindrical or flanged sleeve that supports a shaft through sliding contact, carrying primarily radial load and limited axial load when a flange or thrust face is present. The global bearings market was valued at $50.16 billion in 2025, according to Fortune Business Insights, while the plain bearing segment alone was estimated at USD 13.55 billion in 2024, per SNS Insider. Specifying the correct type requires matching load direction, speed, duty cycle, and environmental contamination to the bearing’s operating envelope.

Specification Snapshot for Both Types

• Ball bearing boundary dimensions: d × D × B (bore × outside diameter × width), e.g., 6204-2RS = 20 × 47 × 14 mm. Bore range 3–200 mm.
• Bushing boundary dimensions: d × D × L (bore × outside diameter × length), with flanged variants adding flange diameter and thickness. Bore range matched to 3–200 mm shaft sizes.
• Tolerance classes: Ball bearings available in P0, P6, P5, P4 (ISO 492). Bushings specified by bore tolerance, commonly H7 or E7 for the bushing ID, with housing fits per ISO 286.
• Radial internal clearance: Ball bearings in C2, CN, C3, C4. Bushings use running clearance between shaft and bushing bore, set by shaft tolerance (e.g., f7 or g6) rather than an internal clearance class.
• Cage material: Stamped steel, machined brass, or glass-fiber reinforced polyamide (TN9) for ball bearings. Bushings have no cage; sliding layer is bronze, PTFE composite, or solid polymer.
• Sealing arrangement: Open, ZZ (metal shields), 2RS (contact rubber seals), 2RZ (non-contact rubber seals) for ball bearings. Bushings may be unsealed with external shaft seals or feature integrated lip seals on flanged variants.
• Material grade: GCr15/100Cr6 through-hardened steel, AISI 440C or 316 stainless, Si3N4/ZrO2 ceramic for ball bearings. Bushings use bronze alloys, PTFE-lined steel backing, or solid polymer and composite materials.
• Applicable standards: Ball bearings to ISO 15, ISO 355, ISO 492, ISO 281, ISO 76. Bushings to ISO 3547 (wrapped), ISO 4379 (solid), and ISO 12128 (plain bearing tolerances), with dimensional fits per ISO 286.

Series and Internal-Design Variants

Ball bearings split into dimension series (e.g., 60, 62, 63, 69) that trade radial capacity against axial space. Deep groove ball bearings accept some axial load; angular contact ball bearings use a defined contact angle (confirm per part number) to increase axial capacity, and available as single- or double-row. Self-aligning ball bearings tolerate misalignment through a spherical outer ring raceway. Cylindrical roller bearings use ribs on inner or outer rings to control axial displacement. Bushing variants include cylindrical, flanged, and thrust washer types, plus spherical plain bearings for oscillating misalignment. The key design lever for a bushing is the length-to-diameter ratio and the sliding material layer, not row count or contact angle.

Reading Dynamic and Static Load Ratings (ISO 281 and ISO 76)

For rolling bearings, the basic dynamic load rating C is the constant load a bearing can endure for a rating life of one million revolutions, per ISO 281. The basic static load rating C0, per ISO 76, is the load that produces a permanent deformation of rolling element and raceway equal to 0.0001 times the rolling element diameter. These values are published per part number and must be de-rated for temperature above 120 °C or contaminated lubrication. For bushings, load capacity is not a single C value but a pressure-velocity (PV) limit: the product of bearing pressure and sliding speed that the material system can sustain without excessive wear or heat. Confirm C, C0, and limiting speed against the specific part number, duty cycle, and lubrication condition.

Sealing, Cage and Lubrication Options

Ball bearings with ZZ shields keep grease in and coarse contaminants out but allow higher speed than 2RS contact seals. 2RS suits wet or dusty environments; 2RZ offers lower friction with better sealing than shields. Cage selection follows speed and temperature: steel for general use, brass for high loads and shock, polyamide for quiet high-speed operation up to about 120 °C continuous. Grease fill and type (e.g., lithium complex, polyurea) are specified at assembly. Bushings require either external grease or oil supply, or use a self-lubricating PTFE or polymer liner that eliminates relubrication but limits PV. Solid bronze bushings with graphite plugs are an intermediate option for high-temperature or inaccessible locations.

Shaft and Housing Fits, Mounting and Clearance

For a rotating shaft with stationary housing, ball bearings typically use an interference fit on the shaft (j5, k5, or m5 depending on load) and a clearance or transition fit in the housing (H7, J7). If the outer ring rotates, the housing fit becomes interference (K7, M7) and the shaft fit looser. Internal radial clearance C3 is often selected for hot shafts or interference fits that reduce clearance after mounting. Bushings are pressed into a housing with an interference fit (H7 housing, r6 or s6 bushing OD) and the shaft runs with a calculated clearance, e.g., H7/g6 for precision sliding or H7/e7 for higher speed and thermal expansion. No preload applies to bushings; ball bearings may use axial preload on angular contact or spindle bearings to raise stiffness and reduce runout.

Interchange and Part-Number Suffix Decoding

Ball bearing part numbers follow boundary dimension series plus suffixes: ZZ for two metal shields, 2RS for two contact rubber seals, C3 for radial internal clearance greater than normal, P5 for ISO class 5 running accuracy, M for machined brass cage, TN9 for glass-fiber reinforced polyamide cage. A 6205-2RS/C3 is a deep groove ball bearing with rubber seals and C3 clearance. Bushing part numbers may follow ISO 3547 wrapped-bush designations or manufacturer codes that encode material, bore, and length. When interchanging, match boundary dimensions, tolerance class, clearance, and sealing arrangement rather than assuming the same suffix maps identically across suppliers.

Typical Industrial Applications

Ball bearings suit electric motors, fans, pumps, gearboxes, and machine tool spindles where low friction, high speed, and combined load capacity matter. Bushings suit conveyors, agricultural machinery, lifting equipment, and dirty or oscillating applications where compact size, shock tolerance, and maintenance-free operation are priorities. The plain bearing market size of USD 13.55 billion in 2024, according to SNS Insider, reflects this installed base in material handling and process equipment where sliding contact remains the correct engineering choice.

Ordering Data and Documentation Required

To specify a ball bearing, send the full part number and suffix, or boundary dimensions, load, speed, temperature, and sealing needs. For a bushing, send the shaft diameter, housing bore, length, load direction, PV duty, and whether relubrication is possible. Samples and packaging are confirmed per enquiry against the part number, quantity, and destination.

Request a Tailored Quotation

Send the bearing part number, bushing drawing, or duty data including radial and axial load, speed, operating temperature, and contamination level. Engineering confirmation of dimensions, tolerance class, clearance, and lubrication will be returned with the quotation.

Bushing Bearings vs Ball Bearings: Direct Selection Answer

For industrial duty within a 3–200 mm shaft diameter, specify a rolling ball bearing when low starting torque, high rotational speed, and predictable radial or combined load capacity are the controlling factors. Specify a plain bushing when the application involves oscillating or slow sliding motion, shock loads, contamination, or a need for a compact, maintenance-tolerant bearing surface. The two types are not interchangeable: one replaces rolling friction with sliding contact, and that change governs speed, wear, clearance, and fit strategy.

Key Facts: Bushing and Ball Bearing Specification

• Bearing type: deep groove ball bearing (rolling) vs cylindrical or flanged plain bushing (sliding).
• Bore range: 3–200 mm for both rolling bearings and bushings in the published catalog.
• Tolerance class: P0, P6, P5, P4 for rolling bearings per ISO 492; bushing fits are set by shaft and housing tolerances per ISO 286.
• Radial internal clearance: C2, CN, C3, C4 for rolling bearings; bushing running clearance is controlled by the selected fit.
• Cage material: steel, brass, or polyamide for ball bearings; bushings use a solid bronze, PTFE-lined, or polymer sliding surface.
• Sealing arrangement: open, ZZ, 2RS, or 2RZ for ball bearings; bushings may be relubricated through a groove or used dry where PTFE is present.
• Material grade: GCr15/100Cr6, AISI 440C, AISI 316, Si3N4 or ZrO2 for ball bearings; bronze, PTFE-lined steel, or polymer for bushings.
• Applicable standards: ISO 492, ISO 15, ISO 281, ISO 76, ISO 286 and ISO 5753 for ball bearings; ISO 12240-1 for spherical plain bearings and ISO 286 for plain bushings.

Selection Parameters Engineers Should Compare

Load direction is the first filter. A deep groove ball bearing carries radial load and moderate axial load in both directions, while an angular contact ball bearing is required for dominant unidirectional axial load. A cylindrical bushing carries radial load only unless a flange is specified. For combined misalignment and oscillating motion, a GEH ES Series Extra Thick Spherical Plain Bearings — DIN ISO 12240-1 is often the correct choice because the sliding spherical surface tolerates angular error without inducing edge loading.

Speed capability separates the two types more than any other parameter. Ball bearings operate with rolling contact and can sustain higher shaft speeds with lower heat generation. Bushings generate heat in proportion to PV (pressure × velocity), so they suit lower-speed, higher-load, or oscillating duties. For catalog dimensions of a common radial ball bearing, refer to 6200 Series Deep Groove Ball Bearings — ISO 15 / DIN 625-1 / GB/T 276.

Fit strategy differs. A ball bearing uses an interference fit on the rotating ring and a clearance or transition fit on the stationary ring, selected from ISO 286 tolerance grades. A bushing uses a controlled clearance between the shaft and the sliding surface, which becomes the running clearance. Both approaches require the shaft and housing tolerances to be specified together; the 15 free engineering calculators on the site can check basic rating life for a ball bearing or PV pressure-velocity for a bushing.

The installed base for both technologies is substantial: the plain bearing market was estimated at USD 13.55 billion in 2024 according to SNS Insider, and the overall bearings market was valued at USD 50.16 billion in 2025 according to Fortune Business Insights. For B2B specifiers, this means replacement demand and standardization matter, so bearing type selection should be consistent across a machine platform.

Send the bearing part number, bushing drawing, or duty data including radial and axial load, speed, operating temperature, and contamination level. Engineering confirmation of dimensions, tolerance class, clearance, and lubrication will be returned with the quotation within 24 hours.

Data sources: fortunebusinessinsights.com · snsinsider.com