ISO 12297-2:2018

Overview

ISO 12297-2:2018 - "Rolling bearings - Cylindrical rollers - Part 2" defines boundary dimensions, geometrical product specifications (GPS) and tolerance values for ceramic rollers (silicon nitride) used in rolling bearings. It is a machine-element geometry standard within the ISO GPS framework and covers nominal sizes, chamfer limits, roughness, run-out and lot-level sorting rules for finished ceramic cylindrical rollers.

Key topics and technical requirements

• Scope and material: Applies to finished silicon nitride cylindrical rollers for rolling bearings; material requirements reference ISO 26602.
• Dimensional data: Nominal roller diameters (D), lengths (L) and minimum/maximum chamfer radii (r_min, r_max) are tabulated for many common sizes (see Table 2 in the standard).
• Tolerances and grades: Roller grades (G20, G32, G40, G48, G60, G100) are defined with associated tolerance values for:
  • single-roller diameter tolerance (t_Dwmp),
  • lot diameter variation (VDwmp and VDwL),
  • outside-diameter roughness (Ramax),
  • axial circular run-out (SDw). Example values (from Table 3): G20 t ≈ 0.5 µm, Ramax 0.08 µm, SDw 6 µm; G100 t ≈ 2.5 µm, Ramax 0.2 µm, SDw 15 µm.
• GPS and measurement rules: The document follows ISO GPS principles (ISO 14638, ISO 8015) and uses default size operator per ISO 14405-1. Surface-roughness measurement follows ISO 4288; measurement uncertainty considerations reference ISO 14253-1/2.
• Sorting and gauges: Annex A and B provide sorting principles and gauge systems for roller diameter and length (roller diameter/length gauge lots, gauge intervals and example scales).
• Imperfection inspection: Annex C gives examples of imperfection types and recommended inspection methods; local defects and waviness limits are subject to customer‑supplier agreement.

Practical applications and who uses this standard

ISO 12297-2 is used to:

• Specify ceramic roller geometry and tolerances for engineering drawings and purchase orders.
• Define production and QA acceptance criteria in bearing manufacturing and subcontract machining.
• Configure metrology procedures and gauge selection in inspection labs.
• Support design engineers in high-speed, high-temperature or low-friction applications (automotive turbochargers, aerospace actuators, precision spindles, industrial machinery) where silicon nitride rollers are preferred.

Typical users: bearing manufacturers, quality/inspection engineers, procurement/specification writers, metrology labs, OEM design teams.

Related standards

• ISO 26602 - Silicon nitride materials for rolling bearing balls and rollers
• ISO 4288 - Surface texture: profile method
• ISO 14638, ISO 8015 - GPS framework and fundamental rules
• ISO 14405-1, ISO 14253-1/2 - Size specification and decision rules

Keywords: ISO 12297-2, ceramic rollers, silicon nitride, rolling bearings, GPS, tolerance values, roller dimensions, run-out, roughness, roller gauges.