ISO 12128:2020

Overview

ISO 12128:2020 - Plain bearings: lubrication holes, grooves and pockets - specifies standardized dimensions, types, designation and application rules for lubrication features in plain bearing bushes. The standard covers lubrication holes, longitudinal/circumferential grooves and lubrication pockets for solid and steel-backed plain bearing bushes made of copper alloys, aluminium alloys, thermosetting plastics, thermoplastics and artificial carbon. It clarifies how to indicate these features on drawings and how to assign lubricant feed and distribution types to common bush materials. (Sintered-metal bushes are excluded because they are typically soaked with lubricant; artificial carbon is not lubricated with oil or grease.)

Key topics and requirements

• Dimensioning basis: Lubrication feature dimensions are given relative to the bearing wall thickness (s); the diameter (d) is an auxiliary dimension.
• Lubrication holes: Defined types (e.g., A, B, L) with recommended sizes and designation examples (e.g., “Lubrication hole ISO 12128 – A3”).
• Lubrication grooves: Multiple groove types (C, D, E, F, G, H, J, etc.) with depth, width and shape guidance; closed-end and open-end variants are specified and labelled (example designation: “Lubrication groove ISO 12128 – D0,8”).
• Lubrication pockets: Type K pockets for larger lubrication reservoirs; pocket dimensions and designation (example: “Lubrication pocket ISO 12128 – K2,5”).
• Design rules:
  • Avoid placing holes/grooves in highly stressed zones.
  • Grooves/pockets generally should not extend the full bearing length (except artificial carbon exceptions).
  • Edges chamfered to max 0.5 mm or rounded; avoid sharp transitions.
  • Permissible deviations use tolerance class “c” per ISO 2768‑1.
  • For multiple holes, standard angular spacing applies (2 holes = 180°, 3 = 120°, 4 = 90°).
• Designation on drawings: The standard provides concise designation formats and examples for bushes incorporating these features and how symbols x (distance from insert side) and h (groove pitch) are used.

Applications and users

ISO 12128:2020 is directly useful for:

• Mechanical and design engineers specifying bearing bushes
• OEMs and machine designers requiring reliable lubricant feed solutions
• Bearing manufacturers and machine shop drawing authors
• Maintenance engineers selecting or replacing plain bearings
• Technical drafters preparing ISO-compliant drawings

Practical uses include designing lubrication paths for journal bearings, slideways and bushings in engines, pumps, construction equipment and industrial machinery where controlled lubricant feed and retention are required.

Related standards

• ISO 4379 (Copper alloy bushes) - often used together for material/dimension specs
• ISO 4383 (Multilayer materials for thin-walled plain bearings)

Keywords: ISO 12128:2020, plain bearings, lubrication holes, lubrication grooves, lubrication pockets, bearing bushes, bearing wall thickness, lubrication designation.