Overview
ISO/TS 24137:2023 - "Plain bearings - Surface modification by press fitting solid lubricants combined with micro dimple processing" specifies a practical, mass-production-capable method to improve the friction characteristics of plain bearing surfaces. The Technical Specification defines a combined process in which a solid lubricant is mechanically press-fitted into a metal surface that has been textured with many micro dimples, producing a thin (micrometer-scale) modified layer firmly bonded to the base metal.
Key Topics and Requirements
- Scope: Surface modification method for plain bearings to enhance friction and wear performance. Target materials are metallic bearing substrates (e.g., steel, aluminium alloy, titanium alloy), especially those with high work-hardening properties.
- Solid lubricants: Typical candidates include molybdenum disulfide (MoS2), graphite, and carbon black, chosen by application (high load, high temperature, dry/low-humidity environments).
- Process steps:
- Formation of micro dimples (surface texturing)
- Supply/coating of solid lubricant (suspended in a solvent and applied to the dimpled surface)
- Press fitting of the lubricant into the dimples (mechanical smoothing/embedding)
- Dimple formation methods:
- Shot peening (including hybrid media pre-coated with lubricant), with recommended shot diameter ~5× expected dimple diameter, media hardness ≈ 70% of target material, projection flow ≈ 5 g/s and projection pressure ≈ 0.3 MPa. Use Almen strips/arc height to evaluate intensity.
- Interrupted micro cutting for controlled dimple patterns, pitch and depth-suitable for internal surfaces and high homogeneity.
- Press fitting methods: Roller burnishing is recommended to smooth the plateau and press-fit lubricant; suggested contact surface pressure ≈ 1.5–2.5 GPa for aluminium, steel and titanium alloys.
- Safety note: Solvents used to carry solid lubricant are volatile and flammable - follow GHS labelling and handling guidance.
- Performance data: Annex A shows ball-on-disc friction testing with MoS2-treated aluminium alloy demonstrating lower friction and longer life compared with untreated surfaces.
Applications
- Manufacturers of plain bearings, bushings and sliding components seeking improved dry or boundary lubrication performance.
- Tribology and surface-engineering teams in automotive, aerospace, industrial machinery, and vacuum or high-temperature systems.
- Processes suited for mass production where adhesion and longevity of solid-lubricant films are critical and where simple, equipment-light methods are preferred.
Related Standards
- Shot peening standards referenced for general procedure: ISO 12686 and ISO 26910-1.
- For terminology and broader plain-bearing standards, consult ISO/TC 123 outputs and ISO Online Browsing Platform.
Keywords: ISO/TS 24137:2023, plain bearings, surface modification, press fitting solid lubricants, micro dimple processing, molybdenum disulfide, shot peening, roller burnishing, tribology.