Overview
ISO 4385:1981 specifies a standardized method for compression testing of metallic bearing materials used in plain bearings. The standard defines how to determine the behaviour of metallic bearing alloys under uniaxial compression that is uniformly distributed over the cross‑section. Testing is performed on cylindrical specimens that are slowly and continuously loaded in compression while force and deformation are recorded to derive compressive strength and defined compressive limits (for example the 0.2 % and 2 % offsets).
Key topics and technical requirements
- Specimen geometry and preparation
- Cylindrical specimens, preferred diameter 20 mm; height/diameter ratio h0/d0 = 1.
- End faces to be finely polished or ground and perpendicular to the axis; fully machined surfaces.
- Diameter d0 and height h0 measured to 0.1 mm accuracy.
- Test equipment
- Use compression testing machines with planed and ground pressure plates (minimum hardness 60 HRC).
- Pressure plates lightly greased (e.g., petroleum jelly).
- Differential‑length measuring device accuracy 0.01 mm (or 10 % whichever is larger for limit determination).
- Measurements and definitions
- Compressive stress = F / S0; compressive strength = Fmax / S0.
- Compressive limits: 0.2 % (Od0.2) and 2 % (Od2) permanent compression offsets; natural compressive yield point OdF if applicable.
- Draw compressive stress–compression curves; determine limits using a line parallel to Hooke’s law or via hysteresis-centre-line method when necessary.
- Procedure and rates
- Load continuously and slowly; for strength determination, increase stress at a maximum of 30 N/(mm²·s) until fracture or specified total compression (note: total compression should not exceed 50 %).
- Options for measuring permanent deformation include removing load and measuring height change or using a preforce procedure.
- Test report requirements
- Include reference to ISO 4385, specimen dimensions and manufacture, measurement method, lubricant, test temperature (±1 °C), and reported values (compressive strengths, limits, deformation percentages, etc.).
Applications and users
ISO 4385 is directly applicable to:
- Manufacturers of plain bearings and bearing alloys for quality control and material specification.
- Metallurgical labs and independent testing laboratories performing mechanical characterization.
- R&D and materials engineering teams assessing bearing material deformation, bulging and fracture behaviour.
- OEMs and quality assurance personnel requiring reproducible compressive property data for design validation and supplier verification.
Keywords: plain bearings, compression testing, metallic bearing materials, compressive strength, 0.2% compressive limit, bearing alloys, test specimen, ISO 4385.
Related standards
ISO 4385 was developed by ISO/TC 123 (Plain bearings). Users should consider complementing this method with other ISO or national standards covering metallurgical sampling, hardness, and full mechanical testing procedures applicable to bearing materials.
