ISO 20120:2025

Overview

ISO 20120:2025 specifies a standardized laboratory method to measure the coefficient of friction and its evolution for synchronizers lubricated by manual transmission fluids (MTF) using a high‑frequency, linear‑oscillation (SRV) test machine. The method uses a flat areal contact (flat‑on‑flat) geometry and a translatory oscillation apparatus to reproduce the tribological interactions typical of manual‑gear synchronizer interfaces. ISO 20120 is intended as a rapid, high‑precision evaluation tool to screen lubricant formulations and materials prior to full bench or vehicle testing.

Key topics and technical requirements

• Test principle: Oscillating upper and lower flat specimens with lubricant between them; lateral friction force is vibration‑compensated and used to compute the coefficient of friction (peak‑to‑peak per cycle).
• Typical test parameters (documented defaults):
  • Normal force: 260 N (≈ 3.1 MPa contact pressure)
  • Oscillation frequency: 50 Hz
  • Stroke length: 1.0 mm
  • Test temperature: 60 °C (optionally 80 °C)
  • Test duration: 2 h
• Equipment: SRV translatory oscillation apparatus (SRV models 4 and 5, horizontal configuration). Load capability and optional cooling/heating and environmental monitoring are addressed.
• Specimen geometry and preparation: Flat ring disk and lower disk specimens with defined surface parameters; cleaning using non‑chlorinated, non‑film‑forming solvents per DIN 51631.
• Data acquisition & reporting: Sample rates and channels for friction/time/temperature are specified; calibration, inspection, cut‑off criteria for friction and required test report details are included.
• Precision: Repeatability and reproducibility clauses are provided; users are advised to validate correlation with real‑world performance.
• Safety and materials: Warnings on solvents and machine noise; adherence to machine operator training.

Practical applications and intended users

• Lubricant formulators screening MTF candidates for synchronizer friction behavior.
• Automotive OEMs and tier‑1 suppliers evaluating material/coating combinations for synchronizer rings.
• Independent test laboratories performing comparative friction testing and quality control.
• Tribologists and R&D teams using SRV tribometry to accelerate development cycles and reduce reliance on longer bench tests (e.g., ASTM D5579, CEC L‑66‑99).
• The method is particularly useful for rapid filtration of formulations to identify promising MTFs before committing to full component or vehicle homologation tests.

Related standards and references

• IEC 60751 (platinum resistance thermometers)
• DIN 51631 (special‑boiling‑point spirits - cleaning solvents)
• ASTM D5579, CEC L‑66‑99 (synchronizer bench tests)
• ASTM D8227‑20 (source material referenced)

Keywords: ISO 20120, synchronizer lubricants, manual transmission fluids (MTF), coefficient of friction, SRV test, high‑frequency linear oscillation, tribology, transmission lubricant testing.