ISO 4386-1:2019

Overview

ISO 4386-1:2019 specifies a non‑destructive ultrasonic testing (NDT) method for detecting bond defects in metallic multilayer plain bearings. It covers bearings with steel- or copper‑based backings lined with lead‑ or tin‑based bearing metal where the lining thickness is ≥ 0.5 mm. The document describes the pulse‑echo ultrasonic technique (qualitative only) to distinguish between a sound bond and a bond defect; it does not quantify bond strength.

Key topics and technical requirements

• Scope & materials: Applicable to steel- and copper-based backings; limited applicability to cast iron backings. Lining thickness ≥ 0.5 mm. Dovetail edges and small edge zones (within half the probe diameter) are excluded due to undefined reflections.
• Testing method: Pulse‑echo ultrasonic inspection using a rectified A‑scope display. The method relies on the ultrasonic signal reflected at the bond interface (bond echo and back‑wall echo).
• Equipment:
  • Ultrasonic instrument with calibrated attenuator (dB) and adjustable time base.
  • Normal‑beam probes sized to layer/backing thickness and material (typical diameters ~24 mm at 2 MHz down to 6 mm at 10 MHz). Dual‑element probes may be used for layer thickness < 1 mm.
  • Reference block matching the test geometry for time‑base and sensitivity adjustment.
• Surface and coupling: Test surface roughness Ra ≤ 5 µm; clean of dirt/oil. Contact scanning (light machine oil couplant) or immersion scanning permitted. Suppression and swept‑gain functions must be off.
• Procedures:
  • Testing with back‑wall echo: adjust so back‑wall echo ~80% screen height; bond defect indicated by breakdown of back‑wall echo and increase/repetition of bond echo.
  • Testing without back‑wall echo: adjust reference bond echo to 20% full screen height and compare.
• Evaluation & acceptance:
  • Qualitative pass/fail (bond vs defect). Defects generally estimated at ≥ half probe diameter.
  • Test classes 1–3 define increasing coverage (from point‑type coverage to full line‑by‑line scanning with 20% probe overlap).
  • Defect groups (A–D) and maximum single/total defect sizes are defined and must be agreed between supplier and customer.
• Limitations: Edge transitions are evaluated by penetrant testing per ISO 4386‑3.

Applications and users

• Who uses it: NDT technicians, bearing manufacturers, quality assurance engineers, maintenance teams, and suppliers/customers specifying acceptance criteria for multilayer plain bearings.
• Practical uses: Incoming inspection of lined bearings, production quality control, post‑repair verification (e.g., after soldering), and root‑cause analysis for bond failures.

Related standards

• ISO 4386-3: Non‑destructive penetrant testing for visible transitions (end faces / joint faces).
• Prepared by ISO/TC 123 (Plain bearings), Subcommittee SC 2.

Keywords: ISO 4386-1:2019, plain bearings, metallic multilayer, ultrasonic testing, pulse‑echo, NDT, bond defects, bearing lining inspection.