Overview
ISO 3547-6:2020 - Plain bearings - Wrapped bushes - Part 6: Checking the inside diameter - specifies accepted methods and measuring equipment for checking the inside diameter of wrapped bushes. Following ISO 12301 and referring to ISO 3547-2 (method C), this standard explains how to transform a flexible free bush into a measurable condition (by pressing it into a ring gauge) and how to determine the inside diameter using mechanical gauges or measuring instruments. All dimensions are given in millimetres unless otherwise noted.
Key topics and requirements
- Purpose: Because wrapped bushes are flexible, the free diameter is not measured directly; the bush is pressed into a ring gauge whose nominal diameter corresponds to the housing bore (typically H7 tolerance).
- Measuring methods:
- Three-point measuring instrument (radial measurement using spherical pin faces).
- GO / NO-GO plug gauges: GO plug should insert with minimum effort; NO-GO must not insert under a maximum force (standard default 250 N, but the limit may be agreed between supplier and user).
- Alternative methods (subject to correlation): cylindrical gauges, dial gauges, optical devices.
- Test equipment:
- Ring gauge and plug gauge dimensions and wear limits specified (see standard tables).
- Gauges must be made from hardened, non-ageing steel (60–64 HRC).
- Measurement considerations and error sources:
- Damage/wear to ring or plug gauges, lack of lead-in chamfer, misalignment during insertion, insufficient ring width, contaminants (grease, burrs), and swelling of parts.
- Agreement between supplier and user:
- Decide whether results are recorded by measuring or by gauging, and agree on any force limits, special dimensions (for D > 180 mm), or deviations from default gauges.
Applications and users
Who uses ISO 3547-6:2020:
- Quality engineers and inspection technicians in bearing and bush manufacturing.
- Metrology and QA teams in automotive, industrial machinery, hydraulic and pivot applications where wrapped bushes are used.
- Suppliers and purchasers negotiating inspection protocols and acceptance criteria.
Practical benefits:
- Ensures consistent, reproducible inside-diameter checks across suppliers and users.
- Reduces measurement disputes by defining gauges, wear limits and common error sources.
- Integrates with plant quality-control procedures (ISO 12301) for geometrical inspection.
Related standards
- ISO 3547-1:2018 - Dimensions of wrapped bushes
- ISO 3547-2:2017 - Test data for outside and inside diameters (method C referenced)
- ISO 3547-5 - Checking the outside diameter
- ISO 3547-7 - Measurement of wall thickness of thin-walled bushes
- ISO 12301 - Quality control techniques for plain bearings
Keywords: ISO 3547-6:2020, plain bearings, wrapped bushes, inside diameter checking, ring gauge, plug gauge, three-point measuring instrument, GO NO-GO, H7 tolerance, inspection procedure.
