ISO 3548-3:2023

Overview

ISO 3548-3:2023 - Plain bearings - Thin-walled half bearings with or without flange - Part 3: Determination of the peripheral length - defines how to check and measure the peripheral length of thin-walled half bearings. The standard recognizes that these flexible half bearings do not keep a cylindrical shape in the free state, so peripheral length measurement must be performed under a constraining load with specialized measuring equipment. The document describes measurement methods, gauging tools, correction factors and accuracy requirements for reliable peripheral length determination.

Key Topics and Requirements

• Measurement principle: Peripheral length is the circumferential length between parting line faces and must be measured under a constraining load to produce repeatable results.
• Measurement methods: Two principal checking methods are specified (Method A and Method B). The standard covers selection, designation and procedural differences between them.
• Measuring equipment requirements: Detailed requirements include tolerance on checking load setting, speed of approach of the measuring head, construction of the measuring head, accuracy of metering bars and dial gauges, and general instrument accuracy. Alternative equipment is permitted if it meets the accuracy limits in Clause 17.
• Gauging tools and datum establishment: Definitions and requirements for master checking blocks, series checking blocks, master shells and comparison shells used to establish the measurement datum.
• Correction factors and marking: Procedures to determine and apply correction factors for reference tooling (master blocks, series tools, shells) are described, including acceptable wear limits and marking conventions.
• Errors and uncertainty: Identification of error sources (measuring equipment, checking block, correction factor, half bearing behavior, and choice of method) and guidance on repeatability, reproducibility and comparability (Annex E).
• Documentation and control: Specifications to be included on bearing drawings and procedures for control and verification of checking means.

Applications and Who Uses It

ISO 3548-3:2023 is intended for:

• Manufacturers of plain bearings and thin-walled half bearings who need standardized dimensional control.
• Quality assurance and metrology engineers responsible for peripheral length measurement and inspection.
• Tooling and inspection equipment designers supplying master/series checking blocks and shells.
• Procurement, design and maintenance teams specifying bearing tolerances and production acceptance criteria.

Practical benefits include consistent peripheral length measurement, reduced measurement uncertainty, improved interchangeability and documented inspection procedures for production and incoming inspection.

Related Standards

• ISO 3548-1 - Thin-walled half bearings: tolerances, design features and methods of test (applies to the part geometry covered by ISO 3548-3).
• ISO 12301 - Quality control techniques and inspection of geometrical and material quality characteristics (referenced for checking methodology).

Keywords: ISO 3548-3:2023, thin-walled half bearings, peripheral length measurement, plain bearings, checking methods, measuring equipment, correction factor, master checking block.