Overview
ISO 14728-2:2017 - "Rolling bearings - Linear motion rolling bearings - Part 2: Static load ratings" defines standardized methods to calculate the basic static load rating, static equivalent load, and static safety factor for linear motion rolling bearings. The standard applies to bearings made from contemporary hardened bearing steel and of conventional rolling-contact geometry. It is not applicable where rolling elements run directly on a machine slide surface unless that surface is fully equivalent to a bearing raceway.
Key Topics
- Scope and applicability: Calculation methods for common linear ball and roller bearing designs (recirculating sleeve and carriage types, non‑recirculating deep-groove, four‑point, flat/V-angle/crossed roller guideways).
- Basic static load rating (C0): Defined using contact-stress criteria that correspond to an acceptable permanent deformation (≈0.0001 of rolling-element diameter). The document provides formulae, factors and tables for different geometries and arrangements.
- Contact stress values: Reference contact stresses used in calculations (e.g., 5 300 MPa for recirculating sleeve ball bearings; 4 200–4 600 MPa for linear guideway ball types; 4 000 MPa for roller bearings).
- Static equivalent load (P0): Method to convert actual loads and load directions into a single equivalent static load for rating checks.
- Static safety factor (S0): Ratio of basic static load rating to static equivalent load, used to assess the margin against inadmissible permanent deformation.
- Symbols, figures and tables: Standardized notation, geometric definitions (pitch diameter, contact angle), and lookup tables (k, f, contact stress) to support consistent calculations.
Applications
ISO 14728-2:2017 is essential for:
- Bearing designers and manufacturers calculating static ratings for linear guides and carriages.
- Machine design and mechanical engineers sizing linear motion components in machine tools, robotics, automation, actuators and precision equipment.
- Quality, reliability and safety engineers assessing permissible static loads and selecting appropriate safety factors.
- Procurement and standards compliance teams ensuring components meet internationally recognized static load-rating practices.
Practical benefits include consistent bearing selection, reduced risk of permanent deformation under static loads, and improved interchangeability across suppliers.
Related Standards
Using ISO 14728-2:2017 helps ensure repeatable, defensible static-load calculations for linear motion rolling bearings and supports robust mechanical system design.
