Overview - ISO 23848-2:2009 (Ball splines, load ratings & rating life)
ISO 23848-2:2009 specifies how to calculate basic dynamic load ratings, basic static load ratings, and basic rating life for machine-tool ball splines (types AI, AII and R). The part also establishes basic dynamic and static torque ratings and defines key terms such as the L10 (90 % reliability) rating life. This standard supports consistent design, selection and life prediction for ball splines used where axial translation and torque transmission are required.
Key topics and technical requirements
- Scope and definitions: Clear definitions for basic dynamic load rating (C), basic static load rating (C0), basic dynamic/static torque ratings (CT, C0T), dynamic/static equivalent loads and L10 life (90 % survival probability).
- Calculation methods: Explicit formulae for:
- Basic dynamic load rating and torque rating for angular types (AI, AII) and radial type (R).
- Basic static load and torque ratings.
- Rating life (L10) for applied radial load and for applied torque (life expressed via the relationship between C and equivalent load/torque).
- Factors and parameters: Tables and expressions for geometry- and arrangement-dependent factors (f, f0, k, k0), contact angles, effective number of balls (Z), groove geometry (r/D), ball pitch diameter (D), and adjustment factors (for example b = 1.3 and λ = 0.9 appear in the calculation framework).
- Contact stress guidance: Reference tables linking groove geometry to maximum contact stress (σmax) used to determine static ratings.
- Illustrations: Diagrams of load/torque directions and contact angles for type AI, AII (angular) and type R (radial).
Practical applications and users
- Design engineers and machine-tool component designers use ISO 23848-2 to size and specify ball splines for linear motion systems that must also transmit torque.
- Manufacturers of ball splines and linear actuators apply the calculation methods and tables to certify product ratings.
- System integrators, procurement and quality engineers use the standard to compare suppliers, verify rating life claims, and ensure compatibility with machine-tool requirements.
- Test laboratories and reliability analysts use the L10 methodology to predict service life under specified loads and torques.
Related standards
- ISO 23848-1 - Machine tools - Ball splines: Characteristics, shapes and dimensions (normative reference).
- ISO 14728-1 / ISO 14728-2 - Rolling bearings for linear motion: dynamic and static load ratings and rating life (related bearing life methodology).
Keywords: ISO 23848-2, ball splines, machine tools, dynamic load rating, static load rating, rating life, torque rating, L10 life, ball spline design.
Open preview (PDF)Machine tools — Ball splines — Part 2: Dynamic and static load ratings and rating life