ISO 230-4:2022

Overview

ISO 230-4:2022 - Test code for machine tools - Part 4: Circular tests for numerically controlled machine tools - defines standardized methods to determine the contouring performance of numerically controlled (NC) machine tools. The standard specifies how to test and evaluate circular paths produced by coordinated movements of two or more axes (linear and/or rotary), including the measurement and reporting of bi-directional circular error, mean bi-directional radial error, circular error, and radial error. It complements ISO 230-1 and is part of the ISO 230 series for machine tool testing.

Key technical topics and requirements

• Test scope and definitions: Clear terminology for nominal and actual paths, circular error (G), bi-directional circular error (G(b)), radial error (F) and mean bi-directional radial error (D).
• Test conditions: Requirements for test environment, machine warm-up, machine selection for testing, and agreed test parameters.
• Measurement and instrumentation:
  • Calibration of test instruments and handling of measurement uncertainty.
  • Use of external measurement equipment or feedback signals (Annex E) for circular tests.
• Test procedures and results: Prescribed procedures for executing circular tests (full or partial circles ≥ 90°), presenting results, and items to be agreed between supplier/manufacturer and user.
• Annex guidance:
  • Annex A - differences between circular and radial errors.
  • Annex B - influences of typical machine errors on circular paths with two linear axes.
  • Annex C - precautions for set-ups when rotary axes are included.
  • Annex D - example of adjusting diameter and contouring speed.
  • Annex E - circular tests using feedback signals.

Practical applications and users

ISO 230-4:2022 is practical for:

• Machine tool manufacturers validating NC interpolation and multi-axis coordination.
• OEMs and system integrators specifying machining accuracy and accepting deliveries.
• Metrology and test laboratories performing standardized circularity and contouring tests.
• Quality engineers and maintenance teams diagnosing contouring errors and planning corrective adjustments.
• Process engineers and NC programmers evaluating the effect of feedrate, interpolation mode and axis coordination on circular trajectories.

Typical uses include verifying circularity and radial deviations for precision components, assessing the impact of rotary axes on tool/workpiece relative position, and comparing machine performance across machines or after repairs.

Related standards

• ISO 230-1:2012 - Test code for geometric accuracy (normative reference).
• Other parts of the ISO 230 series that address static and dynamic test methods for machine tools.

Keywords: ISO 230-4:2022, circular tests, machine tools, numerically controlled, contouring performance, circular error, radial error, bi-directional error, rotary axes, test procedure, measurement uncertainty.