ISO 230 Standards Reference
The "Bible" of machine tool accuracy. A cheat sheet for the entire ISO 230 series, from Geometric Accuracy to Thermal Distortion.
Why ISO 230 Matters
When buying a high-end CNC machine (DMG Mori, Makino, Okuma), the acceptance tests are based on ISO 230. Lower-end builders often cite JIS B 6336 or VDI/DGQ 3441 because they use fewer target positions and simpler evaluation methods.ISO 230 is the gold standard for truth in accuracy.
ISO 230 Series Breakdown
| Standard | Title / Focus | Key Tests & Description | Primary Tool |
|---|---|---|---|
| ISO 230-1 | Geometric Accuracy | Straightness, Flatness, Squareness, and Parallelism of axes. Done under "No Load". | Granite Square, Level |
| ISO 230-2 | Positioning Accuracy | The "Big One". Determines Positioning Accuracy (A), Repeatability (R), and Backlash (B). | Laser Interferometer |
| ISO 230-3 | Thermal Effects | Measures axis drift due to environmental temperature changes and spindle heat generation. | Displacement Sensors |
| ISO 230-4 | Circular Tests | Dynamic contouring accuracy. Identifies servo mismatch, reversal spikes, and stick-slip. | Telescoping Ballbar |
| ISO 230-5 | Noise Emission | Sound pressure levels during operation. | Decibel Meter |
| ISO 230-6 | Diagonal Displacement | Volumetric accuracy check by moving along body diagonals (Body Diagonal Test). | Laser Tracer |
| ISO 230-7 | Rotational Axes | Geometric accuracy of rotary tables (A, B, C axes). Center of rotation error. | Test Arbor / Laser |
Deep Dive: ISO 230-2
Understanding A, R, and B values.
ISO 230-3 (Thermal)
Coming Soon: How to test thermal drift.
Related Calculators
Use these calculators when machine-tool accuracy standards need to feed back into procurement, maintenance, or lifecycle cost decisions.
Compare machine options once ISO 230 acceptance requirements and axis-accuracy needs are defined.
Budget service, calibration, and downtime exposure around the machine accuracy level you need to sustain.
Add accuracy-driven maintenance, verification, and service assumptions to the ownership model.
Frequently Asked Questions
What is ISO 230 and what does it cover?
ISO 230 is a family of standards for testing geometric accuracy and positioning of CNC machine tools. ISO 230-2 covers linear axis positioning accuracy, ISO 230-4 covers circular tests, and ISO 230-6 covers diagonal displacement.
What environment is required for ISO 230 testing?
ISO 230-1 specifies 20°C ± 2°C ambient temperature with maximum gradient of 1°C/hour. Temperature must stabilize for minimum 24 hours. Humidity should be below 75%. Vibration must be below threshold values.
What is the difference between accuracy and repeatability in ISO 230-2?
Accuracy is how close the machine positions to the commanded position (systematic error). Repeatability is how consistently it returns to the same position (random error). World-class: accuracy ±0.005mm, repeatability ±0.002mm.
How often should CNC machine accuracy be tested?
Best practice: full ISO 230-2 test annually, laser check semi-annually, and ballbar (ISO 230-4) quarterly. High-precision shops (aerospace, medical) may test monthly. Always re-test after a crash or relocation.
What is the Chinese equivalent of ISO 230?
GB/T 17421 is the Chinese national standard equivalent of ISO 230. GB/T 17421.2 corresponds to ISO 230-2 (positioning accuracy). The technical requirements are functionally identical.