What is GB/T 17421?
GB/T stands for "Guobiao/Tuijian" (State Standard / Recommended). GB/T 17421 is the direct Chinese adoption of the ISO 230 series.
In 95% of cases, the content is identical to ISO 230, but it's important to verify the revision year to ensure they are using the latest test methods.
Key Equivalencies
| Chinese Standard | ISO Equivalent | Subject |
|---|---|---|
| GB/T 17421.1 | ISO 230-1 | Geometric Accuracy |
| GB/T 17421.2 | ISO 230-2 | Positioning Accuracy |
| GB/T 17421.3 | ISO 230-3 | Thermal Effects |
Common Pitfalls for Importers
While the standard itself is solid, the application of the standard can vary in lower-tier factories.
1. Methodology Drift
ISO 230-2 requires 5 bi-directional runs to calculate statistical accuracy. Some reports may only show a single pass (which is more like the older JIS B 6338 standard) but label it as GB/T 17421.2.
Tip: Always ask for the raw Renishaw/API laser data files, not just the PDF summary.
2. Thermal Conditions
Standards require testing at 20°C. Many factory floors in summer can be 35°C. If the machine was tested hot without compensation, it will be undersized when it arrives in your climate-controlled shop.
Why This Matters
Understanding GB/T 17421 gives you leverage. If a manufacturer claims "0.005mm Accuracy", you can ask:"Is that according to GB/T 17421.2 with 4-sigma repeatability, or just a single max deviation?"