Iso 14253 1.pdf [top] | International Standard

ISO 14253-1:2017 establishes standardized decision rules for verifying the conformity or nonconformity of workpieces and measuring equipment with specifications, incorporating measurement uncertainty. It defines acceptance and rejection zones based on a default 95% confidence level, reducing disputes by clearly addressing borderline measurements. For detailed information, visit ISO.

2. Key Concepts

2.1 Specification limits

• Upper specification limit (USL)
• Lower specification limit (LSL)

1. Improved measurement accuracy: By following standardized measurement procedures, measuring equipment users can ensure that their measurements are accurate and reliable.
2. Increased efficiency: The standard helps to reduce the time and effort required for measurement and inspection, leading to increased productivity.
3. Enhanced global trade: By using standardized measurement procedures, companies can facilitate global trade and collaboration, reducing the risk of measurement-related disputes.

• Conformance zone: (y + U \le \textUSL) and (y - U \ge \textLSL) (unambiguous pass)
• Non‑conformance zone: (y - U \ge \textUSL) or (y + U \le \textLSL) (unambiguous fail)
• Indeterminate zone (upper): (\textUSL - U < y < \textUSL + U) but (y) not clearly in fail zone
• Indeterminate zone (lower): similar near LSL

Zone 2: Non-Conformance Zone

• Condition: The measurement result ($y$) minus the uncertainty ($U$) is greater than the upper limit, OR the result plus the uncertainty is less than the lower limit.

  According to ISO 14253-1: