INTERNATIONAL STANDARD ISO 14253 1.pdf
What is ISO 14253-1 and why is it important for geometrical product specifications?
ISO 14253-1 is an international standard that establishes the rules for determining the conformity or nonconformity of a product or a measuring equipment with a given tolerance or specification, taking into account the measurement uncertainty. It is part of the ISO 14253 series of standards on geometrical product specifications (GPS), which are related to the ISO GPS matrix model.
The ISO GPS matrix model is a framework that organizes the existing and future standards on GPS into a coherent system. It consists of four fundamental concepts: size, form, orientation and location. These concepts are further divided into sub-concepts, such as diameter, flatness, parallelism and position. Each sub-concept has a corresponding standard that defines its terminology, symbols, principles, requirements and verification methods.
ISO 14253-1 applies to any sub-concept of the ISO GPS matrix model that involves a tolerance or a specification. It provides the default decision rules for verifying the conformity or nonconformity of a product or a measuring equipment with a given tolerance or specification. A decision rule is a logical procedure that specifies how to use the measured value and the measurement uncertainty to decide whether the product or the measuring equipment meets the requirement or not.
The default decision rules in ISO 14253-1 are based on the concept of conformance probability, which is the probability that a product or a measuring equipment conforms to a given tolerance or specification. The standard defines two limits for conformance probability: one for verifying conformity and one for verifying nonconformity. The default values for these limits are 95% and 5%, respectively.
The standard also specifies how to apply the decision rules in a supplier/customer relationship, where the supplier verifies the conformity of the product before delivery and the customer verifies the nonconformity of the product after receipt. The standard recommends that the supplier and the customer agree on the decision rules and the measurement uncertainty before entering into a contract.
ISO 14253-1 is important for geometrical product specifications because it ensures consistency and reliability in the verification process. It helps to avoid disputes and misunderstandings between the supplier and the customer, as well as to reduce costs and risks associated with nonconforming products or measuring equipment.
ISO 14253-1 was first published in 1998 and revised in 2013 and 2017. The latest edition incorporates some changes and clarifications, such as:
the introduction of an uncertainty zone, which is an interval around the specification limit where neither conformity nor nonconformity can be verified;
the alignment of terms and definitions with other GPS standards;
the addition of informative annexes on the relation between the third edition and the second edition, and on the relation to the GPS matrix model.
If you want to learn more about ISO 14253-1 and other GPS standards, you can visit the official website of ISO or consult some of the related standards listed below.
ISO 14638Geometrical product specifications (GPS) Masterplan
ISO/TS 17450-1Geometrical product specifications (GPS) General concepts Part 1: Model for geometrical specification and verification
ISO/TS 17450-2Geometrical product specifications (GPS) General concepts Part 2: Basic tenets, specifications, operators, uncertainties and ambiguities
ISO/IEC Guide 98-3Uncertainty of measurement Part 3: Guide to the expression of uncertainty in measurement (GUM:1995)
ISO/IEC Guide 99International vocabulary of metrology Basic and general concepts and associated terms (VIM)