ISO/TC 213/WG 14 - Vertical GPS principles

This document gives the terminology and basic concepts of association, including objective functions and association constraints and material offset. This document is not intended to specify association defaults and GPS syntax which are introduced in other (ISO GPS) International Standards. NOTE The association can be used to establish for example: — a datum; — a reference feature for a geometrical specification or for a surface texture specification; — an associated toleranced feature; — any dimensional characteristic; — an intersection plane, an orientation plane, a collection plane or a direction feature.

This document describes principles and tools to control a manufacturing process in accordance with a GPS specification. For this purpose a set of one or more complementary, independent characteristics (size, form, orientation, and location characteristics independent to each other) that correlate to the manufacturing process parameters and to the manufacturing process coordinate system established from the manufacturing datum system are used. This document describes the concept of decomposition of the macro-geometrical part of the GPS specification. It does not cover the micro-geometry, i.e. surface texture. The objective of the decomposition presented in this document is to define correction values for manufacturing control or to perform a statistical analysis of the process.

ISO 17450-4:2017 specifies general rules for quantifying GPS deviations for individual GPS characteristics. NOTE GPS deviations can be local or global. A GPS characteristic defined from local GPS deviations is a parameter that transforms the set of local deviations into a global characteristic using a quantifying function (for more details, see Table 1).

ISO 18391:2016 defines rules to establish and to indicate population specifications, which are used to specify conditions on population characteristics, which are established from a set of characteristic values obtained one on each workpiece of a population of workpieces. A population specification (as applied to a population of workpieces considered as a collection and not as individual items) can be seen as a complementary requirement to the individual specification (as applied to each workpiece considered as individual items). Population specifications express the statistical hypotheses used on the population of workpieces. NOTE 1 A population specification is a complement to an individual GPS specification. NOTE 2 ISO 18391:2016 is not intended to mandate a given tolerancing method or how to calculate tolerance values. Its intent is to specify tools to allow the expression of population specifications.

ISO 17450-3:2016 gives default definitions for the extracted features (integral or derived) of workpieces, which are toleranced features in GPS specifications (dimensional, geometrical, or surface texture specifications). This part of ISO 17450 defines default geometrical features used to define GPS characteristics.

1 Scope This part of ISO 17450 defines terms related to specifications, operators (and operations) and uncertainties used in geometrical product specifications (GPS) standards. It presents the basic tenets of the GPS philosophy while discussing the impact of uncertainty on those tenets, and examines the processes of specification and verification as they apply to GPS.

ISO 17450-1:2011 provides a model for geometrical specification and verification and defines the corresponding concepts. It also explains the mathematical basis of the concepts associated with the model and defines general terms for geometrical features of workpieces. ISO 17450-1:2011 defines the fundamental concepts for the GPS system in order to provide nonambiguous GPS language to be used in design, manufacturing and verification, to identify features, characteristics and rules to provide the basis for specifications, to provide a complete symbology language to indicate GPS specifications, to provide simplified symbology by defining default rules, and to provide consistent rules for verification.

ISO 22432:2011 defines general terms and types of features for geometrical features of specifications for workpieces. These definitions are based on concepts developed in ISO/TS 17450-1. ISO 22432:2011 is not intended for industrial use as such among designers, but is aimed to serve as the "road map" mapping out the interrelationship between geometrical features, thus enabling future standardization for industry and software makers in a consistent manner.

ISO 8015:2011 specifies fundamental concepts, principles and rules valid for the creation, interpretation and application of all other International Standards, Technical Specifications and Technical Reports concerning geometrical product specifications (GPS) and verification. It applies to the interpretation of GPS indications on all types of drawings. For the purposes of ISO 8015:2011, the term "drawing" is to be interpreted in the broadest possible sense, encompassing the total package of documentation specifying the workpiece.

ISO 25378:2011 defines general terms for geometrical specifications, characteristics and conditions. These definitions are based on concepts developed in ISO 17450-1 and ISO 22432 and they are given by using a mathematical description based on Annex B of ISO 17450-1:2011. ISO 25378:2011 is not intended for industrial use as such among designers, but is aimed to serve as the "road map" mapping out the requirements based on geometrical features, thus enabling future standardization for industry and software makers in a consistent manner. ISO 25378:2011 defines general types of geometrical characteristics and conditions which can be used in GPS. These descriptions are applicable to a workpiece, an assembly, a population of workpieces, and a population of assemblies. These definitions are based on concepts of operators and the duality principle contained in ISO 17450-1 and ISO/TS 17450-2 and on the description of types of geometrical features defined in ISO 22432. Conceptually, these specification operators can be used as specification operators or as verification operators (duality principle). ISO 25378:2011 is not intended to define GPS specifications, symbology or other types of expression.

ISO/TS 17450-1:2005 provides a model for geometrical specification and verification and defines the corresponding concepts. It also explains the mathematical basis of the concepts associated with the model.