BS EN ISO 21920-3:2022 pdf free download – Geometrical product specifications (GPS)一Surface texture: Profile Part 3: Specification operators.
4 Complete specification operator
4.1 Introduction
For non-explicitly specified specification elements (see Iso 21920-1) and often-used specification operators, default settings are used. Default settings should not be expected to ensure correlation with any particular workpiece function.
The advantage of the default specification operators given in 4,3 and 4A is to simplify the drawing indications.
4.2 General
The complete specification operator (see ISO 17450-2) consists of all the operators required for an unambiguous specification. It consists of an ordered full set of unambiguous specification operations in an unambiguous order. For profile surface texture, the complete specification operator defines all setting elements.
The basis for the default settings is the drawing indication according to ISO 2 1920-1. For R-parameters either the setting class or the profile L-filter nesting index shall be specified. For W-parameters either the setting class or the profile S-filter nesting index shall be specified.
For the R-parameters Ra, Rq, Rz, Rp, Rv, Rzx and Rt, and for Pt, all default settings can be specified by the specification of the tolerance limit, see 4.43 to 4.46.
A flowchart illustrating the general way to determine the specification operators is given in Annex A. Examples for the determination of default settings are given in Annex 13. Annex C provides an overview of the most important changes in the determination of the default settings according to this document in relation to ISO 4288. A recommendation for the selection of settings in the absence of a specification is given in Annex D. Annex E provides an overview of the profile and areal standards in the GPS matrix model.
NOTE 1 There is no distinction between periodic and non-periodic profiles.
NOTE 2 This document describes specification operators. For the verification, the following applies: “the verification operator is the physical implementation of the specification operator. It may have exactly the same operations in the same order, in which case the method uncertainty is zero, or it may have different operations or perform the operations in a different order, in which case the method uncertainty is not zero.” [SOURCE: ISO 8015:2011, 5.10.1]
NOTE 3 There are no defaults for electromagnetic profiles.
F.1 General
The ISO GPS matrix model given in Iso 14638 gives an overview of the ISO GPS system of which this document is a part.
The fundamental rules of ISO GPS given in ISO 8015 apply to this document and the default decision rules given in ISO 14253-1 apply to specifications made in accordance with this document, unless otherwise indicated.
F.2 Information about this document and its use
This document specifies the complete specification operator for surface texture by profile methods.
F.3 Position in the GPS matrix model
This document is a general ISO GPS standard which influences chain link C of the chains of standards on profile surface texture in the GPS matrix model as shown in Table F.1. The rules and principles given in this document apply to all segments of the ISO GPS matrix which are indicated with a filled dot (.).