Draft for Public Comment
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Latest date for receipt of comments: 30 November 2011
Project No. 2010/01936
Responsible committee: TDW/4 Technical Product Realization Interested committees:
Title:: Title
Draft BS EN ISO 1938-1 Geome Geometrica tricall product product speci specificat fications ions (GPS) - Dimensio Dimensional nal measu measuring ring equip equipment ment Part 1: Plain limit gauges of linear size
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ONLY EXAMPLE 3.1
Definition 1
ed
Definition is ambiguous and needs clarifying. Amend to read '...so that the mains connector to which no connection. connection...' ..'
6.4
Paragraph 2
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The use of the UV photometer as an alternative cannot be supported as
serious problems have been encountered in its use in the UK.
Delete reference to UV photometer.
EUROPEAN STANDARD NORME EUROPÉENNE
DRAFT prEN ISO 1938-1
EUROPÄISCHE NORM August 2011 ICS 17.040.10
English Version
Geometrical product specifications (GPS) - Dimensional measuring equipment - Part 1: Plain limit gauges of linear size (ISO/DIS 1938-1:2011) Spécification géométrique des produits (GPS) Equipement de mesure dimensionnel - Partie 1: Calibres lisses à limite de taille linéaire (ISO/DIS 1938-1:2011)
Geometrische Produktspezifikation Produktspezifikation (GPS) - Maßtolerierung - Teil 1: Grenzlehren und Lehrung der Längenmaße (ISO/DIS 1938-1:2011)
This draft European Standard is submitted to CEN members f or parallel enquiry. It has been drawn up by the Technical Committee CEN/TC 290. If this draft becomes a European Standard, CEN members are bound to comply with the CEN/CENELEC Internal Regulations which stipulate the conditions for giving this European Standard the status of a national standard without any alteration. This draft European Standard was established by CEN in three official versions (English, French, German). A version in any other language made by translation under the responsibility of a CEN member into its own language and notified to the CEN-CENELEC Management Centre has the same status as t he official versions. CEN members are the national standards bodies of Austria, Belgium, Bulgaria, Croatia, Cyprus, Czech Republic, Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland and United Kingdom. Recipients of this draft are invited to submit, with their comm ents, notification of any relevant patent rights of which they are aware and to provide supporting documentation. Warning : This document is not a European Standard. It is distributed for review and comments. It is subject to change without notice and
shall not be referred to as a European Standard.
EUROPEAN COMMITTEE FOR STANDARDIZATION COMITÉ EUROPÉEN DE NORMALISATION EUROPÄISCHES KOMITEE FÜR NORMUNG
Management Centre: Avenu Avenue e Marnix 17, 17, B-1000 Brussels Brussels
© 2011 CEN
All rights rights of exploitation in any form and by any any means reserved worldwide for CEN national Members.
Ref. No. prEN ISO 1938-1:2011: E
prEN ISO 1938-1:2011 (E)
Contents
Page
Foreword ....................................................................................................... ..............................................................................................................................................................3 .......................................................3
prEN ISO 1938-1:2011 (E)
Foreword This document (prEN ISO 1938-1:2011) has been prepared by Technical Committee ISO/TC 213 "Dimensional and geometrical product specifications and verification" in collaboration with Technical Committee CEN/TC 290 “Dimensional and geometrical product specification and verification” the secretariat of which is held by AFNOR. This document is currently submitted to the parallel Enquiry.
Endorsement notice The text of ISO/DIS 1938-1:2011 has been appro ved by CEN as a prEN ISO 1938-1:2011 without any modification.
DRAFT INTER INTERNATIO NATIONAL NAL STAND STANDARD ARD ISO/DIS 1938-1 ISO/TC 213
Secretariat: DS
Voting begins on 2011-08-18
Voting terminates on 2012-01-18
INTERNATIONAL ORGANIZATION FOR STANDARDIZATION
МЕЖДУНАРОДНАЯ ОРГАНИЗАЦИЯ ПО СТАНДАРТИЗАЦИИ
ORGANISATION INTERNATIONALE DE NORMALISATION
Geometric al pro duct specific ations (G Geometric (GPS PS)) — Dimensio Dimensional nal measuri mea suri ng equip ment —
Part 1: Plain Pla in limit l imit gauges of li nea nearr size si ze Spécification géométrique des produits (GPS) — Équipement de mesure dimensionnel — Partie 1: Calibres lisses à limite de taille linéaire
[Revision of first edition (ISO/R 1938-1:1971)]
ICS 17.040.10
This draft has been developed within the International Organization for Standardization (ISO), and processed under the ISO-lead ISO-lead mode mode of collaboration as defined in the Vienna Agreement. This draft is hereby submitted to the ISO member bodies and to the CEN member bodies for a parallel five-month enquiry. Should this draft be accepted, a final draft, established on the basis of comments received, will be submitted to a parallel two-month approval vote in ISO and formal vote in CEN.
To expedite distribution, this document is circulated as received from the committee secretariat. secre tariat. ISO ISO Central Central Secretaria Secretariatt w ork o f editing and text comp osition will be undertaken at publication stage. Pour accélérer la distribution, le présent document est distribué tel qu'il est parvenu du secrétariat du comité. Le travail de rédaction et de composition de texte sera effectué au Secrétariat central de l'ISO au stade de publication.
THIS DOCUMENT IS A DRAFT CIRCULATED FOR COMMENT AND APPROVAL. IT IS THEREFORE SUBJECT TO CHANGE AND MAY NOT BE REFERRED TO AS AN INTERNATIONAL STANDARD UNTIL PUBLISHED AS SUCH. IN ADDITION TO THEIR EVALUATION AS BEING ACCEPTABLE FOR INDUSTRIAL, TECHNOLOGICAL, COMMERCIAL AND USER PURPOSES, DRAFT INTERNATIONAL STANDARDS MAY ON OCCASION HAVE TO BE CONSIDERED IN THE LIGHT OF THEIR POTENTIAL TO BECOME STANDARDS TO WHICH REFERENCE MAY BE MADE IN NATIONAL REGULATIONS. RECIPIENTS OF THIS DRAFT ARE INVITED TO SUBMIT, WITH THEIR COMMENTS, NOTIFICATION OF ANY RELEVANT PATENT RIGHTS OF WHICH THEY ARE AWARE AND TO PROVIDE SUPPORTING DOCUMENTATION.
ISO/DIS 1938-1
Copyright Co pyright notice This ISO document is a Draft International Standard and is copyright-protected by ISO. Except as permitted under the applicable laws of the user’s country, neither this ISO draft nor any extract from it may be reproduced, stored in a retrieval system or transmitted in any form or by any means, electronic, photocopying, recording or otherwise, without prior written permission being secured. Requests for permission to reproduce should be addressed to either ISO at the address below or ISO’s member body in the country of the requester. ISO copyright office Case postale 56 CH-1211 Geneva 20 Tel. + 41 22 749 01 11 Fax + 41 22 749 09 47 E-mail
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Reproduction may be subject to royalty payments or a licensing agreement. Violators may be prosecuted.
ISO/DIS 1938-1
Contents Foreword.....................................................................................................................................................................iv Introduction.................................................................................................................................................................v 1
Scope ..................................................................................... ....................................................................................................................................................... ......................................................................... ....... 1
2
Normative references............................................................................................................ references.................................................................................................................................... ........................ 1
3 3.1 3.2 3.3
Terms and definitions definitions and abbreviations abbreviations ........................................................................................ ................................................................................................... ........... 2 Limits ....................................................................................... ....................................................................................................................................................... ....................................................................... ....... 2 Gauge types ............................................................................... ...................................................................................................................................................3 ....................................................................3 Characteristics Characteristics and function of gauges ........................................................................................... ...................................................................................................... ........... 6
4
Abbreviations.................................................................................................................................................8
5
Design characteristics characteristics for gauges .......................................................................................... ...............................................................................................................8 .....................8
6 6.1 6.2
Metrological Metrological characteristics .................................................................................... .......................................................................................................................10 ...................................10 General..........................................................................................................................................................10 Metrological Metrological characteristic relative relative to the type of limit gauge (GO gauge or NOT GO gauge) ........... 10
7 7.1 7.2 7.3
Maximum permissible permissible limits on metrological characteristics ................................................................15 General..........................................................................................................................................................15 Limit gauges for internal features features of size .................................................................................. .................................................................................................15 ...............15 Limit gauges for external features of size.......................................................................................... size................................................................................................. ....... 17
8
Proving conformance conformance with specification specification for limit gauges ......................................................................21
9
General principles of gauging.................................................................................................................... gauging.................................................................................................................. ..24 24
10
Marking ........................................................................................... .........................................................................................................................................................24 ..............................................................24
Annex A (informative) General application of limit gauging.................................................................................25 Annex B (informative) Description Descriptio n of the specific use of the various gauge types and the associated uncertainty .......................................................................................... ...................................................................................................................................................26 .........................................................26 Annex C (informative) Relation to the GPS matrix model.....................................................................................28 Bibliography..............................................................................................................................................................30
ISO/DIS 1938-1
Foreword ISO (the International Organization for Standardization) is a worldwide federation of national standards bodies (ISO member bodies). The work of preparing International Standards is normally carried out through ISO technical committees. Each member body interested in a subject for which a technical committee has been established has the right to be represented on that committee. International organizations, governmental and non-governmental, in liaison with ISO, also take part in the work. ISO collaborates closely with the International Electrotechnical Commission (IEC) on all matters of electrotechnical standardization. International Standards are drafted in accordance with the rules given in the ISO/IEC Directives, Part 2. The main task of technical committees is to prepare International Standards. Draft International Standards adopted by the technical committees are circulated to the member bodies for voting. Publication as an International Standard requires approval by at least 75 % of the member bodies casting a vote. Attention is drawn to the possibility th at some of the elements of this document may be the subject of patent rights. ISO shall not be held responsible for identifying any or all such patent rights. ISO 1938-1 was prepared by Technical Committee ISO/TC 213, Geometrical product specifications and verification. verification. This standard cancels and replaces ISO/R 1938:1971, which has been technically revised. ISO 1938 consists of the following parts, un der the general ge neral title Geometrical Geometrical product specifications (GPS) — Dimensional measuring equipment : ⎯
Part 1: Plain limit gauges of linear size
⎯
Part 2: Reference disc gauges
This edition of ISO 1938 do not include requirements for setting plug gauges and setting ring gauges, which was dealt with in clause 3.9.4 in ISO/R 1938:1971.
ISO/DIS 1938-1
Introduction This International Standard is a geometrical product specification (GPS) standard and is to be regarded as a general GPS standard (see ISO/TR 14638). It influences link 4, 5 of the size chain of standards in the general GPS matrix. For more detailed information of the relation of this standard to other standards and the GPS matrix model see Annex C. The ISO/GPS Masterplan given in ISO/TR 14638 gives an overview of the ISO/GPS system of which this standard is a part. The fundamental rules of ISO/GPS given in ISO 8015 apply to this standard and the default decision rules given in ISO 14253-1 apply to specifications made in accordance with this standard, unless otherwise indicated The terms and concepts used in this edition of ISO 1938 (compared to the former edition ISO/R 1938:1971) are changed according to needs and terminology in the other GPS standards. This International Standard deals with plain limit gauges intended for proving conformance with linear sizes for features of size when the dimensional specification are required (see ISO 14405-1), for rigid workpieces.
ISO/DIS 1938-1
Geometrical Geometri cal produc pro ductt specifi sp ecification cations s (GPS (GPS)) — Dimension Dimensional al measuring equipment — Part 1: Plain Pla in limi l imitt gauges of li nea nearr size si ze 1
Scope
This International Standard specifies the most important metrological and design characteristics of plain limit gauges of linear size This International Standard defines the different types of plain limit gauges used to prove conformance with linear dimensional specification associated to linear size. This International Standard also defines the design characteristics and the metrological characteristics for these limit gauges as well as the new or wear limits state Maximum Permissible Errors (MPEs) for these characteristics. This International Standard also describes the use of limit gauges and it covers linear sizes up to 500 mm.
2
Normative references
The following normative documents contain provisions which, through reference in this text, constitute provisions of this International Standard. For dated references, subsequent amendments to, or revisions of, any of these publications do not apply. However, parties to agreements based on this International Standard are encouraged to investigate the possibility of applying the most recent editions of the normative documents indicated below. For undated references, the latest edition of the normative document referred to applies. Members of ISO and IEC maintain registers of currently valid International Standards. ISO 1:2002, Geometrical product specifications (GPS) — Standard reference temperature for geometrical product specifications and verification ISO 286-1:2010, Geometrical Geometrical product specification (GPS) — ISO code system for tolerances of linear sizes — Part 1: basis of tolerances, deviations and fits ISO 1101:2004, Geometrical product specifications (GPS) — Geometrical tolerancing — Tolerancing of form, orientation, location and run-out ISO 14405-1:2010, Geometrical Product Specification (GPS) — Dimensional tolerancing — Part 1: linear sizes ISO 14253-1:1998, Geometrical Product Specifications (GPS) — Inspection by measurement of workpieces and measuring equipment — Part 1: Decision rules for proving conformance or non-conformance with specifications ISO 14660-1:1999, 14660-1:1999, Geometrical Product Specifications (GPS) — Geometrical features — Part 1: General terms and definitions ISO 14978:2006, Geometrical product specifications (GPS) — General concepts and requirements for GPS measuring equipment ISO 17450-1:— 17450-1:—1) Geometrical Product Specification Specifica tion (GPS) — General concepts — Part 1: model for geometrical specification and verification
1)
To be published
ISO/DIS 1938-1
ISO 17450-2:— 17450-2:—2) Geometrical product specifications specific ations (GPS) — General concepts — Part 2: Basic tenets, specifications, operators and uncertainties uncertainties ISO/IEC Guide 98-3:2008, Uncertainty of measurement — Part 3: Guide to the expression of uncertainty in measurement (GUM:1995) measurement (GUM:1995) ISO/IEC Guide 99:2007, International vocabulary of metrology — Basic and general concepts and associated terms (VIM)
3
Terms and definitions and abbreviations
For the purpose of this International Standard, the terms and definitions d efinitions given in ISO 14660-1, ISO 286-1, ISO 14405-1, ISO 17450-2, ISO/IEC Guide 98-3 and ISO/IEC Guide 99 and the following definitions apply.
3.1 Limits 3.1.1 maximum material limit of size MMLS limit of size corresponding to the maximum material condition of feature of size NOTE 1
MMLS includes the numerical value for the size and the specified specified association association criteria. criteria.
NOTE 2
A number of different association criteria criteria for size are given in ISO 14660-2 and ISO 14405-1.
3.1.2 least material limit of size LMLS limit of size corresponding to the least material condition of feature of size NOTE 1
LMLS includes the numerical value for the size and the specified association criteria.
NOTE 2
A number of different association criteria criteria for size are given in ISO 14660-2 and ISO 14405-1.
3.1.3 upper limit of size ULS largest permissible size of a feature of size [ISO 286-1:2010, 3.2.3.1] NOTE
ULS is a numerical value.
3.1.4 lower limit of size LLS smallest permissible size of a feature of size [ISO 286-1:2010, 3.2.3.2] NOTE
2)
LLS is a numerical value.
To be published
ISO/DIS 1938-1
3.1.5 upper specification limit (of the gauge) USL limit of a specification for a metrological characteristic of a gauge having the largest value 3.1.6 lower specification limit (of the gauge) LSL limit of a specification for a metrological characteristic of a gauge having the smallest value
3.2 Gauge types 3.2.1 limit gauge gauge designed and intended to verify only if workpiece characteristics are inside or outside the tolerance at one of its tolerance limits. NOTE 1 When a limit gauge is designed to verify an internal feature of of size (an hole for example), then it can be called internal limit gauge. NOTE 2 When a limit gauge is designed to verify an external feature of size (a shaft for example), then it can be called external limit gauge. NOTE 3
General application of limit gauge is given in Annex A.
3.2.2 plain limit gauge limit gauge with only one or two gauge elements, each one simulating a perfect feature of size, whose the size is derived from upper or lower specification limits of the size of a feature of size NOTE 1 When a plain limit gauge consists of only one element, it is qualified qualified as simple (simple plain limit gauge: GO plain limit gauge or NOT GO plain limit gauge). NOTE 2 GO).
When a plain limit gauge consists of two elements, it is qualified as double (double plain limit gauge: GO and NOT
3.2.3 full form cylindrical plug gauge (Gauge type A) plain limit gauge designed to simulate a cylinder as a contacting feature with an internal cylinder See Table 1. NOTE The GO gauge type A simulates the maximum material limit of size attached with the envelop requirement apply to a dimensional specification on the workpiece when the length of the gauge exceed the length of the feature of size of the workpiece.
3.2.4 segmental cylindrical bar gauge (Gauge type B) plain limit gauge designed to simulate two opposite angular portions of a cylinder as a contacting feature with a internal cylinder See Table 1. 3.2.5 segmental cylindrical bar gauge with reduced gauging surfaces (Gauge type C) segmental cylindrical bar gauge designed to simulate two reduced opposite angular portions of a cylinder as a contacting surface with an internal cylinder See Table 1.
ISO/DIS 1938-1
3.2.6 full form spherical plug gauge (Gauge type D) disc gauge plain limit gauge designed to simulate a circle as a contacting feature with an internal cylinder See Table 1. NOTE
The shape shape of this gauge type is not spherical, but a torus - but per tradition the name is “spherical plug gauge”.
3.2.7 segmental spherical plug gauge (Gauge type E) plain limit gauge designed to simulate two opposite angular portions of a circle as a contacting feature with an internal cylinder See Table 1. NOTE gauge”.
The shape of this this gauge type is not spherical but a torus - per tradition the name is “segmental spherical plug
3.2.8 bar gauge (full form bar gauge) (Gauge type F) plain limit gauge designed to simulate two opposite planes as a contacting feature with an internal feature of size consisting of two opposite planes See Table 1. 3.2.9 rod gauge with spherical ends (Gauge type G) Plain limit gauge designed to simulate two opposite points as a contacting feature with a internal feature of size consisting of two opposite planes or of a cylinder See Table 1. NOTE The active part of a rod gauge with with spherical ends ends consists only of two points: The two points at the largest distance between the two spheres.
ISO/DIS 1938-1
Table 1 —Types of limit gauge for internal feature of size Limit gauge
Type
Illustration
Contacting feature with feature of size of "type Cylinder"
Contacting feature with feature of size of type "two opposites planes"
Full form cylindrical plug gauge
Gauge type A
Cylinder
Two opposite straight lines
Segmental cylindrical bar gauge
Gauge type B
Two opposite angular portions of cylinder
Two opposite straight lines
Segmental cylindrical bar gauge with reduced gauging surfaces
Gauge type C
Two opposite angular reduced portions of cylinder
Two opposite line segments
Full form spherical plug gauge
Gauge type D
Circle
Two points
Segmental spherical plug gauge
Gauge type E
Two opposite angular portions of circle
Two points
Bar gauge
Gauge type F
Rod gauge with spherical ends
Gauge type G
Two opposite planes
Two points
Two points
ISO/DIS 1938-1
3.2.10 full form cylindrical ring gauge (Gauge type H) plain limit gauge designed to simulate a cylinder as contacting feature with an external cylinder See Table 2. 3.2.11 full form notch gauge (Gauge type J) plain limit gauge designed to simulate straight lines or flat surfaces on two opposite parallel planes as contacting features with an external feature of size consisting of a cylinder or two opposite planes See Table 2. 3.2.12 gap gauge (Gauge type K) Plain limit gauge designed to simulate portions (straight lines or flat surfaces) on two opposite planes as contacting feature with an external feature of size consisting of two opposite planes See Table 2. Table 2 —Types of limit gauge for external feature of size Limit gauge
Type
Illustration
Contacting feature with feature of size of type: "cylinder" " two opposites planes" Cylinder
Full form cylindrical ring gauge
Gauge type H
Full form notch gauge
Gauge type J
Two opposite straight lines
Two opposite planes
Gap gauge
Gauge type K
Two opposite segments
Two opposite portions of planes
3.3 Characteristics Characteristics and function of gauges 3.3.1 non adjustable gauge gauge with an inherent, stable and not changeable metrological characteristic. NOTE EXAMPLE
The metrological characteristics of a fixed gauge may change with e.g. temperature and wear. A full form cylindrical plug gauge and a full form cylindrical ring gauge are non adjustable gauges.
3.3.2 adjustable gauge Gauge designed in a way that the inherent metrological characteristic can be intentionally changed by the user.
ISO/DIS 1938-1
NOTE EXAMPLE
The metrological characteristics of a adjustable gauge may also change with e.g. temperature and wear. A variable gap gauge and a variable rod gauge with spherical ends are adjustable gauges.
3.3.3 GO gauge gauge designed to verify the size of the workpiece relative to maximum material limit of the size tolerance according to the dimensional specification NOTE Usually relatively to the MMLS of the dimensional specification, the GO gauge shall pass over the actual feature of size of the workpiece to prove the conformance and the NO GO gauge shall not pass over the actual feature of size of the workpiece to prove the non-conformance.
3.3.4 NO GO gauge gauge designed to verify the size of the workpiece relative to least material limit of the size tolerance according to the dimensional specification NOTE Usually relatively to the least material limit of size (LMLS) of the dimensional specification, the NO GO gauge should not pass over the actual feature of size of the workpiece to prove the conformance conformance and the NO GO gauge gauge should pass over the actual feature of size of the workpiece to prove the non-conformance.
3.3.5 length of gauge element LG active length of a gauge in the direction perpendicular to a cross section of the gauged feature of size NOTE For a cylindrical gauge element it is the length of the cylinder (see Table 4). For a gauge element of type two parallel opposite surfaces it is the length of the bar or notch (see Table 4). For a gap gauge it is the width of the anvils (see Table 4).
3.3.6 width of gauge element HG active width of a gauge in the direction parallel to a cross section of the gauged feature of size NOTE For a gauge element of of type two two parallel parallel opposite surfaces it is the the height of the bar or notch (see Table 4). For a gap gauge it is the height of the anvils (see Table 4).
3.3.7 new state specification (of a limit gauge) specification for metrological characteristics of a new gauge to be used by a manufacturer or supplier 3.3.8 wear limits state specification (of a limit gauge) specification for metrological characteristics of a used gauge to be used to verify conformance or non-conformance with the workpiece specification operator NOTE 1
The user may use standardized wear wear limits state specifications, e.g. as given in this standard.
NOTE 2
The wear wear limits state specifications consider the gauge as used, and can include wear wear limits.
3.3.9 new state permissible errors of a metrological characteristic permissible errors of a metrological characteristic in a new state specification 3.3.10 wear limits state permissible errors of a metrological characteristic permissible errors of a metrological characteristic in a wear limits state specification
ISO/DIS 1938-1
4
Abbreviations
For the purpose of this standard, the abbreviations given in Table 3 apply. Table 3 — Abbreviations Abbreviation B F GO H HG USL LG LSL LMLS M MMLS MPE MPL NO GO S SR T U W y y1 z z1 α α
1
5
Description width of segmental gauge element tolerance value of form specification on limit gauge go gauge interval tolerance on the size characteristic, S, of new state gauge width of gauge element upper specification limit (of a gauge) length of gauge element lower specification limit (of a gauge) least material limit of size new state gauge maximum material limit of size maximum permissible error maximum permissible limits of a metrological characteristic no go gauge size spherical radius of the gauge tolerance wear limits state gauge workpiece amount outside of workpiece tolerance limit taking into account a margin of wear limit force internal feature of size amount outside of workpiece tolerance limit taking into account a margin of wear limit force external feature of size Distance between centre of tolerance for GO new state gauge and the lower specification limit of an internal feature of size of a workpiece Distance between centre of tolerance for GO new state gauge and the upper specification limit of an external feature of size of a workpiece safety value for compensation of measurement uncertainty for internal feature of size safety value for compensation of measurement uncertainty for external feature of size
Design characteristics for gauges
The material used for gauges shall be suitably selected with due consideration to its size stability, durability and stiffness. Gauging elements shall normally be manufactured from an high quality steel suitably selected to provide a high degree of wear resistance after heat treatment. Other wear-resistant materials, e.g. tungsten carbide, may be used provided that their wear qualities are not less than those of the steel specified above. NOTE
The temperature expansion coefficient of the material used is to be considered together with the wear resistance.
Hard plating or other surface treatments in order to improve the wear resistance of the surface may also be applied to gauging surfaces, but the thickness of deposit shall at least be of an amount, that an acceptable gauge always has a fully intact layer of wear resistant material. The hardness of the gauging surface shall not be less than 670 HV 30 (approximately 58 HRC), irrespective of the type of material. There may be specific applications where the use of special materials (e. g. aluminium and glass) is required by the nature of the workpiece or the manufacturing environment. In such cases it may not be possible to have the required hardness or wear resistance.
ISO/DIS 1938-1
The gauging surface shall be finished by fine grinding or lapping or a process which results in a smooth type of surface. The surface roughness of gauging surface face shall be specified and the Ra value shall not exceed 10 % of the new state gauge MPL for size (see Table 7) with a upper limit value of 0,2 µm, and cut-off value of 0,8 mm. Other surface texture parameter could be specified in addition. All sharp edges shall be removed unless functionally required. The characteristics associated to the grip/handle of the gauge are also design characteristics. Design options on some gauges are possible and are given below: ⎯
air slot: for GO gauge- full form cylindrical plug gauge : this option is intended to verify a blind hole, to avoid phenomena of compression and suction. This option requires defining dimensions of the air slot.
⎯
precentering/pilot (see Figure 1): for GO gauge or NOT GO gauge - full form cylindrical plug gauge and segmental cylindrical bar gauge: this option is intended to facilitate the introduction of the gauge in the workpiece. This option requires defining dimensions of precentering or pilot.
Figure 1 – Illustration of precentering precentering option ⎯
material relief (see Figure Figure 2): For GO gauge- full form cylindrical plug gauge These options allow to detect a potential oval deformation of hole. This option requires defining attached dimensions.
Figure 2 – Illustration of material relief option Other specific design characteristics, attached to a type of gauge, are described in Tables 4 and 5.
ISO/DIS 1938-1
6
Metrological characteristics
6.1 General A plain limit gauge manages one or two gauge elements (GO gauge or NOT GO gauge or go and NOT GO gauge). On each gauge feature are defined metrological characteristics. The metrological characteristic impacts on the quality of the result of evaluation made by using a plain limit gauge. The most important metrological characteristic is its size S, and form characteristics relative to the measuring feature of the plain gauge. To define the metrological characteristic on a plain gauge, the modifiers defined in ISO 14405-1 and the symbol defined in ISO 1101 are used. The size can be seen metrologically by different ways for example, on a cylinder, it is possible to evaluate the maximum inscribed diameter, the minimum circumscribed diameter, the minimum local diameter, the maximum local diameter, the least square diameter. Each of them can give different result of measurement. For this reason the metrological characteristic includes this information (by adding after the size a modifier as defined in ISO 14405-1). Depending to the use of the plain gauge and its type, the metrological characteristic impacting the uncertainty of verification can be different, for a same plain gauge. EXAMPLE For a full form cylindrical plug gauge (gauge type A) used to verify the lower limit of size linked to a dimensional specification apply on a cylindrical hole with envelop requirement, the size to be considered is the minimum circumscribed diameter on the GO gauge (S ) . For the same full form form cylindrical plug gauge (gauge type type A) use to verify the lower lower limit of size linked to a dimensional specification applied on a slot without envelop requirement, the size to be considered is the two ). points diameter on the GO gauge (S NOTE When a slot without envelope requirement is checked for its lower limit with a gauge type A, two parallel lines will be checked which do not exactly correspond to the definition for two-point size. The gauge type G is the gauge type that follows the definition for two-point size. "
This International standard describes potential metrological characteristics available on plain limit gauge. The final decision to select one or several metrological characteristics is left to the user.
6.2 Metrological characteristic characteristic relative to the type of limit gauge (GO gauge or NOT GO gauge) Tables 4 and 5 give potential metrological characteristics associated to a type of gauge type, but also complementary design characteristics as defined in Clause 5. Depending on the need of the user, a set of these metrological characteristics shall be defined; by default the two point size is required for the size, S, of the gauge limit and the form deviation also.
ISO/DIS 1938-1
Table 4 — List of potential design and metrological characteristics for external gauge type Description
Complementary design characteristics
Full form cylindrical plug gauge - Gauge type A
LG
Fc
Metrological characteristics for GO gauge
Metrological characteristics for NOT GO gauge
S
S
/0
S
S
/0
S
a
a
S S ø
⌭ * ⃝ LG
⃝
Segmental cylindrical bar gauge - Gauge type B
LG Fc
B
S CT
S CT
/0
S CT
S CT
/0
S CT
a
a
S CT
⌭ CZ a
S ø
⃝
⃝ CZ
B
LG
Segmental cylindrical bar gauge with reduced gauging surfaces - Gauge type C
LG
S CT
S CT
/0
S CT
S CT
/0
S CT
*
Fc
B
S CT LT : total length
*
⌭ CZ a
S ø
⃝ CZ
B
LG
⃝ CZ
ISO/DIS 1938-1
Table 4 (continued) Description
Complementary design characteristics
Full form spherical plug gauge - Gauge type D
R Fh Fh
LT
Metrological characteristics for GO gauge
Metrological characteristics for NOT GO gauge
S
/0
S
/0
S
/0
S
/0
S
a
a
S
⃝
⃝*
S ø
LG~ 0
~
R
Segmental spherical plug gauge - Gauge type E
S
Fh Fh
B
S CT
/0
S CT
/0
S CT
/0
S CT
/0
a
S CT ⃝ CZ*
LT
a
S CT ⃝ CZ
S ø
LG~ 0
~
R
B
Bar gauge - Gauge type F
LG Fb A
B
S
S
/0
S
S
/0
S
HG
A
Fb B
a
S
a
S
Parallelism between the faces
Parallelism between the faces
Fb* A
Fb
and
and
A
G L
of
of HG
surface A
surface A
ISO/DIS 1938-1
Table 4 (end) Description
Complementary design characteristics
Rod gauge with spherical ends - Gauge type G
RS
Metrological characteristics for GO gauge
S CT
a
Form a of spheres without taking into account the size of the sphere
a
default metrological characteristics to be considered
GX maximum inscribed GN
minimum circumscribed
CC circumferential LP
two points size
Metrological characteristics for NOT GO gauge S CT
a
Form of Spheres without taking into account the size of the sphere
ISO/DIS 1938-1
Table 5 — List of potential design and metrological characteristics characteristics for internal gauge type Description
Complementary design characteristics
Full form cylindrical ring gauge : Gauge type H
Dy
Metrological characteristics for GO gauge
Metrological characteristics for NOT GO gauge
S
S
/0
S
S
/0
øDy
LG
a
S
⌭
a
S
a ⃝
⃝
G L
Fr
øS
Full form notch gauge - Gauge type J
LG
Fb A
HG
B
S
S
S
S
S
*
S
A
S
*
Fb B
Fg A
a
Fg A
a
and
and G L
of surface A of surface A HG
Gap gauge - Gauge type K Fg B
LG
S
S
S
S
HG
B
*
S
Fg A
A
Fg A
A
a
and A-A
of surface A G H
A US
LG
Remove the line of section A-A see 128-1 Constraint condition : a) normally the dimension HG is vertical compared to the gravity direction b) gap gauges shall used for rigid work pieces onl y a
default metrological characteristics to be considered
*
S
Fg A
a
and
of surface A
ISO/DIS 1938-1
7
Maximum permissible limits on metrological characteristics
7.1 General The maximum permissible limits for a gauge are completely equivalent to the specification limits on a characteristic. a)
The maximum maximum permissible limits on form and orientation characteristic are asymmetrical:
⎯
the upper limit of MPL on these characteristic is equal to the value of F given in Table 6 and depending to the type of the gauge.
⎯
the lower limit of MPL on these characteristic is equal to 0.
The evaluation of these characteristic shall be in accordance to ISO 1101 and shall fulfil in MPLs. EXAMPLE
A metrological characteristic of cylindricity with its MPEs is equivalent to the follow requirement:
. Its meaning is given in ISO 1101. b)
Specifications for metrological characteristics associated to S to a limit gauge of the same type used as a GO gauge and as a NO GO gauge are different (see 7.2 and 7.3).
Specifications for new or wear limits state attached to the metrological characteristics associated to S to limit gauges are always different for GO gauges and may be equal for NO GO gauges. The new state specification limits of GO gauges are always positioned inside the workpiece tolerance When the tolerance of the dimension of feature of size of workpiece is given as a code according to ISO 2861:2010 Tables 7 to 11 can be used directly. When the size tolerance is not given as an ISO code, the standard tolerance grade shall be defined as the standard tolerance grade corresponding to the first tolerance interval, T, given in Tables 7 to 11, lower than to the tolerance interval of the workpiece in the same range of nominal sizes. EXAMPLE For a dimensional specification given on the workpiece, by 20 ± 0, 02 Ⓔ, the tolerance interval on the workpiece is equal to 40 µm. In Table 8, in the nominal range where 20 is included, the lower standardised tolerance interval is equal to 33 µm, corresponding to the standard tolerance grade equal to 8, which is to be used to define the metrological characteristic for a plain limit gauge to verify this dimensional specification. NOTE For GO gauges its specification limits are positioned by z and z1 relative to the tolerance limit of the workpiece (Figure 3 and Figure 4) in order to allow a certain wear and therefore a certain time in use before the size and form is worn outside the specification for the limit gauge.
7.2 Limit gauges for internal features of size The positions of new state tolerance limits, and wear limits for limit gauges for internal features of size in relation to workpiece tolerance limits are shown in Figure 3. The NO GO gauge specification is positioned relative to the LMLS of the workpiece tolerance. The GO gauge specification is positioned relative to the MMLS of the workpiece tolerance.
ISO/DIS 1938-1
H/2 USL= LMLS
NO GO
H α
H
NO
H/2
GO
H/2 GO
H
GO
H
z α
LSL = MMLS
y
y
Tolerance
on
workpiece
Lower Wear limit
Nominal size up to and
Nominal size above 180
included to 180 mm
mm
Figure 3 – MPL size position for GO and NO GO gauges for workpieces workpieces of internal feature of size The value for H (see Figure 3) is specific for each type of limit gauge, workpiece tolerance grade and workpiece feature size and shall be taken from Table 6. The values of z, α and y (see Figure 3) is specific for each workpiece tolerance grade and workpiece feature size, and shall be taken from Table 8. When a plug gauge is to be used as a not go limit gauge (for LMLS) of a workpiece feature (LMLS(WP)) the requirement on the size, S, of the gauge element is : ⎯
The tolerances of gauge for new and wear limits state are (see Figure 3): ⎯
for upper specification limit:
USL(U)NO GO =USL(M)NO GO =USL(W) - α + H/2
⎯
for lower specification limit:
LSL(U)NO GO = LSL(M)NO GO =USL(W) - α - H/2
NOTE
α is
equal to zero when the nominal value is up to or equal to 180 mm.
When a plug gauge is to be used as a new GO gauge (for MMLS) of a workpiece feature (MMLS (WP)), the requirement on the size, S, of the gauge element is: ⎯
⎯
The tolerances of gauge for new state are (see Figure 3): ⎯
for the upper specification limit:
USL(M)GO = LSL(W) + z + H/2
⎯
lower specification limit: (LSL):
LSL(M)GO = LSL(W) + z – H/2
The tolerances of gauge for wear limits state are (see Figure 3): ⎯
for the upper specification limit:
USL(U)GO = USL(W) + z + H/2
⎯
lower specification limit: (LSL):
LSL(U)GO = USL(W) +
α –
y
NOTE y and α represents respectively an amount outside of workpiece tolerance limits taking into account a margin of wear limits of GO gauge and a safety zone for a compensation of measurement uncertainty.
ISO/DIS 1938-1
7.3 Limit gauges for external features of size The positions of new state tolerance limits, and wear limits for limit gauges for external features of size in relation to workpiece tolerance limits are shown in Figure 4. The GO gauge specification is positioned relative to the MMLS of the workpiece tolerance. The NO GO gauge specification is positioned relative to the LMLS of the workpiece tolerance.
USL= MMLS
α
z1
z1 GO
H/2
H
H/2
H H/2
LSL = LMLS
Tolerance workpiece
upper wear limit
y1
y1
on
NO GO
H
GO
H/2 α
H
NO GO
Nominal size up to and
Nominal size above 180
included to 180 mm
mm
Figure 4 – MPL size position for GO and NOT GO gauges for workpieces of external feature of size The value for H (see Figure 4) is specific for each type of limit gauge, for workpiece tolerance grade and size and shall be taken from Table 6. The value of z1, α1 and y1 (see Figure 4) is specific for each workpiece tolerance grade and workpiece feature size. Values for z1 shall be taken from Tables 7 to 11. When a gauge (type ring) is to be used as a GO gauge of a external feature of size of a workpiece [MMLS (WP)] the requirement on size, S, of the gauge element is (see Figure 4): ⎯
⎯
The tolerances of gauge for new state are (see Figure 4): ⎯
for the upper specification limit:
USL(M)GO = USL(W) – z1 + H/2
⎯
for the lower specification limit:
LSL(M)GO = USL(W) – z1 – H/2
The tolerances of gauge for wear limits state are (see Figure 4): ⎯
for the upper specification limit :
USL(U)GO = USL(W) – z1 + H/2 + (y1 -α1 )
⎯
for the lower specification limit:
LSL(U)GO = USL(W) – z1 – H/2
ISO/DIS 1938-1
NOTE y1 and α1 represents respectively a amount outside of workpiece tolerance limits taking into account a margin of wear limits of GO gauge and a safety zone for a compensation of measurement uncertainty.
When a gauge (type ring) is to be used as a NO GO gauge of a external feature of size of a workpiece (LMLS(WP)) the requirement on size, S, of the gauge element is (see figure 4): ⎯
The tolerances of gauge for new or wear limits state are (see Figure 4): ⎯
Upper specification limit (USL): USL(M)NO GO=USL(U) NO GO=LSL(W) + α1 + H/2
⎯
Lower specification limit: (LSL): LSL(M)NO GO=LSL(U) NO GO=LSL(W) + α1 - H/2
NOTE
α is
equal to zero when the nominal value is up to or equal to 180 mm.
Table 6 — MPE for limit gauge Workpiece standard tolerance grades
IT 6
IT 8 to IT 10
IT 7
Type of gauge
IT 11 and IT 12
IT 13 to IT 16
MPE for size and form of limit gauges (given as standard tolerance grades according to ISO 286-1)
Full form cylindrical plug gauge
H or F
Segmental cylindrical bar gauge
H or F
Size H
Form 2xF
Size H
Form 2xF
Size H
Form 2xF
Size H
Form 2xF
Size H
Form 2xF
2
1
3
2
3
2
5
4
7
5
2
1
2
1
2
1
4
3
6
5
2
1
3
2
3
2
5
4
7
5
Segmental cylindrical bar gauge with reduced gauging surfaces H or F Full form spherical plug gauge
H or F
Segmental spherical plug gauge
H or F
Bar gauge
H or F
Rod gauge with spherical ends
H or F
2
1
2
1
2
1
4
3
6
5
Full form cylindrical ring gauge
H or F
3
2
3
2
4
3
5
4
7
5
3
2
3
2
4
3
5
4
7
5
3
2
3
2
4
3
5
4
7
5
Full form notch gauge Gap gauge
H or F
H or F
NOTE 1 When the size tolerance of the workpiece is given as a code according to ISO 286-1, 286-1, Tables 7 to 11 can be used directly. When the size tolerance is not given as an ISO code, the standard tolerance grade shall be defined as the standard tolerance grade corresponding to the first tolerance interval, T, given in Tables 7 to 11, lower than to the tolerance interval of the workpiece in the same range of nominal sizes. NOTE 2
The values of form limit are half the values given in Table 7, given in column 2 x F.”
When the grade 6 to 8 is associated to the letter N (6N, 7N or 8N), then the values y, y1, α and α1 are equal to zero. NOTE 1 When the size tolerance of the workpiece is given as a code according to ISO 286-1 286-1 Table 3 can be used directly. When the size tolerance is given as a +/– tolerance the tolerance grade shall be chosen as the standard tolerance grade with the first lower tolerance in the same range of nominal sizes. NOTE 2
Up to 1 mm, grades IT14 to IT18 are not provided
NOTE 3
The gauge for quality 17 and 18 are of limited usefulness in current current gauging practice.
ISO/DIS 1938-1
Table 7 — Position of specification specification for limit gauge in relation with the w orkpiece limits - Workpiece standard tolerance grades 6 Nominal dimension [mm] Above (excluded) 3 6 10 18 30 50 80 120 180 250 315 400
Up to (included) 3 6 10 18 30 50 80 120 180 250 315 400 500
Workpiece standard tolerance grades 6* T
z
z1
α/α1
y
y1
6 8 9 11 13 16 19 22 25 29 32 36 40
1 1,5 1,5 2 2 2,5 2,5 3 4 5 6 7 8
1,5 2 2 2,5 3 3,5 4 5 6 7 8 10 11
0 0 0 0 0 0 0 0 0 2 3 4 5
1 1 1 1,5 1,5 2 2 3 3 4 5 6 7
1,5 1,5 1,5 2 3 3 3 4 4 5 6 6 7
ISO/DIS 1938-1
Table 8 — Position of specification for limit gauge in relation with the workpiece limits - Workpiece standard tolerance grades 7 to 9 Nominal dimension [mm] Above (excluded)
Up to (included)
3 6 10 18 30 50 80 120 180 250 315 400
3 6 10 18 30 50 80 120 180 250 315 400 500
Workpiece standard tolerance grades 8*
7* T 10 12 15 18 21 25 30 35 40 46 52 57 63
z
α
z1
α 1
1,5 2 2 2,5 3 3,5 4 5 6 7 8 10 11
0 0 0 0 0 0 0 0 0 3 4 6 7
y y1 1,5 1,5 1,5 2 3 3 3 4 4 6 7 8 9
T 14 18 22 27 33 39 46 54 63 72 81 89 97
z
α
z1
α 1
2 3 3 4 5 6 7 8 9 12 14 16 18
0 0 0 0 0 0 0 0 0 4 6 7 9
y y1 3 3 3 4 4 5 5 6 6 7 9 9 11
T 25 30 36 43 52 62 74 87 100 115 130 140 155
9
z
α
y
z1
α 1
y1
0 0 0 0 0 0 0 0 0 4 6 7 9
0 0 0 0 0 0 0 0 0 0 0 0 0
5 6 7 8 9 11 13 15 18 21 24 28 32
Table 9 — Position of specification for limit gauge in relation with the workpiece limits - Workpiece standard tolerance grades10 to 12 Nominal dimension [mm] Above Up to (excluded) (included) 3 6 10 18 30 50 80 120 180 250 315 400
3 6 10 18 30 50 80 120 180 250 315 400 500
Workpiece standard tolerance grades 11
10 T 40 48 58 70 84 100 120 140 160 185 210 230 250
z z1 5 6 7 8 9 11 13 15 18 24 27 32 37
α
y
1
y1
0 0 0 0 0 0 0 0 0 7 9 11 14
0 0 0 0 0 0 0 0 0 0 0 0 0
α
T 60 75 90 110 130 160 190 220 250 290 320 360 400
z z1 10 12 14 16 19 22 25 28 32 40 45 50 55
α
y
1
y1
0 0 0 0 0 0 0 0 0 10 15 15 20
0 0 0 0 0 0 0 0 0 0 0 0 0
α
T 100 120 150 180 210 250 300 350 400 460 520 570 630
12
z z1 10 12 14 16 19 22 25 28 32 45 50 65 70
α
y
1
y1
0 0 0 0 0 0 0 0 0 15 20 30 35
0 0 0 0 0 0 0 0 0 0 0 0 0
α
ISO/DIS 1938-1
Table 10 — Position of specification for limit gauge in relation with the workpiece limits - Workpiece standard tolerance grades 13 to 15 Nominal dimension [mm]
Workpiece standard tolerance grades 13
Above (excluded)
Up to (included)
T
3 6 10 18 30 50 80 120 180 250 315 400
3 6 10 18 30 50 80 120 180 250 315 400 500
140 180 220 270 330 390 460 540 630 720 810 890 970
14
y
z
α
z1
α 1
y1
0 0 0 0 0 0 0 0 0 25 35 45 55
0 0 0 0 0 0 0 0 0 0 0 0 0
20 24 28 32 36 42 48 54 60 80 90 100 110
T 250 300 360 430 520 620 740 870 1000 1150 1300 1400 1550
15
y
z
α
z1
α 1
y1
0 0 0 0 0 0 0 0 0 45 55 70 90
0 0 0 0 0 0 0 0 0 0 0 0 0
20 24 28 32 36 42 48 54 60 100 110 125 145
T 400 480 580 700 840 1000 1200 1400 1600 1850 2100 2300 2500
z
α
y
z1
α 1
y1
40 48 56 64 72 80 90 100 110 170 190 210 240
0 0 0 0 0 0 0 0 0 70 90 110 140
0 0 0 0 0 0 0 0 0 0 0 0 0
Table 11 — Position of specification for limit gauge in relation with the workpiece limits - Workpiece standard tolerance grades 16 to 17 Nominal dimension
Workpiece standard tolerance grades
[mm]
16
Above (excluded)
Up to (included)
T
-
3
3
8
z
17 α
y
T
z1
α
1
y1
600
40
0
0
1000
6
750
48
0
0
6
10
900
56
0
10
18
1100
64
18
30
1300
30
50
50
z z1
18 α
y
T
α
1
y1
80
0
0
1400
1200
96
0
0
0
1500
112
0
0
0
1800
125
72
0
0
2100
1600
80
0
0
80
1900
90
0
80
120
2200
100
120
180
2500
180
250
250
z z1
α
y
α
1
y1
80
0
0
1800
96
0
0
0
2200
112
0
0
0
0
2700
125
0
0
140
0
0
3200
140
0
0
2500
160
0
0
3900
160
0
0
0
3000
180
0
0
4600
180
0
0
0
0
3500
200
0
0
5400
200
0
0
110
0
0
4000
220
0
0
6300
220
0
0
2900
210
110
0
4600
360
180
0
7200
470
230
0
315
3200
240
140
0
5200
400
200
0
8100
520
250
0
315
400
3600
280
180
0
5700
450
230
0
8900
600
280
0
400
500
4000
320
220
0
6300
500
250
0
9700
710
320
0
Proving conformance with specification for limit gauges
When proving confor mance and non-conformance to the specifications, ISO 14253-1:1998 applies when the conformance/non conformance assessment uses the analysis of a measurement result associated to its uncertainty. Uncertainty evaluation shall be performed according to ISO/IEC Guide 98-3, and more specifically according to ISO/TS 14253-2:1999. In the case of conformance/non conformance assessment use limit gauges, ISO 14253-1 does not apply: there is no result of measurement but verification “GO” or “NO GO”.
ISO/DIS 1938-1
In the case of conformance coming from a plain gauge, there is not result of measurement only verification “GO” or “NO GO” coming from use of a GO gauge or NO GO gauge. The GO gauge shall fit (go) entirely relatively to the concerned surface of the workpiece. The NO GO gauge shall not begin to fit (NO GO) relatively to the concerned surface of the workpiece. Based on the mathematical analysis of both the workpiece and gauge tolerances limits and having into account the uncertainty concept there is a risk when assessing a workpiece as conforming to specifications when using a GO gauge or NO GO gauge. This is especially true when the tolerances location of the gauge are taken into account relative to the workpiece tolerances: ⎯
In actual work this risk for a GO gauge tends to zero when taking into account the location of the GO gauge tolerances relative to the workpiece tolerances. In order to fit a gauge in a workpiece it is mechanically necessary to have a clearance between the workpiece and the GO gauge. For this reason if the verification with a GO gauge provides a statement of conformance (it fits into the workpiece) there is a low risk of a non conform workpiece (no contribution of form deviation inside the workpiece, excess of tolerance limits of the GO gauge compared with the workpiece tolerance) When the GO gauge is in wear limits there is a risk to declare as conform a workpiece that is actually non conform. For this reason it is important to carefully manage the wear limits.
⎯
For the NO GO gauge, the major risk of using the NO GO gauge is depending to the workpiece form deviation (See Figure 5). For this reason, if the verification of NO GO gauge gives a statement of conformance (it does not fit into the workpiece), there is risks that the workpiece is not conform (form deviation inside of workpiece, excess of tolerance limits of NO GO gauge compare to tolerance workpiece).
ISO/DIS 1938-1
a) for a hole
b) for a shaft Key a
GO gauge
b
NO GO gauge
c
zone form deviation of conformance risk
d
real workpiece
Figure 5 – Impact of deviation form on proving of conformance of workpiece
Limit gauges described in this International Standard are mainly intended for the verification of tolerances on rigid workpieces. The tolerances for limit gauges given in this standard are valid at the default condition for temperature in the GPS field (20 °C), see ISO 1. Limit gauges intended for other than the standard reference temperature shall be marked specially, see 10. Limit gauges shall generally be in accordance with the size specification operator specified on the technical product documentation (TPD) to be able to function as a perfect verification operator (see also Annex B, when limit gauges are used as simplified verification operators). The size specification operator shall be indicated on the TPD according to ISO 14405. Especially important for the limit gauge being a perfect verification operator for the indicated specification operator is: ⎯
Gauge type shall be correct according to the indicated specification operator, e.g. default specification or specification modifier(s)
⎯
Length of gauge element element and if relevant also the width of the gauge element shall be in accordance with the specification operator indicated on the technical product documentation (TPD).
ISO/DIS 1938-1
During the process of verification of a limit gauge, each metrological characteristic (example: size S) is evaluated, and associated with its uncertainty of measurement. This uncertainty of measurement shall be taken into account for the decision of the conformance of the plain limit gauge. The size of the gauge is associated with its uncertainty of measurement, U . This uncertainty shall be taken into account during the process of verification and for the decision “conformance” or “non conformance EXAMPLE 1 If the evaluated characteristic is a two point distance and the specification to verify verify on the workpiece workpiece is also a two point distance then the uncertainty to consider is the measurement uncertainty on the two point dist ance. EXAMPLE 2 If the the evaluated characteristic is a two point distance and the specification to verify on the workpiece workpiece is a global size of type GG distance (see ISO 14405-1) then the measurement uncertainty to consider is the measurement uncertainty on the two point distance complemented by two times the default form of the gauge.
9
General principles of gauging
To verify, by gauging, a size tolerance for a workpiece feature of size according to the indicated specification operator on the technical product documentation, two gauges shall be used, a GO gauge according to the type of size indicated by the specification operator and a NOT GO gauge according to the type of size indicated by the specification operator. The GO gauge shall pass into/over the workpiece feature without using excessive force. The gauge shall pass the total length of the feature. The NOT GO gauge shall not pass into/over the workpiece feature without using excessive force. If the verification result is an acceptance by the MMLS and the NO GO gauge it is a proof of conformance with the workpiece tolerance indicated on the technical product documentation. If the verification result is a rejection by either the GO gauge or NO GO gauge, the workpiece may be out of tolerance. It may also be inside the tolerance, but the false result is caused by a gauge that is not on the limit value of the workpiece tolerance. Limit gauges that are not on the limit value of the work piece tolerance NOTE When more than one gauge is used for gauging of the same tolerance limit (e.g. by the machine tool and in the quality function at a suppliers plant and a third gauge at the customers plant) disagreement of compliance for the workpiece may occur because of the relative large tolerances for gauges in relation to the work piece tolerance. In such cases the gauge with the size closest to the work piece tolerance limit is giving the most correct evaluation.
10 Marking Each gauge shall be legibly and permanently marked with the particulars listed below: ⎯
the workpiece tolerance limits or, alternatively, the value of the nominal size size associated with the symbol designating the tolerance class of the workpiece, or, with the lower and upper deviation of the workpiece
⎯
the type of limit gauge : GO or NO GO
EXAMPLES
20 H6 GO — -12, 1 ± 0, 15 NO GO — 12, 25 -0, 3 / 0 NO GO — 11, 95 / 12, 5 NO GO
⎯
the serial number (alphanumerical).
⎯
the manufacturer's name or trademark.
The marking shall be on other than gauging surfaces and shall not affect the metrological characteristics of the gauges. ⎯
the temperature: if the tolerance for the limit gauge is not available at 20 °C, then the temperature shall be marked.
ISO/DIS 1938-1
Annex A (informative) General application of limit gauging
The limit gauging allows checking the conformance of a limit of a specification including dimension, by a physical process without the use of mathematical tools by the user In the case of plain limit gauges, described in this standard, the limit gauging consists to check the conformance relatively to a size characteristic of a feature of size. The limit gauging is not a technique used in a measurement process to give a numerical value of a characteristic. It is a technique used in a checking process to provide only one out of two possible results (Yes/No, GO/NO GO, Conform/Not Conform, …). There are two types of limit gauging, the limit gauging of the external size relative to the maximum material, and the limit gauging of the external size relative to the least material. The using of limit gauge has advantages and disadvantages compared to other kinds of verification method (see Table A.1). Table A.1 — Advantages Advantages and disadvantages of the limit gauges Advantages
Disadvantages
-To know economically the conformance of the characteristic
- When the result is non conforming, it is impossible to know directly how we can pilot adjust the process to perform the manufacturing process
- To be very simple to utilise by a physical process. - To give a quick answer - Close to a comparison principle, allowing to reduce environment factors uncertainty - Have a very small uncertainty associated to the metrological value of the size of gauge. - Close to envelop principle, for the GO limit gauging.
- Device dedicated to a specific application not have a numerical value - The uncertainty of gauging process is economically difficult to evaluate because the uncertainty of fitting process is dependent of multi-factor the shape, the force, the operator - Not close to the requirement for the NO GO limit gauging, because depending to the shape of the workpiece (cask or diabolo): this closeness depend to the form deviation of the workpiece, which is possible to evaluate
ISO/DIS 1938-1
Annex B (informative) Description of the specific use of the various gauge types and the associated uncertainty
B.1 GO gauge A GO gauge, applied by the hand without exercising an excessive force, is ableto able to penetrate or cover completely respectively a hole or a shaft and verify it on all its length. The check by gauge of not rigid parts (such as thick walls) requires a lot of precautions; the application of too much force during the measurement can enlarge the feature and provides wrong the results.
B.2 NO GO gauge A NO GO gauge, applied to the hand without exercising an excessive force, does not begin to penetrate or to cover. The hole must be verified if possible for both extremities.
B.3 Result of limit gauging B.3.1 For the manufacturer The manufacturer uses new state gauges according to the specifications of this part 1 of ISO 1938.
B.3.2 For the customer The customer cannot refuse a workpiece verified by himself by means of a wear state gauge according to the specifications of this part of ISO 1938. Table B.1 - Specific use of the various gauge types and the associated uncertainty Type
A
B
Illustration
Full form gauge
Segmental gauge
cylindrical
cylindrical
Type of feature of size on the part
plug
bar
Cylinder
Characteristic
Check the size characteristic with GX modifier on lower limit for a cylindrical cylindrical hole
Two opposite planes
Check the size characteristic with GX modifier on lower limit for a two opposite straight line
Two opposite angular portions of cylinder
Approach to type A, with blind hole hole or for collection feature with cylindrical shape, or specification on angular portion
Two opposite planes Same as Type A
Additional component of uncertainty compared to metrological characteristic
Length of the gauge relative to the length of the workpiece
Length and angular portion of the gauge relative to the collection of one or more integral surfaces of the workpiece
ISO/DIS 1938-1
Table B.1 (end) Type
Illustration
Type of feature of size on the part
Characteristic
Additional component of uncertainty compared to metrological characteristic
C
Segmental cylindrical bar gauge with reduced gauging surfaces
Two opposite angular reduced portions of cylinder
Approach to type B, with restricted length
Length and angular portion of the gauge relative to the collection of one or more integral surfaces of the workpiece
Two opposite planes
D
Full form spherical plug gauge
Circle
Two opposite planes
E
F
Segmental gauge
spherical
plug
Size characteristic with GX ACS modifier
Same as type D on an angular portion or a collection of feature
Two opposite planes
Same as type D
Bar gauges
Rod gauge ends
None
Two points
Two opposite angular portions of circle
None
Length and width of the gauge relative to the workpiece Two opposites planes
G
Same as type A with restricted length
with
GX on the size between two opposite planes
spherical
None
Two points (LP)
ISO/DIS 1938-1
Annex C (informative) Relation to the GPS matrix model
C.1 General For full details about the GPS matrix model, see ISO/TR 14638. The ISO/GPS Masterplan given in ISO/TR 14638 gives an overview of the ISO/GPS system of which this standard is a part. The fundamental rules of ISO/GPS given in ISO 8015 apply to this standard and the default decision rules given in ISO 14253-1 apply to specifications made in accordance with this standard, unless otherwise indicated.
C.2 Information about the standard and its use This part of this International Standard provides the most important design and metrological characteristics of plain limit gauges of linear size. It specifies the most important metrological and design characteristics of plain limit gauges of linear size. Only those design characteristics which are critical to interchangeability have been assigned requirement values. The metrological characteristics are not subject to requirement values as it is the philosophy that the values of these characteristics are matters of the manufacturer and/or user. However, ISO 1938- Part1 provides definition of the metrological characteristics and states those metrological characteristics for which the manufacturer shall state a MPE or MPL value.
C.3 Position in the GPS matrix model This International standard is a global GPS standard, which influences the chain link 4, 5 of all chains of standards in the general GPS matrix, as graphically illustrated on Figure C.1. Fundamental GPS standards
Global GPS standards General GPS standards 1
4
5
6
X X
X X
X X
Radius Angle
X X
X X
X X
Form of line independent of datum Form of line dependent of datum
X X
X X
X X
Form of surface independent of datum Form of surface dependent of datum
X X
X X
X X
Orientation Location
X X
X X
X X
Circular run-out Total run-out
X X
X X
X X
Datums Roughness profile Waviness profile Primary profile
X X X X
X X X X
X X X X
Chain link number Size Distance
2
3
ISO/DIS 1938-1
Surface imperfections Edges Figure C.1 — Position in the GPS matrix model
C.4 Related standards The related standards are those of the chains of standards indicated in Figure C.1.
X X
X X
X X
ISO/DIS 1938-1
Bibliography
[1]
ISO/TR 14638 Geometrical product specifications (GPS) — Master plan
