INTERNATIONAL
STANDARD

ISO
1 93 8-2

First edition
2017-01

Geometrical product specifications
(GPS) — Dimensional measuring
equipment —

Part 2:

Reference disk gauges
Spécification géométrique des produits (GPS) — Équipement de
mesurage dimensionnel —
Partie 2: Disques de référence pour calibres

Reference number
ISO 1938-2:2017(E)
© ISO 2017


ISO 1 93 8-2 : 2 01 7(E)

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© ISO 2017, Published in Switzerland

All rights reserved. Unless otherwise specified, no part o f this publication may be reproduced or utilized otherwise in any form
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written permission. Permission can be requested from either ISO at the address below or ISO’s member body in the country o f

the requester.

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Tel. +41 22 749 01 11
Fax +41 22 749 09 47

www.iso.org

ii

© ISO 2017 – All rights reserved


ISO 1 93 8-2 : 2 01 7(E)

Contents

Page

........................................................................................................................................................................................................................................ iv
Introduction .................................................................................................................................................................................................................................. v
1
Scope ................................................................................................................................................................................................................................. 1

2
Normative references ...................................................................................................................................................................................... 1
3
Terms and definitions ..................................................................................................................................................................................... 1
4
Symbols and abbreviated terms ........................................................................................................................................................... 2
5
Design characteristics ..................................................................................................................................................................................... 2
6
Metrological characteristics ..................................................................................................................................................................... 2
7
Maximum permissible limits on metrological characteristics ............................................................................. 3
8
Marking .......................................................................................................................................................................................................................... 5
Annex A (informative) Material measure (reference) o f the working size, WS, o f a gap gauge .............. 6
Annex B (informative) Relation to the GPS matrix model .............................................................................................................. 9
Bibliography ............................................................................................................................................................................................................................. 1 1

Foreword

© ISO 2017 – All rights reserved

iii


ISO 1 93 8-2 : 2 01 7(E)

Foreword

ISO (the International Organization for Standardization) is a worldwide federation of national standards


bodies (ISO member bodies). The work o f 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 o f
electrotechnical standardization.
The procedures used to develop this document and those intended for its further maintenance are
described in the ISO/IEC Directives, Part 1. In particular the different approval criteria needed for the
di fferent types o f ISO documents should be noted. This document was dra fted in accordance with the
editorial rules of the ISO/IEC Directives, Part 2 (see www.iso .org/directives).
Attention is drawn to the possibility that some o f the elements o f this document may be the subject o f
patent rights. ISO shall not be held responsible for identi fying any or all such patent rights. Details o f
any patent rights identified during the development o f the document will be in the Introduction and/or

on the ISO list of patent declarations received (see www.iso .org/patents).

Any trade name used in this document is in formation given for the convenience o f users and does not

constitute an endorsement.

For an explanation on the meaning o f ISO specific terms and expressions related to con formity

assessment, as well as information about ISO’s adherence to the World Trade Organization (WTO)
principles in the Technical Barriers to Trade (TBT) see the following URL: http:///www.iso .org/iso/
foreword .html.

This document was prepared by Technical Committee ISO/TC 213, Dimensional and geometrical product


.
A list of all parts in the ISO 1938 series can be found on the ISO website.
This document does not include requirements for setting plug gauges and setting ring gauges, which
were dealt with in ISO/R 1938:1971, 3.9.4.
This document covers the concepts and principles developed in ISO 14978.
specifications and verification

iv

© ISO 2017 – All rights reserved


ISO 1 93 8-2 : 2 01 7(E)

Introduction
T h i s do c u ment i s a G e ome tric a l P ro duc t Sp e c i fic ation (GP S ) s ta nda rd and i s to b e regarde d a s a genera l
GP S s ta ndard (s e e I S O 14 6 3 8) . I t i n fluence s l i n ks F a nd G o f the s i ze cha i n o f s tanda rd s i n the genera l

GPS matrix. For more detailed information on the relation of this document to other standards and the
GPS matrix model, see Annex B.
T he I S O/GP S M atri x mo del given i n I S O 14 6 3 8 gi ve s an over view o f the I S O/GP S s ys tem o f wh ich th i s
do c u ment i s a p ar t. T he

fu nda menta l

ru le s o f I S O/GP S given i n I S O 8 01 5 app ly to th i s do c u ment a nd

the de fau lt de ci s ion ru le s given i n I S O 142 5 3 -1 apply to s p e ci fic ation s made i n accordance with th i s

document, unless otherwise indicated.

The terms and concepts used in this document (compared to ISO/R 1938:1971) have been changed
accord i ng to ne e d s and term i nolo g y i n the o ther GP S s tandard s .

This document deals with reference disk gauges. The use of reference disk gauges is explained in
Annex A.
NOTE

The content of Table 2

© ISO 2017 – All rights reserved

u s e s the mo d i fiers gi ven i n I S O 14 4 0 5 -1 a nd I S O 1 101 .

v



INTERNATIONAL STANDARD

ISO 1 93 8-2 : 2 01 7(E)

Geometrical product specifications (GPS) — Dimensional
measuring equipment —

Part 2:

Re ference disk gauges
1

Scope


T h i s do c u ment s p e c i fie s the mo s t i mp o r ta nt me tro lo g ic a l a nd de s i g n ch a rac ter i s tic s o f re ference

disk gauges.
This document covers linear sizes of the gauge up to 500 mm.
2 Normative references
T he

fol lowi ng

do c u ments are re ferre d to i n the tex t i n s uch a way th at s ome or a l l o f thei r content

con s titute s re qu i rements o f th i s do c u ment. For date d re ference s , on ly the e d ition cite d appl ie s . For
u ndate d re ference s , the late s t e d ition o f the re ference d do c ument (i nclud i ng a ny amend ments) appl ie s .

ISO 286-1, Geometrical product specifications (GPS) — ISO code system for tolerances on linear sizes —
Part 1: Basis o f tolerances, deviations and fits

ISO 1101, Geometrical product specifications (GPS) — Geometrical tolerancing — Tolerances of form,
orientation, location and run-out
ISO 1938-1:2015, Geometrical product specifications (GPS) — Dimensional measuring equipment — Part 1:
Plain limit gauges o f linear size
ISO 14405-1, Geometrical product specifications (GPS) — Dimensional tolerancing — Part 1: Linear sizes
ISO 17450-2, Geometrical product specifications (GPS) — General concepts — Part 2: Basic tenets,

specifications, operators, uncertainties and ambiguities

ISO/IEC Guide 98-3, Uncertainty of measurement — Part 3: Guide to the expression of uncertainty in
measurement (GUM:1995)
ISO/IEC Guide 99, International vocabulary of metrology — Basic and general concepts and associated


terms (VIM)

3 Terms and definitions
For the pu rp o s e s o f th i s do c ument, the term s a nd defi n ition s given i n I S O 2 8 6 -1 , I S O 19 3 8 -1 , I S O 14 4 0 5 -1 ,
I S O 1745 0 -2 , I S O/I E C Gu ide 9 8 -3 and I S O/I E C Guide 9 9 a nd the

fol lowi ng

apply.

ISO and IEC maintain terminological databases for use in standardization at the following addresses:
— IEC Electropedia: available at ctropedia .org/
— ISO Online browsing platform: available at .org/obp
3 .1

reference disk gauge

gauge designed and intended to determine the working size of a gap gauge
© ISO 2017 – All rights reserved

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ISO 1 93 8-2 : 2 01 7(E)

3.2

unloaded size
US


<of a gap gauge> perpendicular distance between the gauging faces of a gap gauge when the measuring
force is zero
3.3

working size
WS

<o f a gap gauge> diameter o f a disk over which the gap gauge just passes in a vertical direction under

the working load marked on it, or, if this is not indicated, under its own weight
4 Symbols and abbreviated terms

For the purposes o f this document, the symbols and abbreviated terms given in
Table 1 apply.

ISO 1938-1 and

Table 1 — Symbols and abbreviated terms
Symbols and
abbreviated terms

Hp

ref. GO-M
ref. GO-U
ref. NO GO
US
WS
5


Description

tolerance on the size characteristic, S, of a reference disk gauge
reference disk gauge for a new state GO gap gauge
reference disk gauge for a wear limits state GO gap gauge
reference disk gauge for a NO GO gap gauge
unloaded size (of a gap gauge)
working size (of a gap gauge)

Design characteristics

For the purposes o f this document, the design characteristics for gauges given in ISO 1938-1 apply.
Re ference disk gauges can be made as full form cylindrical plug gauges (gauge type A) or as segmental
cylindrical bar gauges (gauge type B).
6 Metrological characteristics

The most important metrological characteristics are the size S and the form characteristics of the

measuring feature o f the re ference disk gauge. To define the metrological characteristic on a re ference
disk gauge, the modifiers defined in ISO 14405-1 and the symbols defined in ISO 1101 shall be used.

This document describes potential metrological characteristics available on reference disk gauges. The
final decision to select one or several metrological characteristics is le ft to the user.

Table 2 gives potential metrological characteristics for reference disk gauges, 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 de fault, the two point size, S, o f the gauge limit and the
form deviation are required.


2

© ISO 2017 – All rights reserved


ISO 1 93 8-2 : 2 01 7(E)

Table 2 — List o f design and metrological characteristics for reference disk gauges
Description
Full form cylindrical plug gauge — Gauge type A

Complementary
design
characteristics

Metrological
characteristics

LG

Segmental cylindrical bar gauge — Gauge type B

LG
B

a

Default metrological characteristics to be considered.
C yl i nd ric ity (for m) tolera nce va lue (s e e I S O 1 101) .


Maximum inscribed (see ISO 14405-1).
Minimum circumscribed (see ISO 14405-1).
Two point size (see ISO 14405-1).
Common tolerance (see ISO 14405-1).
Combined zone (see ISO 1101).

7 Maximum permissible limits on metrological characteristics

The positions of tolerance limits for reference disk gauges in relation to workpiece tolerance limits are
shown in Figure 1.

© ISO 2017 – All rights reserved

3


ISO 1 93 8-2 : 2 01 7(E)

Key

1 ref. GO-M
2 ref. GO-U
3 ref. NO GO
Figure 1 — MPL size position for re ference disk gauges

The value for Hp (see Figure 1
f
f
grade and workpiece feature size and shall be taken from Table 3.
The value of z1 , α1 and y1 (see Figure 1

f
be taken from ISO 1938-1:2015, Tables 7 to 11.
The requirement on the size, S, of the gauge element shall be in accordance with the following gauge
tolerances for new and wear limits state (see Figure 1).
a) For a reference disk gauge for a new state GO gap gauge:
f
M, ref. GO-M = USLU, ref. GO-M = USLW – z1 + Hp
f
M, ref. GO-M = LSLU, ref. GO-M = USLW – z1 – Hp/2.
b) For a reference disk gauge for a wear limits state GO gap gauge:
f
M, ref. GO-U = USLU, ref. GO-U = USLW + y1 – α1 + Hp
f
M, ref. GO-U = LSLU, ref. GO-U = USLW + y1 – α1 – Hp/2.
c) For a reference disk gauge for a NO GO gap gauge:
f
M, ref. NO GO = USLU, ref. NO GO = LSLW + α1 + Hp
f
M, ref. NO GO = LSLU, ref. NO GO = LSLW + α1 – Hp/2.
) i s s p e ci fic

or re erence d i s k gauge s . I t i s b a s e d on workpie ce tolerance

) i s s p e ci fic

4

1)

or the upp er s p ec i fic ation l i m it: US L


2)

or the lower s p e ci fic ation l i m it: L S L

1)

or the upp er s p e c i fic ation l i m it: US L

2)

or the lower s p e ci fic ation l i m it: L S L

1)

or the upp er s p e c i fic ation l i m it: US L

2)

or the lower s p e ci fic ation l i m it: L S L

or e ach workpie ce tolera nce grade a nd s i ze and s ha l l

/2 ;

/2 ;

/2 ;

© ISO 2017 – All rights reserved



ISO 1 93 8-2 : 2 01 7(E)

Table 3 — Values of

Size

IT6 and IT7

Hp

IT1

H

p

and F for calculation o f MPL o f re ference disk gauges in standard
tolerance grades according to ISO 286‑1
Workpiece standard tolerance grades

Form
2×F

Size

IT8 to IT12

Hp


IT2

The form limit values are half the values given in column 2 × F.

Form
2×F
IT1

Size

IT13 to IT18

Hp

IT3

Form
2×F
IT2

When the tolerance of the dimension of a feature of size of a workpiece is given as a code according
to I S O 2 8 6 -1 : 2 010 , Table 3 and I S O 19 3 8 -1 : 2 01 5 , Table s 7 to 1 1 c a n b e u s e d d i re c tly. When the s i z e
tolerance i s no t given a s an I S O co de, the s tand ard tolera nce grade sha l l b e defi ne d as the s tandard
tolerance grade corre s p ond i ng to the fi rs t tolerance i nter va l , T, given i n I S O 19 3 8 -1 : 2 01 5 , Table s 7 to 11 ,

lower than or equal to the tolerance interval of the workpiece in the same range of nominal sizes.
When grades 6 to 8 are associated with the letter N (6N, 7N or 8N), then for the GO gap gauge and their
reference disk gauges, the values y1 and α1 are equal to zero.
8 Marking

E ach re ference d i sk gauge s ha l l b e le gibly and p erma nently marke d with the

—

fol lowi ng:

s i z e tolerance o f the workpie ce given b y

— the workpiece tolerance limits,
—

—

b y I S O co de (nom i na l s i z e va lue o f the workpie ce with the s ymb ol de s ignati ng the tolera nce

class according to ISO 286-1), or

b y the nom i na l s i z e va lue o f the workpie ce, with the lower and upp er devi ation o f the workpie ce,
or with on ly the s u itable devi ation ( lower or upp er) dep end i ng on the gauge typ e (re f. G O -M , re f.
G O - U or re f. NO G O) ;

—

the typ e o f re ference d i s k gauge:
re f. G O -M

for

a re ference d i sk gauge


for

a new s tate G O gap gauge;

re f. G O - U

for

a re ference d i sk gauge

for

a we ar l i m its s tate G O gap gauge;

re f. NO G O

for

a re ference d i sk gauge

for

a NO G O gap gauge;

EXAMPLE 1 20 g6 ref. GO-M
EXAMPLE 2 12,1 ±0,15 ref. GO-U
EXAMPLE 3 11,95/12,5 ref. NO GO
—

the s eri a l nu mb er (a lph anu meric a l) ;


— the manufacturer’s name or trademark.
The marking shall not be on gauging surfaces and shall not affect the metrological characteristics of
the gauges.

© ISO 2017 – All rights reserved

5


ISO 1 93 8-2 : 2 01 7(E)

Annex A

(informative)
Material measure (reference) o f the working size, WS, o f a gap gauge

A.1 Interpretation o f size

For gap gauges, H determines the limits of the value of the working size, WS, but not of the unloaded
s i z e US . T he worki ng s i ze o f a gap gauge, however, i s no t defi ne d with a zero me as u ri ng

force,

as

for

o ther gauge s , b e c au s e i n u s e, a gap gauge may b e regarde d a s a comp a rator wh ich e ffe c ts a tran s fer


measurement between a known dimension, e.g. a reference disk gauge and a workpiece.
I f gap gauge s are veri fie d without applyi ng the s ta nda rd i z e d me a s u ri ng

force,

e . g. b y u s i ng a co ord i nate

me a s uri ng mach i ne, then it i s ne ce s s a r y to know the ela s tic defle c tion o f the gauge b o dy i n order that
the worki ng s i z e c a n b e c a lc u late d by the me a s ure d u n lo ade d s i ze . T he me as u re d s i ze i s the s ma l le s t
d i s tance o f at le as t five me as u re d leng th s (fou r p o s ition s clo s e to the corners and one at the centre o f

the gauging faces).

6

© ISO 2017 – All rights reserved


ISO 1 93 8-2 : 2 01 7(E)

Key

1 ref. GO-M
2 ref. GO-U
3 ref. NO GO

4 new state GO gap gauge
5 NO GO gap gauge

Figure A.1 — MPL size position for gap gauges and re ference disk gauges (example for the

workpiece dimension 10 h7)
T he relation sh ip b e twe en the workpie ce s p e ci fic ation and the M PL s i z e p o s ition

for

gap gauge s a nd

reference disk gauges is shown in Figure A.1 as example for the workpiece dimension 10 h7.

NOTE The relation between the tolerance H of the gap gauge and the tolerance Hp of its reference disk gauge
is as follows.

© ISO 2017 – All rights reserved

7


ISO 1 93 8-2 : 2 01 7(E)

T he d i fference b e twe en the l i m its o f s i z e gi ven b y

H

to compensate for errors of measurement. H and Hp
f
to be regarded as correct.
accord i ng to the de fi n ition o

a nd b y


Hp

rep re s ents a s a fe ty z o ne o n b o th s ide s o f

wo rki ng s i z e , gap gauge s l ie outs ide the z one

Hp

Figure A.1). Therefore if,
Hp but within the zone H

a re there fore s ym me tr ic a l (s e e

, the y a re s ti l l

A.2 Use o f re ference disk gauges
T here are two mai n me tho d s wh ich may b e u s e d as a re ference o f the worki ng s i z e o f gap gauge s .

The two methods are as follows:
a) Reference disk gauge method
For a GO gap gauge, two reference disk gauges are used.
The GO gap gauge should pass over the reference disk gauge for a new state GO gap gauge (ref. GOf
f
contact with the reference disk gauge and then released. Inertia forces are thus avoided.
The GO gap gauge should not pass over the reference disk gauge for a wear limits state GO gap
gauge (ref. GO-U) when this is applied in the same manner described above.
The NO GO gap gauge should pass over the reference disk gauge for a NO GO gap gauge (ref. NO GO)
when this is applied in the same manner described above.
b) Reference disk gauge and gauge block method
This method uses a reference disk gauge with a diameter smaller than the working size of the gap

both GO and NO GO gap gauges. The sum of the sizes of the gauge block(s) and the reference disk
gauge shall meet the size requirement of the gauge element of the corresponding reference disk
gauge according to Clause 7.
The GO gap gauge should pass over the combined width of the gauge block(s) and the reference
disk gauge corresponding to the reference disk gauge for a new state GO gap gauge (ref. GO-M) in
f
f
with the gauge block(s) and the reference disk gauge and then released. Inertia forces are thus
avoided.
The GO gap gauge should not pass over the combined width of the gauge block(s) and the reference
disk gauge corresponding to the reference disk gauge for a wear limits state GO gap gauge (ref. GOU) when this is applied in the same manner described above.
The NO GO gap gauge should pass over the combined width of the gauge block(s) and the reference
disk gauge corresponding to the reference disk gauge for a NO GO gap gauge (ref. NO GO) when this
is applied in the same manner described above.
It is important that the gauging faces of the gap gauge, the gauge block(s) and reference disk gauge
M ) i n a ver tic a l d i re c tion, under the worki ng lo ad , a ter h avi ng b e en brought c are u l ly to re s t i n

gauge, u s e d i n conj u nc tion with gauge blo cks accord i ng to I S O 3 6 5 0 grade 1 and i s appropri ate to

a ver tica l d i re c tion, u nder the worki ng lo ad, a ter havi ng b e en brought c are u l ly to re s t i n contac t

(dep end i ng on the me tho d us e d) b e c are fu l ly wip e d cle an b e fore any me a s u rements a re p er forme d . For
re ference d i s k gauge s , it i s a l s o re com mende d that they shou ld b e gre as e d with a th i n fi l m o f p ara ffi n
j el ly and then c a re fu l ly wip e d, without comple tely removi ng the p a ra ffi n j el ly.

8

© ISO 2017 – All rights reserved



ISO 1 93 8-2 : 2 01 7(E)

Annex B

(informative)
Relation to the GPS matrix model
B.1 General

For full details about the GPS matrix model, see ISO 14638.
T he I S O/GP S M atri x mo del given i n I S O 14 6 3 8 give s an over view o f the I S O/GP S s ys tem o f wh ich th i s
do c u ment i s a p ar t. T he

fu nda menta l

ru le s o f I S O/GP S given i n I S O 8 01 5 app ly to th i s do c u ment a nd

the de fau lt de ci s ion ru le s given i n I S O 142 5 3 -1 apply to s p e ci fic ation s made i n accordance with th i s

document, unless otherwise indicated.

B.2 Information about this document and its use

This document provides the most important design and metrological characteristics of reference
disk gauges.
O n ly

tho s e

de s ign


ch arac teri s tics

wh ich

are

critic a l

to

i nterch ange abi l ity

h ave

b e en

as s igne d

re qu i rement va lue s . T he me trolo gic a l cha rac teri s tic s are no t s ubj e c t to re qu i rement va lue s as it i s
the ph i lo s ophy that the va lue s o f the s e cha rac teri s tic s are matters o f the manu fac tu rer a nd/or u s er.
H owever,

th i s

do c u ment

provide s

defi nition


o f the

me trolo gic a l

charac teri s tics

metrological characteristics for which the manufacturer states an MPL value.

and

s tate s

tho s e

B.3 Position in the GPS matrix model
T h i s do c u ment i s a glob a l GP S s tandard, wh ich i n fluence s the chai n l i n ks F a nd G o f a l l ch ai n s o f
s tandard s i n the genera l GP S matri x mo del , a s graph ic a l ly i l lu s trate d on

© ISO 2017 – All rights reserved

Table B.1.

9


ISO 1 93 8-2 : 2 01 7(E)

Table B.1 — Position in the GPS matrix model
A


B

Chain links
C

D

E

F

G

Feature
Feature Conformance Measurement Measure- Calibrations
and
ment
and requirements properties
indications
non-conformequipment
ance
•
•
S ymb ol s

Size
Distance
Form
Orientation
Location

Run-out
P ro fi le

surface
texture
Areal
surface
texture
Surface
imperfections

B.4 Related standards

The related standards are those of the chains of standards indicated in Table B.1.

10

© ISO 2017 – All rights reserved


ISO 1 93 8-2 : 2 01 7(E)

Bibliography

[1]

ISO 1, Geometrical product specifications (GPS) — Standard reference temperature for the
specification o f geometrical and dimensional properties

[2]


ISO 1302, Geometrical Product Specifications (GPS) — Indication of surface texture in technical
product documentation

[3]
[4]
[5]

ISO 3650, Geometrical Product Specifications (GPS) — Length standards — Gauge blocks
ISO 8015, Geometrical product specifications (GPS) — Fundamentals — Concepts, principles and rules
ISO 14253-1:2013, Geometrical product specifications (GPS) — Inspection by measurement

[6]
[7]

o f workpieces and measuring equipment — Part 1: Decision rules for proving con formity or
noncon formity with specifications

ISO 14638, Geometrical product specifications (GPS) — Matrix model
ISO 14978:2006, Geometrical product specifications (GPS) — General concepts and requirements
for GPS measuring equipment

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ISO 1 93 8-2 : 2 01 7(E)

ICS  17.040.10


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