o EUTSCHE NORM April1999
Micrometers
-
DIN
Part 4: Internal micrometers
Concepts, requirements and testing 863-4
ICS 01.040.17; 17.040.30 Supersedes
June 1981 edition.
Prüfen geometrischer GrõBen - MeBschrauben -
Teil 4: InnenmeBschrauben - Begrifte, Anforderungen, Prüfung
In keeping with current practice in standards published by the International Organization for Standardization
(ISO), a comma has been used throughout as the decimal marker.
Foreword
This standard has been prepared by the NormenausschuB Technische Grundlagen (Fundamentais in
Technology Standards Committee).
The DIN 863 series of standards comprises the following:
Part 1: Standard design external micrometers - Concepts, requirements and testing
Part 2: Fixed micrometers and depth micrometers - Concepts, requirements and testing
Part 3: Special design external micrometers - Designs, requirements and testing
Part 4: Internal micrometers - Concepts, requirements and testing
Amendments
The following amendments have been made to the June 1981 edition.
a) The terminology has been harmonized with the relevant internationalliterature [1].
b) Specifications regarding repeatability have been modified.
c) The standard has been editorially revised.
Previous edition
DIN 863-4: 1981-06.
1 Scope
This standard specifies design, dimensional and performance requirements for and the testing of internal
micrometers with measuring capacities up to 500 mm, having 0,01 mm scale intervals or digital increments
and a span of 25 mm.
2 Normative references
This standard incorporates, by dated ar undated reference, provisions from other publications. These
normative references are cited at the appropriate places in the text, and the titles of the publications are
listed below. For dated references, subsequent amendments to or revisions of any of these publications
apply to this standard only when incorporated in it by amendment or revision. For undated references, the
latest edition of the publication referred to applies.
DIN 102 Reference temperatures for measuring instruments and workpieces
DIN 878 Dial gauges
DIN 1319-1 Basic concepts in metrology - General concepts
DIN 1319-2 Basic concepts in metrology - Terminology relating to the use of measuring instru-
ments
Continued on pages 2 to 7.
Translation by DIN-Sprachendienst.
In case 01doubl. lhe German-Ianguage original should be consulled as lhe aulhorilative texto
@ No part 01 this Iranslation may be reproduced without lhe prior permission 01 Ref. No. DIN 863-4 : 1999-04
DIN Deulsches Institui (ür Normung e. V.. Serlin. English price group 08 Sales No. 0108
Beulh Verlag GmbH, 0-10772 Serlin, has lhe exclusive right 01 sale lor German Slandards (DIN-Normen). 11.99
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DIN 863-4 : 1999-04
DIN 2250-1 GO ring gauges and setting ring gauges from 1 to 315 mm nominal diameter, for general
purposes and pneumatie length measuring instruments
DIN 2257-1 Terminology used in dimensional metrology - Units, aetivities, eheeking instruments -
Metrological eoneepts
DIN 4768 Determination of surfaee roughness parameters H", H/' and H""", using eleetrie stylus
instruments - Coneepts and measuring eonditions
DIN EN ISO 3650 Geometrical Product Speeifieations (GPS) - Length standards - Gauge bloeks
(ISO 3650 : 1998)
[1] International voeabulary of basie and general terms in metrology (VIM), pUblished by the International
Organization for Standardization (ISO), 1993.*)
3 Terminology
3.1 Concepts
For the purposes of this standard, the eoneepts defined in DIN1319-1, DIN 1319-2, DIN 2257-1 and [1] apply,
in addition to the following:
3.1.1 Internal micrometer
A deviee with an integrated, threaded material measure, used to measure internal dimensions (sueh as bores).
Internal micrometers with 3-point eontaet on the object of measurement have retraetable eontaet plungers with
eonieal measuring elements.
3.1.2 Maximum permissible error
Extreme value of an error permitted for mierometers as in this standard (cf. 5.21 in [1)); in this standard, termed
'Iimit of erro r' and designated as G.
3.1.3 Repeatability (of a measuring instrument)
Ability of a measuring instrument to provide elosely similar indieations for repeated applieations of the same
measurand under the same eonditions of measurement (from (1)).
3.2 Nomenclature
See figures 1 to 3 for nomenclature used in this standard.
4 Designation
Designation of a type
A2 internal mierometer (A2) in aeeordanee with this standard with a measuring range of
100 to 125 mm (100-125):
Micrometer DIN 863 - A2 - 100-125
5 Requirements
5.1 Scales
5.1.1 Thimble
The thimble should have a seale with 50 or 100 divisions, with seale intervals of 0,01 mm. The seale marks shall
be cleanly eut. The seale spaeing shall be at least 0,8 mm, and the seale mark thickness at least 0.06 mm but no
greater than 0,2 mm. If the thimble is bevelled, the angle of the bevel shall be between 10: and 20~ (see figure 4).
The distanee between the barrel and the thimble surfaee should not exceed 0,3 mm (see figure ~\.
5.1.2 Barrel
The thickness of the fiducialline and the seale marks on the barrel shall not differ by more than 30 ~lm from that
of the seale marks on the thimble.
For mierometers having a 0,5 mm serew thread piteh, the 0,5 seale marks shall extend both above and below
the fidueial line to elearly distinguish them from the 1 mm marks.
5.2 Digital display
Digital displays shall be designed so that the measured value is elearly indieated at any spindle position.
5.3 Design features of internal micrometers with 2-point contact (types A and B)
5.3.1 Spindle
The spindle serew thread should have a piteh of 0,5 or 1 mm. There shall be no pereeptible shake oetween the
spindle and the nut. The spindle serew thread shall be fully engaged in the nut thread over the entire measuring
range.
') Obtainable from Beuth Verlag GmbH, BurggrafenstraBe 6, D-10787 Berlin.
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DIN 863-4 : 1999-04
5.3.2 Spindle locking device
If a spindle locking device is provided, it shall be designed so that it locks the spindle without altering the
distance between the measuring faces by more than 2 ~m.
5.3.3 Anvil
Anvils may be adapted to special measuring purposes, for instance by fitting them with threaded inserts for
thread measurement.
In the case of type B micrometers, the measuring force shall be applied to the anvil in the direction of meas-
urement only. The anvil may be interchangeable, allowing measurement outside of the micrometer axis.
5.3.4 Measuring faces
Measuring faces of type A and B micrometers shall be rounded, and their radius shall be less than half the lowest
value of the measuring range.
5.3.5 Extensions
The measuring range of type A2 and B micrometers may be increased by means of extensions, which may have
integrated circular gauge blocks as material measures. The measuring faces of the blocks shall be such that,
in each case, a rounded measuring face comes in contact with a flat one. Connecting elements which join
extensions to each other and to the micrometer shall be designed to ensure a rigid connection.
The designs shown are for iIIustrative purposes only.
Type A1
Type A2 (with extension)
x
-----
1 1
3
Detail X
4 (design optional)
ffi~-I \
9
Spindle locking device and indication at manufacturer's discretion.
1 Measuring face 6 Barrel
2 Anvil 7 Fiducial line
3 Extension 8 Thimble
4 Analogue display 9 Digital display
5 Spindle locking device
Figure 1: Internal micrometer with 2-point contact (nomenclature)
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DIN 863-4 : 1999-04
The designs shown are for illustrative purposes only.
Type B
Detail X3)
5
3 4
1 Adjustable tolerance marks
2 Adjustable anvil
3 Measuring device (e.g. DIN 878 dial gauge)
4 Dial indicator
5 Fiducial line
6 Separation point for extensions
7 Anvil
3) Detail X as in figure 1.
Figure 2: Internal micrometer with adjustable anvil and 2-point contact (nomenclature)
5.4 Design features of interna I micrometers with 3-point contact (type C)
5.4.1 Measuring faces
For testing cylindrical bores, the three measuring faces of the micrameter shall be cylindrical so that there is
linear contact along the face of the object of measurement. The radius of the faces shall be less than half of the
lowest value of the measuring range.
For special measuring purposes, measuring heads or contact plungers may be interchangeable. The shape of
the measuring faces shall be adapted to the measuring purpose (e.g. thread measurements).
5.4.2 Ratchet drive
Micrometers shall be fitted with a ratchet drive to ensure centring and alignment in every pasition.
The force acting on the measuring faces shall be specified by the manufacturer. The actual forces for microm-
eters of the same type, the same measuring range, and produced by the same manufacturer shall not fluctuate
by more than 50 %.
5.4.3 Extensions
It should be possible to extend the length of the micrometers in order to reach into deep or deep-Ievel bores.
The separation point of the micrometer shall guarantee a reliable connection. Each time an extension is used,
the micrometer shall be reset, since extensions for this type of micrometer normally are not material measures,
as are the ones described in subclause 5.3.5.
5.5 Material and design
Micrometer elements establishing and registering the dimension shall be of an alloyed toei steel or equivalent
material. Measuring faces and other elements subjects to wear within the measuring section may be of
hardmetal ar another equivalent hard material.
Measuring faces should not have any sharp edges. In terms of surface roughness, the ten point height of
irregularities, Rz' as defined in DIN 4768, shall be 0,8 ~lm ar lower. The hardness of the faces shall be at least
760 HV 1 (equivalent to 62 HRC).
5.6 Adjusting devices
Every micrometer shall be provided with devices to adjust the zero setting and to compensate for wear of the
spindle and nut threads. It shall be possible for the user to operate these devices.
5.7 Setting the reading
The zero and end values of internal micrometers are set by the manufacturer.
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DIN 863-4 : 1999-04
Type C1
1,
Detail Xa)
4
2
Type C2 (with measuring faces facing forward)
1
Detail Xa)
2
1 Contact plungers
2 Measuring face
3 Separation point for extensions
4 Ratchet drive
a) Detail X as in figure 1 (but without locking device),
Figure 3: Internal micrometer with 3-line contact (nomenclature)
x 10° to 20°
ro
E
(')
o
3
1 Scale
2 Thimble
3 Barrel
Figure 4: Barrel and thimble design
5.8 Limits of error and tolerances
The limits of error specified in table 1 shall not be exceeded, and shall be met at any randomly selected setting
and - in the case of type A2 micrometers - with any randomly selected extension,
NOTE: Any doubling of the limits of error is precluded because the specified values apply for any setting,
including those at an extreme value,
For extensions used with 2-point micrometers, the length tolerance shall be js 2.
For type B micrometers, the repeatability limit, r, 01 the measuring device (e,g, dial gauge) shall be taken into
consideration.
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DIN 863-4 : 1999-04
5.9 Reference temperature
The reference temperature shall be 20°C in accordance with DIN 102.
6 T esting
6.1 Limits of error G
Inthe case of 2-point micrometers, the limitsof error may be checked with ring gauges as in DIN 2250-1 or with
another type of material measure, such as fixed calipers, gauge blocks or measuring jaws, or checked between
the measuring faces of another dimensional measuring instrumento
Ring gauges shall be manufactured to JS 3.
The limitsoferror of 3-point micrometers may also be checked withsetting ringgauges as in DIN 2250-1. Where
it is difficult to produce such gauges (e.g. when the gauges are to have a nominal size greater than 200 mm).
other material measures may be used, as longas these can ensure a reliable positioning of the micrometer's
measuring faces. In any case, the measuring faces shall be completely encompassed by the material measure.
Gauges shall be manufactured to JS 3.
Materialmeasures should be selected which permit testing at points which are integral multiples of the nominal
pitch, as well as at intermediate positions. This way. values obtained at difterent angles of rotation of the spindle
can also be used to determine any periodic errors.
6.2 Repeatability of types B and C micrometers
The repeatability of types B and C micrometers can be checked by means of setting gauges as in DIN 2250-1
or with special material measures. It should be noted that, in the latter case, deviations of form of the material
measure may influence results.
Repeatability shall be checked at three points distributed over the entire measuring range. Five measurements
shall be taken at each point; the maximum difference between the five results shall not be greater than the values
specified for repeatability limit, r.
Table 1: Limits of errar, G
Type A and B
Type C micrometers2)
micrometers 1)
Measuring range, in mm
Limits of erro r, Limits of error, Repeatability limit,
G, in 11m G. in Im r. in 11m
3 to 10 - 4 4
Over 10 up to 50 4 4 4
Over 50 up to 100 5 5 5
Over 100 up to 150 6 6 6
Over 150 up to 200 7 7 7
Over 200 up to 250 8 8 8
Over 250 up to 300 9 9 9
Over 300 up to 350 10 - -
Over350 up to 400 11 - -
Over 400 up to 450 12 - -
Over 450 up to 500 13 - -
1) These values apply only to measurements taken along the instrument axis. For micrometers with an
adjustable anvil, the repeatability values for the integrated material measure apply.
2) Since ali other errors are included in the repeatability limit, r and G have the same value.
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DIN 863-4 : 1999-04
Limit of error Maximum error
5
4
3
2 x
x x
S 1
.2" O
...: -1 x
o
tE -2
-3
Limit of error
-4
-5
'80
Conventionaltrue valueof dimension,in mm -
Figure 5: Limits of error for a micrometer with a measuring range of 80 mm to 90 mm,
set at the lowest value
6.3 Length of gauge blocks af extensions for types A and B micrometers
The length of gauge blocks for extensions can be checked either using gauge blocks of grade O as in
DIN EN ISO 3650 or with a suitable length measuring device.
7 Marking
Micrometers complying with this standard shall be legibly and permanently marked with the following informa-
tion:
- scale interval or digital increment;
- measuring range;
- manufacturer's trademark or name.
Extensions for types A and B micrometers with 2-point contact shall be marked with the nominal length.
Appendix A (informative)
Informationon use
A.1 Considerable skill and experience are required to obtain reliable results when using a 2-point micrometer
to find a maximum dimension. Internal micrometers with adjustable anvils usually indicate the maximum value
without the intervention of the tester.
With 3-point internal micrometers, the measuring head should be placed over tbe bore, and then the micrometer
inserted by quickly rotating it with the help of the ratchet drive.
A.2 When using the 2-point micrometer to take measurements in the horizontal position, support should be
provided at the Bessel points, as shown in figure A.1, to limit bending of the instrument as much as possible,
especially in the case of large nominal dimensions.
A.3 Internal micrometers with 3-point contact should not be just set to one value and then used in the same
way as a plug gauge.
A.4 3-point micrometers should not be left in the bore longer than necessary because it is possible that the
object of measurement has become heated during the previous processing stage and the micrometer could
become stuck in the bore during the cooling-down stage. The contact plungers should be retracted before the
micrometer is removed from the bore.
A.5 Internal micrometers should be checked for wear or defects periodically (the intervals between checks
will depend on the frequency and conditions of use).
Figure A.1: Supporting micrometer to ensure minimum bending
