o EUTSCHE NORM April1999
Micrometers
-
DIN
Part 1: Standard design external micrometers
Concepts. requirements and testing 863-1
ICS 01.040.17; 17.040.30 Supersedes
October 1983 edition.
Prüfen geometrischer GrõBen - MeBschrauben -
Teil 1: BügelmeBschrauben. Normalausführung - Begriffe.
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).
See Explanatory notes for relationship to International Standard ISO 3611. published by the International
Organization for Standardization.
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
This standard differs from the October 1983 edition in that the terminology has been harmonized with the
relevant international literature [1] and the standard has been editorially revised.
Previous editions
DIN 863: 1925-04, 1928-04, 1956-02; DIN 863-1: 1977-11, 1983-10.
Dimensions in mm
1 Scope
This standard specifies design, dimensional and performance requirements for and the testing of external
micrometers of a standard designo with measuring capacities up to 500 mm. having 0.01 mm scale intervals
or digitallncrements and a maximum span of 25 mm.
Continued on pages 2 to 6.
Translation by DIN-Sprachendienst.
Incase01doubl, lhe German-Ianguageoriginalshouldbe consulledas lheaulhorilalivelext.
@ No part 01 Ihis Iranslation may be reproduced wilhoul lhe prior permission 01 Ref. No. DIN 863-1 : 1999-04
DIN Deutsches Institutfür Normung e. V., Serlin. English
price group07SafesNo.0107
Beuth VerlagGmbH, 0-10772 Serlin, has lhe exclusive righl01sale lor German Standards (DIN-Normen). 11.99
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DIN 863-1 : 1999-04
2 Normative references
This standard incorporates, by dated or undated reference, provisions from other publications. These norma-
tive 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.
DlN 102 Reference temperatures for measuring instruments and workpieces
DIN 1319-1 Basic concepts in metrology - General concepts
DIN 1319-2 Basic concepts in metrology - Terminology relating to the use of measuring instruments
DIN 2257-1 Terminology used in dimensional metrology - Units, activities, checking instruments -
Metrological concepts
DIN EN ISO 3650 Geometrical Product Specifications (GPS) - Length standards - Gauge blocks
(ISO 3650 : 1998)
[1] International vocabulary of basic 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 concepts defined in DIN1319-1, DIN 1319-2, DIN 2257 -1 and [1]apply,
in addition to the following:
3.1.1 Maximum permissible error
Extreme value of an error permitted for micrometers as in this standard (cf. 5.21 in [1J);in this standard, termed
'limit of error' and designated as G (et. figure 3).
3.1.2 Maximum permissible error of measuring head
Limit of error for the measuring head only, Le. disregarding the effects of the anvil and frame, but including errors
due to the spindle and its guide, and the indicating device (designated as GMe).
3.2 Nomenclature
See figure 1 for nomenclature used in this standard.
4 Designation
Designation of a standard design (N) externa I micrometer in accordance with this standard with a measuring
range of 25 to 50 mm (25-50):
Micrometer DIN863 - N 25-50
5 Requirements
5.1 Limits of error and tolerances
The limits of errôr and tolerances given in table 1 shall not be exceeded. The values specified for G shall be met
at any randomly selected micrometer setting.
NOTE: Any doubling of permissible errors is precluded because the G values apply for any setting, including
those at an extreme value.
GMe shall not exceed 3 f.1macross the entire 25 mm span of the measuring range.
The parallelism tolerances given in table 1 apply where the prescribed measuring force is applied through the
ratchet drive.
5.2 Frame
The frame shall be shaped to permit the measurement of a cylinder with a diameter equal to the maximum value
of the micrometer's measuring range. It shall be sufficiently stiff so that a force of 10 N applied between the
measuring faces does not alter the distance between them by more than the permissible difference in readings
specified in table 1.
It is recommended that insulating plates be fitted to the frame to prevent body heat from being transmitted to
the frame.
*) Obtainable from Beuth Verlag GmbH, Burggrafenstral3e 6, D-10787 Berlin.
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DIN 863-1 : 1999-04
5.3 Spindle and anvil
The cylindrical part of the spindle shall have a diameter of either 6,5 mm, 7,5 mm or 8 mm. The spindle screw
thread should have a pitch of 0,5 or 1 mm. There shall be no perceptible shake between the spindle and the
nut. The spindle screw thread should be fully engaged in the nut thread over the entire measuring range. The
cylindrical part of the spindle should turn easily in its bush, but without any perceptible lateral shake.
The anvil shall project at least 3 mm from the frame, as should the spindle when the maximum value of the
measuring range is reached.
5.4 Measuring faces
Measuring faces shall be lapped and shall not have any sharp edges. They shall be flat to within 0,6 j.lm. If an
optical flat is used to determine flatness, no more than two interference rings ar bands of the same colour shall
be visible on the face.
The hardness of unalloyed steel faces shall be at least 760 HV 1, that of stainless steel faces 575 HV 5.
The designs shown are for illustrative purposes only.
3
1
6
4
5
Detail X
(design optional)
1 8
8 8 12
Spindle locking devices and indication at manufacturer's discretion.
1 Anvil 7 Analogue display
2 Spindle 8 Spindle locking device
3 Ratchet drivel) 9 Barrel
4 Frame 10 Fiducial line
5 Insulating plate 11 Thimble 1)
6 Measuring faces 12 Digital display
1) The ratchet screw may either form part of the thi.mble or be
fitted into the ratchet drive
Figure 1: External micrometer (nomenclature)
5.5 Spindle locking device
The spindle locking device shall be designed so that it locks the spindle without altering the distance between
the measuring faces by more than 2 ~lm and without causing the parallelism tolerance to be exceeded.
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DIN 863-1 : 1999-04
5.6 Ratchet drive
The spindle shall be driven by means of a ratchet drive, whereby the force exerted by the drive on the measuring
faces shall be between 5 and 10 N.
5.7 Scales
5.7.1 Thimble
The thimble should have a scale with 50 or 100divisions, with scale intervals of 0,01 mm. The scale marks shall
be cleanly cut. The scale spacing shall be at least 0,8 mm, and the scale mark thickness at least 0,08 mm but
no greater than 0,2 mm. If the thimble is bevelled, the angle of the bevel should be between 10° and 20° (see
figure 2).
The distance between the barrel and the thimble surface shall not exceed 0,3 mm (see figure 2).
Table 1: Micrometer characteristics
Parallelism tolerance of measuring faces for a
Frame strength, as
measuring force of 5 to 10 N
Measuring Limit of error, difference in readings
range, in mm GI), in 11m for a force of 10 N,
Number of interference rings or Tolerance,
in 11m(ct. subclause 6.5)
bands (when using optical flats) in lm
O to 25 4 6 2 2
25 to 50 4 6 2 2
50 to 75 5 10 3 3
75 to 100 5 10 3 3
100 to 125 6 - 3 4
125 to 150 6 - 3 5
150 to 175 7 - 4 6
175 to 200 7 - 4 6
200 to 225 8 - 4 7
225 to 250 8 - 4 8
250 to 275 9 - 5 8
275 to 300 9 - 5 9
300 to 325 10 - 5 10
325 to 350 10 - 5 10
350 to 375 11 - 6 11
375 to 400 11 - 6 12
400 to 425 12 - 6 12
425 to 450 12 - 6 13
450 to 475 13 - 7 14
475 to 500 13 - 7 15
1) In normal metrological practice, symmetricallimits of error are given and a single value is specified.
However, it is not recommended here to precede the value with the :!: sign, as was done formerly. The
limits of error specified here include errors of the measuring.head, flatness and parallelism deviations ot
the measuring faces, and any errors caused by bending ot the trame.
5.7.2 Barrel
The thickness of the tiducialline and the scale marks on the barrel shall not differ by more than 30 ~lm from that
of the scale marks on the thimble.
For micrometers with spindles having a 0,5 mm thread pitch, the 0,5 scale marks shall extend both above and
below datum line to clearly distinguish them from the 1 mm marks.
1 Scale
2 Thimble
3 Barrel
Figure 2: Barrel and thimble design
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DIN 863-1 : 1999-04
5.8 Digital display
Digital displays shall be designed so that the measured value is clearly indicated at any spindle position.
5.9 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.
5.10 Setting the reading
The zero and end values of external micrometers are set by the manufacturer. Where the measured value varies
with the position of the micrometer, the manufacturer shall either set the reading for the horizontal position, or
set it for another position, which shall be indicated.
5.11 Setting gauge
The length tolerance for the setting standard shall be js 3.
5.12 Materiais
The micrometer materiais shall be selected by the manufacturer as follows:
a) The frame shall be of steel, malleable iron, or an equivalent material.
b) The spindle and anvil shall be of an alloyed toei steel or equivalent material. The measuring faces may
be of hardmetal or another equivalent hard material.
5.13 Reference temperature
The reference temperature shall be 20°C in accordance with DIN 102.
6 Testing
6.1 Limits of error G
Use grade 1 gauge blocks as in DIN EN ISO 3650 to check compliance with the limits of error specified in
table 1.
Gauge block combinations should be selected which permit testing of spindles at points which are integral
multiples of the nominal pitch, as well as at intermediate positions. The following series of blocks is suitable
(values in mm): 2,5 - 5,1 - 7,7 - 10,3 - 12,9 - 15,0 - 17,6 - 20,2 - 22,8 - 25. Values obtained at different angles
of rotation of the spindle using these blocks can also be used to determine any periodic errors.
The gauge blocks mentioned above may also be used to determine errors of indication of micrometers whose
initial value is greater than zero. Here, the length of the block(s) should be the same as the initial value of the
measuring range.
6.2 Limts of error GMc
Since the measuring head of external micrometers is not used separately, its limits of error need not be checked.
6.3 .Flatness of measuring faces
Check the flatness of measuring faces by means of an optical flat positioned so that the number of interference
rings or bands is as small as possible, or there are closed rings.
An edge zone having a width of 0,4 mm shall be disregarded.
6.4 Parallelism of measuring faces
The parallelism of the measuring faces of micrometers with measuring ranges from O to 25 mm, 25 to 50 mm,
50 to 75 mm and 75 to 100 mm shall be tested using a set of three or four optical flats whose lengths are about
one-third or one-fourth of the spindle pitch, so that measurements may be carried out at three or four points,
respectively, along the full rotation of the spindle. The ratchet drive should be used to place flats between the
measuring faces. Carefully move the flat between the measuring faces, and determine the smallest number of
interference rings or bands visible on each face. The sum of rings ar bands counted on both faces shall not
exceed the value given in table 1.
Another means of testing parallelism may be used (e.g. with an autocollimator), although in this case, the fact
that no measuring force is applied shall be taken into consideration. This procedure is primarily used for
micrometers with initial values above 100 mm
An edge zone having a width of 0,4 mm shall be disregarded.
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DIN 863-1 : 1999-04
6.5 Strength of frame
To check the strength of the frame, fasten it at a point near the anvil and apply a force of 100 N to a point on
the frame near the spindle. Note the difference in readings taken in the loaded and unloaded conditions, and
calculate this difference for a force of 10 N.
7 Marking
Micrometerscomplying 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.
A suitable space shall be provided on the micrometer for additional markings.
Umit of error Maximum error
5
4
3
2 x
x x
E 1
:::. O
.~ -1 x x x x
e -2 Umit of error
w -3
/
-4
-5 I I I I I I I I I I
O 2,5 5,1 7,7 10,3 12,9 15 17,6 20,2 22,8 25
Lengthof gaugeblock, in mm -
Figure 3: Limits of error for a micrometer with a measuring range of O mm to 25 mm, set at zero
Appendix A
Information on use
A.1 To obtain reliable results, the spindle should be carefully rotated, without jerking, with the help of the
ratchet drive.
A.2 To avoid heat transfer from the hand, the micrometer should be held by the insulating plate whenever
possible.
A.3 The micrometer should be checked for wear or defects periodically (the intervals between tests will
depend on the frequency and conditions of use).
Jerking movements of the spindle indicate the presence of dirt in the screw. Sticking of the spindle may also
be caused by coaxiality errors of the nut thread and cylindrical guide section of the frame. Alternating tightening
and slackening of the spindle during rotation indicates a bent spindle and/or coaxiality defect of the thimble
and barrel (causing wear on the barrel).
Appendix B
Explanatory notes
This standard is largely in agreement with ISO 3611, with the following exceptions:
a) The ISO Standard only specifies limit errors for micrometers for the zero setting. Errors for other settings
are listed in an annex, which can be used as a reference if the limits for the zero setting are not exceeded.
Here, however, it was not thought advisable to specify the most important requirements in an annex.
Therefore, this standard specifies limits of error for any randomly selected setting, which are given in the
body of the text (table 1). The limits of error for the zero setting specified in the ISO Standard have not been
adopted here.
b) The parallelism tolerances specified in the ISO Standard for micrometers with an initial value of 100 mm
or greater were considered as being toa wide and were thus narrowed in this standard.
c) The ISO hardness requirement for unalloyed steel measuring faces (750 HV 1) was increased to
760 HV 1 in this standard, but the hardness for stainless steel was reduced here to 575 HV 5, as it is scarcely
possible to harden stainless steel further.
d) The flatness tolerances in the ISO Standard have been narrowed here.
By making these changes, the needs of German industry (i.e. stricter requirements) have been meto
