ISO 4468:2020
(Main)Gear hobs — Accuracy requirements
Gear hobs — Accuracy requirements
This document specifies requirements for the accuracy of general-purpose hobs of 0,5 module to 40 module. These hobs are intended for producing gears which conform to ISO 53 and ISO 54. This document applies to hobs for spur and helical gears. It applies to solid (monobloc) and inserted blade hobs. The elemental features of hobs are graded according to accuracy, as follows: — Grade 4A; — Grade 3A; — Grade 2A; — Grade A; — Grade B; — Grade C; — Grade D. Grade 4A is the highest order of precision. In addition to the elemental tests for hobs, this document gives permitted tolerances for composite tests that are taken along the cutting edges on the line of action. The two groups of tests are not equivalent and one can choose between one or the other. If there was no previous agreement, the hob is regarded as belonging to the precision class specified if it satisfies one or the other of the two methods of inspection. NOTE The tolerances in this document were determined for gear hobs whose dimensions conform to ISO 2490, but with certain precautions they can be applied to hobs not specified in this document.
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INTERNATIONAL ISO
STANDARD 4468
Third edition
2020-07
Gear hobs — Accuracy requirements
Fraises-mères — Exigences d'exactitude
Reference number
ISO 4468:2020(E)
©
ISO 2020
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ISO 4468:2020(E)
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ii © ISO 2020 – All rights reserved
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ISO 4468:2020(E)
Contents Page
Foreword .iv
1 Scope . 1
2 Normative references . 1
3 Terms, definitions and symbols . 2
3.1 Terms and definitions . 2
3.2 Symbols . 4
4 Allowable deviations . 4
5 Derivation of allowable values . 5
5.1 General . 5
5.2 Tests 1-6, 9, 12, 13 and 14 . 6
5.3 Test 7. 6
5.4 Test 9A . 6
5.5 Tests 10 . 6
5.6 Tests 8, 8A, 9B, 11, 11A, 12, 15 and 16 . 6
5.7 Oversize tolerances . 6
5.8 All tests . 7
Annex A (normative) Nominal dimensions of general-purpose single-start solid
(monobloc) gear hobs with axial keyway or tenon drive of 0,5 to 40 module .30
Bibliography .39
© ISO 2020 – All rights reserved iii
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ISO 4468:2020(E)
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.
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
different types of ISO documents should be noted. This document was drafted 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 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. Details of
any patent rights identified during the development of 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 information given for the convenience of users and does not
constitute an endorsement.
For an explanation of the voluntary nature of standards, the meaning of ISO specific terms and
expressions related to conformity assessment, as well as information about ISO's adherence to the
World Trade Organization (WTO) principles in the Technical Barriers to Trade (TBT), see www .iso .org/
iso/ foreword .html.
This document was prepared by Technical Committee ISO/TC 60, Gears, Subcommittee SC 1,
Nomenclature and wormgearing.
This third edition cancels and replaces the second edition (ISO 4468:2009), which has been technically
revised. It also incorporates the Technical Corrigendum ISO 4468:2009/Cor 1:2009.
The main changes compared to the previous edition are as follows:
— oversize tolerances: when the hob outside diameter exceeds the recommended size given in
ISO 2490, the standard tolerances shall be increased by a factor of one-half of the percent oversize;
— hob sizes: the standard hob sizes from ISO 2490 were added as Annex A.
Any feedback or questions on this document should be directed to the user’s national standards body. A
complete listing of these bodies can be found at www .iso .org/ members .html.
iv © ISO 2020 – All rights reserved
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INTERNATIONAL STANDARD ISO 4468:2020(E)
Gear hobs — Accuracy requirements
1 Scope
This document specifies requirements for the accuracy of general-purpose hobs of 0,5 module to 40
module.
These hobs are intended for producing gears which conform to ISO 53 and ISO 54.
This document applies to hobs for spur and helical gears. It applies to solid (monobloc) and inserted
blade hobs.
The elemental features of hobs are graded according to accuracy, as follows:
— Grade 4A;
— Grade 3A;
— Grade 2A;
— Grade A;
— Grade B;
— Grade C;
— Grade D.
Grade 4A is the highest order of precision.
In addition to the elemental tests for hobs, this document gives permitted tolerances for composite
tests that are taken along the cutting edges on the line of action. The two groups of tests are not
equivalent and one can choose between one or the other. If there was no previous agreement, the hob is
regarded as belonging to the precision class specified if it satisfies one or the other of the two methods
of inspection.
NOTE The tolerances in this document were determined for gear hobs whose dimensions conform to
ISO 2490, but with certain precautions they can be applied to hobs not specified in this document.
2 Normative references
The following documents are referred to in the text in such a way that some or all of their content
constitutes requirements of this document. For dated references, only the edition cited applies. For
undated references, the latest edition of the referenced document (including any amendments) applies.
ISO 286-2, Geometrical product specifications (GPS) — ISO code system for tolerances on linear sizes —
Part 2: Tables of standard tolerance classes and limit deviations for holes and shafts
ISO 1122-1, Vocabulary of gear terms — Part 1: Definitions related to geometry
ISO 2768-1, General tolerances — Part 1: Tolerances for linear and angular dimensions without individual
tolerance indications
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ISO 4468:2020(E)
3 Terms, definitions and symbols
3.1 Terms and definitions
For the purposes of this document, the terms and definitions given in ISO 1122-1 apply.
ISO and IEC maintain terminological databases for use in standardization at the following addresses:
— ISO Online browsing platform: available at https:// www .iso .org/ obp
— IEC Electropedia: available at http:// www .electropedia .org/
3.1.1
radial runout of hub diameter
total deviation in radial distance of the hub periphery from the axis
3.1.2
axial runout of hub face
total axial deviation of the hub face from a true plane of rotation
3.1.3
radial runout of tips of teeth
total deviation in the radial distance from the axis to the tips of the hob teeth
3.1.4
straightness and radial alignment over cutting depth
angular relationship between the tooth face and a radial line intersecting the tooth face at the hob
outside diameter, measured in a plane perpendicular to the axis
3.1.5
adjacent spacing of cutting face of gashes
maximum deviation between any two consecutive cutting face measurements
3.1.6
total spacing of cutting face of gashes
maximum deviation between any two cutting face measurements
3.1.7
gash lead deviation per 100 mm
maximum deviation as the probe contacts the tooth faces within the axial region of the gash
Note 1 to entry: Allowable values for deviations are given per 100 mm of cutting face width.
3.1.8
tooth profile deviation
maximum deviation of the portion of the hob tooth that generates an unmodified involute profile
3.1.9
tooth thickness
normal tooth thickness difference of the actual and reference datum at the reference cylinder
Note 1 to entry: Tooth thickness is negative only.
3.1.9.1
addendum
radial distance between the top of the hob tooth and the reference cylinder.
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ISO 4468:2020(E)
3.1.9.2
tooth thickness difference along one gash
difference between the maximum and minimum nominal tooth thickness (3.1.9) along one gash at the
reference cylinder
Note 1 to entry: Test 9B is used for tooth thickness difference along one gash. This test is only valid for quality
Grades 4A, 3A and 2A (see Table 6).
3.1.10
lead deviation on adjacent teeth
maximum lead deviation between any two consecutive teeth
3.1.11
lead deviation in one axial pitch
maximum deviation between any two teeth within any group of consecutive teeth contained in one
axial pitch
Note 1 to entry: The number of teeth in one axial pitch is the number of teeth encountered by the measurement
probe as it moves parallel to the reference axis during lead testing for a distance of one axial pitch of the hob.
Note 2 to entry: Hobs having one thread:
Measuring distance = one axial pitch = one revolution
Hobs having two threads:
Measuring distance = one axial pitch = 1/2 revolution
Hobs having three threads:
Measuring distance = one axial pitch = 1/3 revolution, etc.
Note 3 to entry: The number of teeth is determined by the number of gashes, the number of threads and, in the
case of helical gash hobs, the gash lead.
Note 4 to entry: Test 11A is used for lead deviation in one axial pitch when the line of action test is used.
3.1.12
lead deviation in three axial pitches
maximum lead deviation between any two teeth contained in three axial pitches
Note 1 to entry: The number of teeth in three distance of three axial pitches of the hob axial pitches is that number
of teeth encountered by the measurement probe as it moves parallel to the reference axis during lead testing for
a distance of three axial pitches of the hob.
Note 2 to entry: The number of teeth is determined by the number of gashes, the number of threads and, in the
case of helical gash hobs, the gash lead.
3.1.13
adjacent deviation along line of action
maximum deviation between any two consecutive teeth of a given line of action test
Note 1 to entry: Adjacent hob line of action allowable deviation can be applied to adjacent line of action test
results in those cases where the hob has been specified to be manufactured with involute helicoid geometry.
3.1.14
total deviation along line of action
total maximum deviation between any two teeth of a given line of action test
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ISO 4468:2020(E)
3.1.15
axial pitch deviation from thread to thread
maximum axial pitch deviation between any two consecutive teeth contained within two gashes
Note 1 to entry: For an odd number of threads, the angle between the gashes is approximately 90°. For an even
number of threads, it is approximately 120°.
3.1.16
axial pitch deviation in any three axial pitches over all threads
maximum axial pitch deviation over any three adjacent teeth contained within two gashes
Note 1 to entry: For an odd number of threads, the angle between the gashes is approximately 90°. For an even
number of threads, it is approximately 120°.
3.2 Symbols
D hob outside diameter given by Annex A for the given module
D hob oversize outside diameter
o
K ratio for test element (see Table 3)
e
K ratio for division of module (see Table 4)
m
K ratio for grade (see Table 3)
g
K ratio for number of threads (see Table 5)
t
K standard tolerance for the test
tol
K calculated value for test i
i
K deviation test 9
9d
α hob normal pressure angle
h
4 Allowable deviations
Hobs shall conform to the requirements of Tables 2 and 4, as appropriate. The hob sizes shall be in
accordance with Annex A.
When prior agreement between the hob manufacturer and purchaser specifies measurement of hobs,
the manufacturer should select:
— the measurement method to be used from among the applicable methods described in this document
and summarized in Table 1;
— the piece of measurement equipment to be used by the selected measurement method, provided it
is in proper calibration;
— the individual teeth to be measured, as long as they are approximately equally spaced.
No particular method of measurement or documentation is considered mandatory. When applications
require measurements beyond those recommended in this document, it is recommended to negotiate
special measurement methods prior to manufacturing the hob.
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ISO 4468:2020(E)
Table 1 — Reference for measurement methods
a
Test number
Test method
Test description
definition b
Elemental test Composite test
Radial runout of hub
3.1.1 1 1
diameter
3.1.2 Axial runout of hub face 2 2
Radial runout of tips of
3.1.3 3 3
teeth
Straightness and radial
3.1.4 alignment over cutting 4 4
depth
Adjacent spacing of cutting
3.1.5 5 5
face of gashes
Total spacing of cutting
3.1.6 6 6
face of gashes
Gash lead deviation per
3.1.7 7 7
100 mm
3.1.8 Tooth profile deviation 8 8A
3.1.9 Tooth thickness 9 9
Addendum difference
of values related to the
3.1.9.1 9A 9A
designed normal tooth
thickness
Tooth thickness difference
3.1.9.2 9B 9B
along one gash
Lead deviation on adja-
3.1.10 10 10
cent teeth
Lead deviation in one
3.1.11 11 11A
axial pitch
Lead deviation in three
3.1.12 12 —
axial pitches
Adjacent deviation along
3.1.13 line of action (measured at Not applicable 13
the cutting edge)
Total deviation along line
3.1.14 of action (measured at the Not applicable 14
cutting edge)
Axial pitch deviation from
3.1.15 15 15
thread to thread
Axial pitch deviation in
3.1.16 any three axial pitches 16 16
over all threads
a
See Clause 5.
b
Select the composite test when the line of action test is used
5 Derivation of allowable values
5.1 General
Test 7 does not conform to a datum value and is not among the statements in Clause 5 concerning grade
relationships.
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ISO 4468:2020(E)
With the exception of Test 7, the datum from which all the values in Table 6 are derived is the value of
45 µm Test 14 Grade A modules 16 to 25. See 3.2 for the explanations of symbols used.
5.2 Tests 1-6, 9, 12, 13 and 14
For tests 1 to 6, 9, 12, 13 and 14, use Formula (1):
K = 45 K K K (1)
1 to 6, 9, 12, 13, 14 e m g
5.3 Test 7
For test 7, use Formula (2):
K = 80 K (2)
7 g
5.4 Test 9A
For test 9A, use Formula (3):
K = K / [2 × tan α] (3)
9A 9d h
5.5 Tests 10
For test 10, use Formula (4):
K = 45 K K K √K (4)
10 e m g t
5.6 Tests 8, 8A, 9B, 11, 11A, 12, 15 and 16
For tests 8, 8A, 9B, 11, 11A, 12, 15 and 16, use Formula (5):
K = 45 K K K K (5)
8, 8A, 9B, 11, 11A, 12, 15, 16 e m g t
Test 9B is only valid for quality Grades 4A, 3A and 2A.
Tests 8, 8A, 9B, 10, 11, 11A, 15 and 16 are only valid for the following:
a) 1-thread, all module ranges;
b) 2-threads, module range 0,5 ≤ m ≤ 16;
c) 3- and 4-threads, module range 0,5 ≤ m ≤ 6;
d) 5-, 6- and 7-threads, module range 0,5 ≤ m ≤ 3,5.
5.7 Oversize tolerances
When the hob outside diameter exceeds the size given in Annex A, the following will apply. The standard
tolerances shall be increased by a factor of one-half of the percent oversize.
For tests 4, 5, 6, 10, 11, 11A, 12, 13, 14, 15 and 16, use Formula (6):
K = K [(D -D)/D/2] + K (6)
4, 5, 6, 10, 11, 11A, 12, 13, 14, 15, 16 tol o tol
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ISO 4468:2020(E)
5.8 All tests
The value of the allowable deviations has been rounded to the nearest whole value after calculation.
The minimum value of allowable deviations is 2 < m.
Standard bores shall be finished straight and parallel within the tolerances given in Table 2 for 75 % of
each bearing length for Grades 4A, 3A, 2A, A and B hobs and 50 % for Grades C and D hobs.
A reference mandrel of nominal bore diameter shall pass through the bore as a check of alignment.
The tolerances on bore diameter are specified in Table 2.
Table 2 — Tolerance on bores
a
Tolerance
Grade Datum diameter
of hob mm
8 10 13 16 22 27 32 40 50 60 80
4A H3
3A H4
H3
2A
A H4 H5
B H5
C
H6
D
a
The tolerance shall be in accordance with ISO 286-2.
Table 3 — Ratio for test element and grade
Test Ratio of test element Ratio of grade
number
K
K
e g
4A 3A 2A A B C D
1 0,3
1,6 1,6 2,11
2 0,25
3 1,6 3,6 4,75
4 1,25
1,8
5 1,4 0,35 0,5 0,71 2,38
1,8
6 2,6 1
7 No relationship to test 14 1,25 2,31
8 0,5
4 5,28
8A 0,85
2
9 1,5
0,71 0,71 1 2 2,54
9A As by Table 4
a
The tolerance shall be in accordance with ISO 286-2.
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ISO 4468:2020(E)
Table 3 (continued)
Test Ratio of test element Ratio of grade
number
K
K
e g
4A 3A 2A A B C D
9B 0,8 — — — —
10 0,4
11 0,7
11A 0,8
12 1,3 0,35 0,5 0,71
1 2 4 5,28
13 0,4
14 1
15 0,45
16 0,8
a
The tolerance shall be in accordance with ISO 286-2.
The ratio for division of module s are defined in Table 4.
Table 4 — Ratio for division of module
Module range Ratio for module range Multiplication
m K factor
m
0,5 ≤ m ≤ 1 0,33
1,12
1 < m ≤ 2 0,37
1,12
2 < m ≤ 3,5 0,41
1,25
3,5 < m ≤ 6 0,51
1,25
6 < m ≤ 10 0,64
1,25
10 < m ≤ 16 0,8
1,25
16 < m ≤ 25 1
1,32
25 < m ≤ 40 1,32
The ratio for number of threads are defined in Table 5.
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ISO 4468:2020(E)
Table 5 — Ratio for number of threads
Number Ratio for number Multiplication
of threads of threads factor
K
t
1 1 1,25
2 1,25
1,25
3,4 1,56
1,25
5,6,7 1,95
The accuracy requirements are defined in Table 6.
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ISO 4468:2020(E)
10 © ISO 2020 – All rights reserved
Table 6 — Accuracy requirements
Allowable deviation
Test Pitch range
µm
Element Drawing Object of test
No module, m
Grade
(See the end of this table for the key to the drawings.) mm 4A 3A 2A A B C D
0,5 ≤ m ≤ 1 2 2 3 4 7 7 9
1 < m ≤ 2 2 2 4 5 8 8 11
2 < m ≤ 3,5 2 3 4 6 9 9 12
3,5 < m ≤ 6 2 3 5 7 11 11 15
1 Hub diameter Radial runout
6 < m ≤ 10 3 4 6 9 14 14 18
10 < m ≤ 16 4 5 8 11 17 17 23
16 < m ≤ 25 5 7 10 14 22 22 28
25 < m ≤ 40 6 9 13 18 29 29 38
0,5 ≤ m ≤ 1 2 2 3 4 6 6 8
1 < m ≤ 2 2 2 3 4 7 7 9
2 < m ≤ 3,5 2 2 3 5 7 7 10
3,5 < m ≤ 6 2 3 4 6 9 9 12
2 Hub face Axial runout
6 < m ≤ 10 3 4 5 7 12 12 15
10 < m ≤ 16 3 5 6 9 14 14 19
16 < m ≤ 25 4 6 8 11 18 18 24
25 < m ≤ 40 5 7 11 15 24 24 31
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ISO 4468:2020(E)
© ISO 2020 – All rights reserved 11
Table 6 (continued)
Allowable deviation
Test Pitch range
µm
Element Drawing Object of test
No module, m
Grade
(See the end of this table for the key to the drawings.) mm 4A 3A 2A A B C D
0,5 ≤ m ≤ 1 8 12 17 24 43 86 113
1 < m ≤ 2 9 13 19 27 48 96 127
2 < m ≤ 3,5 10 15 21 30 53 106 140
3,5 < m ≤ 6 13 18 26 37 66 132 174
Outside Radial runout of
3
diameter tips of teeth
6 < m ≤ 10 16 23 33 46 83 166 219
10 < m ≤ 16 20 29 41 58 104 207 274
16 < m ≤ 25 25 36 51 72 130 259 342
25 < m ≤ 40 33 48 67 95 171 342 451
0,5 ≤ m ≤ 1 6 9 13 19 33 33 44
1 < m ≤ 2 7 10 15 21 37 37 50
2 < m ≤ 3,5 8 12 16 23 42 42 55
Straightness and
3,5 < m ≤ 6 10 14 20 29 52 52 68
Cutting face of
4 radial alignment
gashes
6 < m ≤ 10 13 18 26 36 65 65 86
over cutting depth
10 < m ≤ 16 16 23 32 45 81 81 107
16 < m ≤ 25 20 28 40 56 101 101 134
25 < m ≤ 40 26 37 53 74 134 134 177
0,5 ≤ m ≤ 1 7 10 15 21 37 37 49
1 < m ≤ 2 8 12 17 23 42 42 55
2 < m ≤ 3,5 9 13 18 26 46 46 61
3,5 < m ≤ 6 11 16 23 32 58 58 76
Cutting face of
5 Adjacent spacing
gashes
6 < m ≤ 10 14 20 29 40 73 73 96
10 < m ≤ 16 18 25 36 50 91 91 120
16 < m ≤ 25 22 32 45 63 113 113 150
NOTE The numbers 1, 2, 3, etc. refer to the cutting teeth on the hob.
25 < m ≤ 40 29 42 59 83 150 150 198
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ISO 4468:2020(E)
12 © ISO 2020 – All rights reserved
Table 6 (continued)
Allowable deviation
Test Pitch range
µm
Element Drawing Object of test
No module, m
Grade
(See the end of this table for the key to the drawings.) mm 4A 3A 2A A B C D
0,5 ≤ m ≤ 1 14 19 27 39 69 69 92
1 < m ≤ 2 15 22 31 43 78 78 103
2 < m ≤ 3,5 17 24 34 48 86 86 114
3,5 < m ≤ 6 21 30 42 60 107 107 142
Cutting face of
6 Total spacing
gashes
6 < m ≤ 10 26 37 53 75 135 135 178
10 < m ≤ 16 33 47 66 94 168 168 223
16 < m ≤ 25 41 59 83 117 211 211 278
NOTE The numbers 1, 2, 3, etc. refer to the cutting teeth on the hob.
25 < m ≤ 40 54 77 110 154 278 278 368
Cutting face of Gash lead devia-
7 0,5 ≤ m ≤ 40 28 40 57 80 100 144 185
gashes tion per 100 mm
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ISO 4468:2020(E)
© ISO 2020 – All rights reserved 13
Table 6 (continued)
Allowable deviation
Test Pitch range
µm
Element Drawing Object of test
No module, m
Grade
(See the end of this table for the key to the drawings.) mm 4A 3A 2A A B C D
0,5 ≤ m ≤ 1 3 4 5 7 15 30 39
1 < m ≤ 2 3 4 6 8 17 33 44
2 < m ≤ 3,5 3 5 7 9 18 37 49
Tooth profile
3,5 < m ≤ 6 4 6 8 11 23 46 61
6 < m ≤ 10 5 7 10 14 29 58 76
1-thread
10 < m ≤ 16 6 9 13 18 36 72 95
16 < m ≤ 25 8 11 16 23 45 90 119
25 < m ≤ 40 10 15 21 30 59 119 157
0,5 ≤ m ≤ 1 3 5 7 9 19 37 49
1 < m ≤ 2 4 5 7 10 21 42 55
2 < m ≤ 3,5 4 6 8 12 23 46 61
3,5 < m ≤ 6 5 7 10 14 29 57 76
8 Tooth 2-threads
6 < m ≤ 10 6 9 13 18 36 72 95
10 < m ≤ 16 8 11 16 23 45 90 119
16 < m ≤ 25 — — — — — — —
25 < m ≤ 40 — — — — — — —
0,5 ≤ m ≤ 1 4 6 8 12 23 46 61
1 < m ≤ 2 5 6 9 13 26 52 69
2 < m ≤ 3,5 5 7 10 14 29 58 76
3,5 < m ≤ 6 6 9 13 18 36 72 95
3-, 4-threads
6 < m ≤ 10 — — — — — — —
10 < m ≤ 16 — — — — — — —
16 < m ≤ 25 — — — — — — —
25 < m ≤ 40 — — — — — — —
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ISO 4468:2020(E)
14 © ISO 2020 – All rights reserved
Table 6 (continued)
Allowable deviation
Test Pitch range
µm
Element Drawing Object of test
No module, m
Grade
(See the end of this table for the key to the drawings.) mm 4A 3A 2A A B C D
0,5 ≤ m ≤ 1 5 7 10 14 29 58 76
1 < m ≤ 2 6 8 12 16 32 65 86
2 < m ≤ 3,5 6 9 13 18 36 72 95
3,5 < m ≤ 6 — — — — — — —
8 5-, 6-, 7-threads
6 < m ≤ 10 — — — — — — —
10 < m ≤ 16 — — — — — — —
16 < m ≤ 25 — — — — — — —
25 < m ≤ 40 — — — — — — —
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ISO 4468:2020(E)
© ISO 2020 – All rights reserved 15
Table 6 (continued)
Allowable deviation
Test Pitch range
µm
Element Drawing Object of test
No module, m
Grade
(See the end of this table for the key to the drawings.) mm 4A 3A 2A A B C D
0,5 ≤ m ≤ 1 4 6 9 13 25 50 67
1 < m ≤ 2 5 7 10 14 28 57 75
2 < m ≤ 3,5 5 8 11 16 31 63 83
Tooth profile
(when line of ac-
3,5 < m ≤ 6 7 10 14 20 39 78 103
tion test is used)
6 < m ≤ 10 9 12 17 24 49 98 129
1-thread
10 < m ≤ 16 11 15 22 31 61 112 162
16 < m ≤ 25 13 19 27 38 77 153 202
25 < m ≤ 40 18 25 36 50 101 202 267
0,5 ≤ m ≤ 1 6 8 11 16 32 63 83
1 < m ≤ 2 6 9 13 18 35 71 93
2 < m ≤ 3,5 7 10 14 20 39 78 104
3,5 < m ≤ 6 9 12 17 24 49 98 129
8A Tooth 2-threads
6 < m ≤ 10 11 15 22 31 61 122 162
10 < m ≤ 16 13 19 27 38 77 153 202
16 < m ≤ 25 — — — — — — —
25 < m ≤ 40 — — — — — — —
0,5 ≤ m ≤ 1 7 10 14 20 39 79 104
1 < m ≤ 2 8 11 16 22 44 88 117
2 < m ≤ 3,5 9 12 17 24 49 98 129
3,5 < m ≤ 6 11 15 22 30 61 122 161
3-, 4-threads
6 < m ≤ 10 — — — — — — —
10 < m ≤ 16 — — — — — — —
16 < m ≤ 25 — — — — — — —
25 < m ≤ 40 — — — — — — —
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ISO 4468:2020(E)
16 © ISO 2020 – All rights reserved
Table 6 (continued)
Allowable deviation
Test Pitch range
µm
Element Drawing Object of test
No module, m
Grade
(See the end of this table for the key to the drawings.) mm 4A 3A 2A A B C D
0,5 ≤ m ≤ 1 9 12 17 25 49 98 130
1 < m ≤ 2 10 14 20 28 55 110 146
2 < m ≤ 3,5 11 15 22 31 61 122 161
3,5 < m ≤ 6 — — — — — — —
8A 5-, 6-, 7-threads
6 < m ≤ 10 — — — — — — —
10 < m ≤ 16 — — — — — — —
16 < m ≤ 25 — — — — — — —
25 < m ≤ 40 — — — — — — —
0,5 ≤ m ≤ 1 16 16 22 22 45 45 57
1 < m ≤ 2 18 18 25 25 50 50 63
2 < m ≤ 3,5 20 20 28 28 55 55 70
Normal tooth
3,5 < m ≤ 6 24 24 34 34 69 69 87
9 Tooth thickness
6 < m ≤ 10 31 31 43 43 86 86 110
(negative only)
10 < m ≤ 16 38 38 54 54 108 108 137
16 < m ≤ 25 48 48 68 68 135 135 171
25 < m ≤ 40 63 63 89 89 178 178 226
0,5 ≤ m ≤ 1
1 < m ≤ 2
2 < m ≤ 3,5
3,5 < m ≤ 6
Addendum Deviations from test 9 divided by
9A Tooth
(positive only) 2*tan (pressure angle)
6 < m ≤ 10
10 < m ≤ 16
16 < m ≤ 25
25 < m ≤ 40
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ISO 4468:2020(E)
© ISO 2020 – All rights reserved 17
Table 6 (continued)
Allowable deviation
Test Pitch range
µm
Element Drawing Object of test
No module, m
Grade
(See the end of this table for the key to the drawings.) mm 4A 3A 2A A B C D
0,5 ≤ m ≤ 1 4 6 8
1 < m ≤ 2 5 7 9
Difference be-
tween maximum 2 < m ≤ 3,5 5 7 10
and minimum
3,5 < m ≤ 6 6 9 13
normal tooth
thickness along 6 < m ≤ 10 8 12 16
one gash
10 < m ≤ 16 10 14 20
1-thread
16 < m ≤ 25 13 18 26
25 < m ≤ 40 17 24 34
0,5 ≤ m ≤ 1 5 7 11
1 < m ≤ 2 6 8 12
2 < m ≤ 3,5 6 9 13
3,5 < m ≤ 6 8 11 16
Test 9B is only valid for
9B Tooth 2-threads
quality grade 4A, 3A and 2A.
6 < m ≤ 10 10 14 20
10 < m ≤ 16 13 18 26
16 < m ≤ 25 — — —
25 < m ≤ 40 — — —
0,5 ≤ m ≤ 1 6 9 13
1 < m ≤ 2 7 10 15
2 < m ≤ 3,5 8 12 16
3,5 < m ≤ 6 10 14 20
3-, 4-threads
6 < m ≤ 10 — — —
10 < m ≤ 16 — — —
16 < m ≤ 25 — — —
25 < m ≤ 40 — — —
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ISO 4468:2020(E)
18 © ISO 2020 – All rights reserved
Table 6 (continued)
Allowable deviation
Test Pitch range
µm
Element Drawing Object of test
No module, m
Grade
(See the end of this table for the key to the drawings.) mm 4A 3A 2A A B C D
0,5 ≤ m ≤ 1 8 12 16
1 < m ≤ 2 9 13 18
2 < m ≤ 3,5 10 14 20
3,5 < m ≤ 6 — — —
9B 5-, 6-, 7-threads
6 < m ≤ 10 — — —
10 < m ≤ 16 — — —
16 < m ≤ 25 — — —
25 < m ≤ 40 — — —
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ISO 4468:2020(E)
© ISO 2020 – All rights reserved 19
Table 6 (continued)
Allowable deviation
Test Pitch range
µm
Element Drawing Object of test
No module, m
Grade
(See the end of this table for the key to the drawings.) mm 4A 3A 2A A B C D
0,5 ≤ m ≤ 1 2 3 4 6 12 24 31
1 < m ≤ 2 2 3 5 7 13 27 35
2 < m ≤ 3,5 3 4 5 7 15 30 39
Lead deviation on
3,5 < m ≤ 6 3 5 7 9 18 37 48
adjacent teeth
6 < m ≤ 10 4 6 8
...
SLOVENSKI STANDARD
SIST ISO 4468:2020
01-november-2020
Polžasta frezala - Zahteve po točnosti
Gear hobs - Accuracy requirements
Fraises-mères - Exigences d'exactitude
Ta slovenski standard je istoveten z: ISO 4468:2020
ICS:
21.200 Gonila Gears
SIST ISO 4468:2020 en,fr,de
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.
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SIST ISO 4468:2020
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SIST ISO 4468:2020
INTERNATIONAL ISO
STANDARD 4468
Third edition
2020-07
Gear hobs — Accuracy requirements
Fraises-mères — Exigences d'exactitude
Reference number
ISO 4468:2020(E)
©
ISO 2020
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SIST ISO 4468:2020
ISO 4468:2020(E)
COPYRIGHT PROTECTED DOCUMENT
© ISO 2020
All rights reserved. Unless otherwise specified, or required in the context of its implementation, no part of this publication may
be reproduced or utilized otherwise in any form or by any means, electronic or mechanical, including photocopying, or posting
on the internet or an intranet, without prior written permission. Permission can be requested from either ISO at the address
below or ISO’s member body in the country of the requester.
ISO copyright office
CP 401 • Ch. de Blandonnet 8
CH-1214 Vernier, Geneva
Phone: +41 22 749 01 11
Email: copyright@iso.org
Website: www.iso.org
Published in Switzerland
ii © ISO 2020 – All rights reserved
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SIST ISO 4468:2020
ISO 4468:2020(E)
Contents Page
Foreword .iv
1 Scope . 1
2 Normative references . 1
3 Terms, definitions and symbols . 2
3.1 Terms and definitions . 2
3.2 Symbols . 4
4 Allowable deviations . 4
5 Derivation of allowable values . 5
5.1 General . 5
5.2 Tests 1-6, 9, 12, 13 and 14 . 6
5.3 Test 7. 6
5.4 Test 9A . 6
5.5 Tests 10 . 6
5.6 Tests 8, 8A, 9B, 11, 11A, 12, 15 and 16 . 6
5.7 Oversize tolerances . 6
5.8 All tests . 7
Annex A (normative) Nominal dimensions of general-purpose single-start solid
(monobloc) gear hobs with axial keyway or tenon drive of 0,5 to 40 module .30
Bibliography .39
© ISO 2020 – All rights reserved iii
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SIST ISO 4468:2020
ISO 4468:2020(E)
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.
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
different types of ISO documents should be noted. This document was drafted 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 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. Details of
any patent rights identified during the development of 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 information given for the convenience of users and does not
constitute an endorsement.
For an explanation of the voluntary nature of standards, the meaning of ISO specific terms and
expressions related to conformity assessment, as well as information about ISO's adherence to the
World Trade Organization (WTO) principles in the Technical Barriers to Trade (TBT), see www .iso .org/
iso/ foreword .html.
This document was prepared by Technical Committee ISO/TC 60, Gears, Subcommittee SC 1,
Nomenclature and wormgearing.
This third edition cancels and replaces the second edition (ISO 4468:2009), which has been technically
revised. It also incorporates the Technical Corrigendum ISO 4468:2009/Cor 1:2009.
The main changes compared to the previous edition are as follows:
— oversize tolerances: when the hob outside diameter exceeds the recommended size given in
ISO 2490, the standard tolerances shall be increased by a factor of one-half of the percent oversize;
— hob sizes: the standard hob sizes from ISO 2490 were added as Annex A.
Any feedback or questions on this document should be directed to the user’s national standards body. A
complete listing of these bodies can be found at www .iso .org/ members .html.
iv © ISO 2020 – All rights reserved
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SIST ISO 4468:2020
INTERNATIONAL STANDARD ISO 4468:2020(E)
Gear hobs — Accuracy requirements
1 Scope
This document specifies requirements for the accuracy of general-purpose hobs of 0,5 module to 40
module.
These hobs are intended for producing gears which conform to ISO 53 and ISO 54.
This document applies to hobs for spur and helical gears. It applies to solid (monobloc) and inserted
blade hobs.
The elemental features of hobs are graded according to accuracy, as follows:
— Grade 4A;
— Grade 3A;
— Grade 2A;
— Grade A;
— Grade B;
— Grade C;
— Grade D.
Grade 4A is the highest order of precision.
In addition to the elemental tests for hobs, this document gives permitted tolerances for composite
tests that are taken along the cutting edges on the line of action. The two groups of tests are not
equivalent and one can choose between one or the other. If there was no previous agreement, the hob is
regarded as belonging to the precision class specified if it satisfies one or the other of the two methods
of inspection.
NOTE The tolerances in this document were determined for gear hobs whose dimensions conform to
ISO 2490, but with certain precautions they can be applied to hobs not specified in this document.
2 Normative references
The following documents are referred to in the text in such a way that some or all of their content
constitutes requirements of this document. For dated references, only the edition cited applies. For
undated references, the latest edition of the referenced document (including any amendments) applies.
ISO 286-2, Geometrical product specifications (GPS) — ISO code system for tolerances on linear sizes —
Part 2: Tables of standard tolerance classes and limit deviations for holes and shafts
ISO 1122-1, Vocabulary of gear terms — Part 1: Definitions related to geometry
ISO 2768-1, General tolerances — Part 1: Tolerances for linear and angular dimensions without individual
tolerance indications
© ISO 2020 – All rights reserved 1
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SIST ISO 4468:2020
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3 Terms, definitions and symbols
3.1 Terms and definitions
For the purposes of this document, the terms and definitions given in ISO 1122-1 apply.
ISO and IEC maintain terminological databases for use in standardization at the following addresses:
— ISO Online browsing platform: available at https:// www .iso .org/ obp
— IEC Electropedia: available at http:// www .electropedia .org/
3.1.1
radial runout of hub diameter
total deviation in radial distance of the hub periphery from the axis
3.1.2
axial runout of hub face
total axial deviation of the hub face from a true plane of rotation
3.1.3
radial runout of tips of teeth
total deviation in the radial distance from the axis to the tips of the hob teeth
3.1.4
straightness and radial alignment over cutting depth
angular relationship between the tooth face and a radial line intersecting the tooth face at the hob
outside diameter, measured in a plane perpendicular to the axis
3.1.5
adjacent spacing of cutting face of gashes
maximum deviation between any two consecutive cutting face measurements
3.1.6
total spacing of cutting face of gashes
maximum deviation between any two cutting face measurements
3.1.7
gash lead deviation per 100 mm
maximum deviation as the probe contacts the tooth faces within the axial region of the gash
Note 1 to entry: Allowable values for deviations are given per 100 mm of cutting face width.
3.1.8
tooth profile deviation
maximum deviation of the portion of the hob tooth that generates an unmodified involute profile
3.1.9
tooth thickness
normal tooth thickness difference of the actual and reference datum at the reference cylinder
Note 1 to entry: Tooth thickness is negative only.
3.1.9.1
addendum
radial distance between the top of the hob tooth and the reference cylinder.
2 © ISO 2020 – All rights reserved
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SIST ISO 4468:2020
ISO 4468:2020(E)
3.1.9.2
tooth thickness difference along one gash
difference between the maximum and minimum nominal tooth thickness (3.1.9) along one gash at the
reference cylinder
Note 1 to entry: Test 9B is used for tooth thickness difference along one gash. This test is only valid for quality
Grades 4A, 3A and 2A (see Table 6).
3.1.10
lead deviation on adjacent teeth
maximum lead deviation between any two consecutive teeth
3.1.11
lead deviation in one axial pitch
maximum deviation between any two teeth within any group of consecutive teeth contained in one
axial pitch
Note 1 to entry: The number of teeth in one axial pitch is the number of teeth encountered by the measurement
probe as it moves parallel to the reference axis during lead testing for a distance of one axial pitch of the hob.
Note 2 to entry: Hobs having one thread:
Measuring distance = one axial pitch = one revolution
Hobs having two threads:
Measuring distance = one axial pitch = 1/2 revolution
Hobs having three threads:
Measuring distance = one axial pitch = 1/3 revolution, etc.
Note 3 to entry: The number of teeth is determined by the number of gashes, the number of threads and, in the
case of helical gash hobs, the gash lead.
Note 4 to entry: Test 11A is used for lead deviation in one axial pitch when the line of action test is used.
3.1.12
lead deviation in three axial pitches
maximum lead deviation between any two teeth contained in three axial pitches
Note 1 to entry: The number of teeth in three distance of three axial pitches of the hob axial pitches is that number
of teeth encountered by the measurement probe as it moves parallel to the reference axis during lead testing for
a distance of three axial pitches of the hob.
Note 2 to entry: The number of teeth is determined by the number of gashes, the number of threads and, in the
case of helical gash hobs, the gash lead.
3.1.13
adjacent deviation along line of action
maximum deviation between any two consecutive teeth of a given line of action test
Note 1 to entry: Adjacent hob line of action allowable deviation can be applied to adjacent line of action test
results in those cases where the hob has been specified to be manufactured with involute helicoid geometry.
3.1.14
total deviation along line of action
total maximum deviation between any two teeth of a given line of action test
© ISO 2020 – All rights reserved 3
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3.1.15
axial pitch deviation from thread to thread
maximum axial pitch deviation between any two consecutive teeth contained within two gashes
Note 1 to entry: For an odd number of threads, the angle between the gashes is approximately 90°. For an even
number of threads, it is approximately 120°.
3.1.16
axial pitch deviation in any three axial pitches over all threads
maximum axial pitch deviation over any three adjacent teeth contained within two gashes
Note 1 to entry: For an odd number of threads, the angle between the gashes is approximately 90°. For an even
number of threads, it is approximately 120°.
3.2 Symbols
D hob outside diameter given by Annex A for the given module
D hob oversize outside diameter
o
K ratio for test element (see Table 3)
e
K ratio for division of module (see Table 4)
m
K ratio for grade (see Table 3)
g
K ratio for number of threads (see Table 5)
t
K standard tolerance for the test
tol
K calculated value for test i
i
K deviation test 9
9d
α hob normal pressure angle
h
4 Allowable deviations
Hobs shall conform to the requirements of Tables 2 and 4, as appropriate. The hob sizes shall be in
accordance with Annex A.
When prior agreement between the hob manufacturer and purchaser specifies measurement of hobs,
the manufacturer should select:
— the measurement method to be used from among the applicable methods described in this document
and summarized in Table 1;
— the piece of measurement equipment to be used by the selected measurement method, provided it
is in proper calibration;
— the individual teeth to be measured, as long as they are approximately equally spaced.
No particular method of measurement or documentation is considered mandatory. When applications
require measurements beyond those recommended in this document, it is recommended to negotiate
special measurement methods prior to manufacturing the hob.
4 © ISO 2020 – All rights reserved
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Table 1 — Reference for measurement methods
a
Test number
Test method
Test description
definition b
Elemental test Composite test
Radial runout of hub
3.1.1 1 1
diameter
3.1.2 Axial runout of hub face 2 2
Radial runout of tips of
3.1.3 3 3
teeth
Straightness and radial
3.1.4 alignment over cutting 4 4
depth
Adjacent spacing of cutting
3.1.5 5 5
face of gashes
Total spacing of cutting
3.1.6 6 6
face of gashes
Gash lead deviation per
3.1.7 7 7
100 mm
3.1.8 Tooth profile deviation 8 8A
3.1.9 Tooth thickness 9 9
Addendum difference
of values related to the
3.1.9.1 9A 9A
designed normal tooth
thickness
Tooth thickness difference
3.1.9.2 9B 9B
along one gash
Lead deviation on adja-
3.1.10 10 10
cent teeth
Lead deviation in one
3.1.11 11 11A
axial pitch
Lead deviation in three
3.1.12 12 —
axial pitches
Adjacent deviation along
3.1.13 line of action (measured at Not applicable 13
the cutting edge)
Total deviation along line
3.1.14 of action (measured at the Not applicable 14
cutting edge)
Axial pitch deviation from
3.1.15 15 15
thread to thread
Axial pitch deviation in
3.1.16 any three axial pitches 16 16
over all threads
a
See Clause 5.
b
Select the composite test when the line of action test is used
5 Derivation of allowable values
5.1 General
Test 7 does not conform to a datum value and is not among the statements in Clause 5 concerning grade
relationships.
© ISO 2020 – All rights reserved 5
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SIST ISO 4468:2020
ISO 4468:2020(E)
With the exception of Test 7, the datum from which all the values in Table 6 are derived is the value of
45 µm Test 14 Grade A modules 16 to 25. See 3.2 for the explanations of symbols used.
5.2 Tests 1-6, 9, 12, 13 and 14
For tests 1 to 6, 9, 12, 13 and 14, use Formula (1):
K = 45 K K K (1)
1 to 6, 9, 12, 13, 14 e m g
5.3 Test 7
For test 7, use Formula (2):
K = 80 K (2)
7 g
5.4 Test 9A
For test 9A, use Formula (3):
K = K / [2 × tan α] (3)
9A 9d h
5.5 Tests 10
For test 10, use Formula (4):
K = 45 K K K √K (4)
10 e m g t
5.6 Tests 8, 8A, 9B, 11, 11A, 12, 15 and 16
For tests 8, 8A, 9B, 11, 11A, 12, 15 and 16, use Formula (5):
K = 45 K K K K (5)
8, 8A, 9B, 11, 11A, 12, 15, 16 e m g t
Test 9B is only valid for quality Grades 4A, 3A and 2A.
Tests 8, 8A, 9B, 10, 11, 11A, 15 and 16 are only valid for the following:
a) 1-thread, all module ranges;
b) 2-threads, module range 0,5 ≤ m ≤ 16;
c) 3- and 4-threads, module range 0,5 ≤ m ≤ 6;
d) 5-, 6- and 7-threads, module range 0,5 ≤ m ≤ 3,5.
5.7 Oversize tolerances
When the hob outside diameter exceeds the size given in Annex A, the following will apply. The standard
tolerances shall be increased by a factor of one-half of the percent oversize.
For tests 4, 5, 6, 10, 11, 11A, 12, 13, 14, 15 and 16, use Formula (6):
K = K [(D -D)/D/2] + K (6)
4, 5, 6, 10, 11, 11A, 12, 13, 14, 15, 16 tol o tol
6 © ISO 2020 – All rights reserved
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5.8 All tests
The value of the allowable deviations has been rounded to the nearest whole value after calculation.
The minimum value of allowable deviations is 2 < m.
Standard bores shall be finished straight and parallel within the tolerances given in Table 2 for 75 % of
each bearing length for Grades 4A, 3A, 2A, A and B hobs and 50 % for Grades C and D hobs.
A reference mandrel of nominal bore diameter shall pass through the bore as a check of alignment.
The tolerances on bore diameter are specified in Table 2.
Table 2 — Tolerance on bores
a
Tolerance
Grade Datum diameter
of hob mm
8 10 13 16 22 27 32 40 50 60 80
4A H3
3A H4
H3
2A
A H4 H5
B H5
C
H6
D
a
The tolerance shall be in accordance with ISO 286-2.
Table 3 — Ratio for test element and grade
Test Ratio of test element Ratio of grade
number
K
K
e g
4A 3A 2A A B C D
1 0,3
1,6 1,6 2,11
2 0,25
3 1,6 3,6 4,75
4 1,25
1,8
5 1,4 0,35 0,5 0,71 2,38
1,8
6 2,6 1
7 No relationship to test 14 1,25 2,31
8 0,5
4 5,28
8A 0,85
2
9 1,5
0,71 0,71 1 2 2,54
9A As by Table 4
a
The tolerance shall be in accordance with ISO 286-2.
© ISO 2020 – All rights reserved 7
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SIST ISO 4468:2020
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Table 3 (continued)
Test Ratio of test element Ratio of grade
number
K
K
e g
4A 3A 2A A B C D
9B 0,8 — — — —
10 0,4
11 0,7
11A 0,8
12 1,3 0,35 0,5 0,71
1 2 4 5,28
13 0,4
14 1
15 0,45
16 0,8
a
The tolerance shall be in accordance with ISO 286-2.
The ratio for division of module s are defined in Table 4.
Table 4 — Ratio for division of module
Module range Ratio for module range Multiplication
m K factor
m
0,5 ≤ m ≤ 1 0,33
1,12
1 < m ≤ 2 0,37
1,12
2 < m ≤ 3,5 0,41
1,25
3,5 < m ≤ 6 0,51
1,25
6 < m ≤ 10 0,64
1,25
10 < m ≤ 16 0,8
1,25
16 < m ≤ 25 1
1,32
25 < m ≤ 40 1,32
The ratio for number of threads are defined in Table 5.
8 © ISO 2020 – All rights reserved
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SIST ISO 4468:2020
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Table 5 — Ratio for number of threads
Number Ratio for number Multiplication
of threads of threads factor
K
t
1 1 1,25
2 1,25
1,25
3,4 1,56
1,25
5,6,7 1,95
The accuracy requirements are defined in Table 6.
© ISO 2020 – All rights reserved 9
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SIST ISO 4468:2020
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10 © ISO 2020 – All rights reserved
Table 6 — Accuracy requirements
Allowable deviation
Test Pitch range
µm
Element Drawing Object of test
No module, m
Grade
(See the end of this table for the key to the drawings.) mm 4A 3A 2A A B C D
0,5 ≤ m ≤ 1 2 2 3 4 7 7 9
1 < m ≤ 2 2 2 4 5 8 8 11
2 < m ≤ 3,5 2 3 4 6 9 9 12
3,5 < m ≤ 6 2 3 5 7 11 11 15
1 Hub diameter Radial runout
6 < m ≤ 10 3 4 6 9 14 14 18
10 < m ≤ 16 4 5 8 11 17 17 23
16 < m ≤ 25 5 7 10 14 22 22 28
25 < m ≤ 40 6 9 13 18 29 29 38
0,5 ≤ m ≤ 1 2 2 3 4 6 6 8
1 < m ≤ 2 2 2 3 4 7 7 9
2 < m ≤ 3,5 2 2 3 5 7 7 10
3,5 < m ≤ 6 2 3 4 6 9 9 12
2 Hub face Axial runout
6 < m ≤ 10 3 4 5 7 12 12 15
10 < m ≤ 16 3 5 6 9 14 14 19
16 < m ≤ 25 4 6 8 11 18 18 24
25 < m ≤ 40 5 7 11 15 24 24 31
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SIST ISO 4468:2020
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© ISO 2020 – All rights reserved 11
Table 6 (continued)
Allowable deviation
Test Pitch range
µm
Element Drawing Object of test
No module, m
Grade
(See the end of this table for the key to the drawings.) mm 4A 3A 2A A B C D
0,5 ≤ m ≤ 1 8 12 17 24 43 86 113
1 < m ≤ 2 9 13 19 27 48 96 127
2 < m ≤ 3,5 10 15 21 30 53 106 140
3,5 < m ≤ 6 13 18 26 37 66 132 174
Outside Radial runout of
3
diameter tips of teeth
6 < m ≤ 10 16 23 33 46 83 166 219
10 < m ≤ 16 20 29 41 58 104 207 274
16 < m ≤ 25 25 36 51 72 130 259 342
25 < m ≤ 40 33 48 67 95 171 342 451
0,5 ≤ m ≤ 1 6 9 13 19 33 33 44
1 < m ≤ 2 7 10 15 21 37 37 50
2 < m ≤ 3,5 8 12 16 23 42 42 55
Straightness and
3,5 < m ≤ 6 10 14 20 29 52 52 68
Cutting face of
4 radial alignment
gashes
6 < m ≤ 10 13 18 26 36 65 65 86
over cutting depth
10 < m ≤ 16 16 23 32 45 81 81 107
16 < m ≤ 25 20 28 40 56 101 101 134
25 < m ≤ 40 26 37 53 74 134 134 177
0,5 ≤ m ≤ 1 7 10 15 21 37 37 49
1 < m ≤ 2 8 12 17 23 42 42 55
2 < m ≤ 3,5 9 13 18 26 46 46 61
3,5 < m ≤ 6 11 16 23 32 58 58 76
Cutting face of
5 Adjacent spacing
gashes
6 < m ≤ 10 14 20 29 40 73 73 96
10 < m ≤ 16 18 25 36 50 91 91 120
16 < m ≤ 25 22 32 45 63 113 113 150
NOTE The numbers 1, 2, 3, etc. refer to the cutting teeth on the hob.
25 < m ≤ 40 29 42 59 83 150 150 198
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12 © ISO 2020 – All rights reserved
Table 6 (continued)
Allowable deviation
Test Pitch range
µm
Element Drawing Object of test
No module, m
Grade
(See the end of this table for the key to the drawings.) mm 4A 3A 2A A B C D
0,5 ≤ m ≤ 1 14 19 27 39 69 69 92
1 < m ≤ 2 15 22 31 43 78 78 103
2 < m ≤ 3,5 17 24 34 48 86 86 114
3,5 < m ≤ 6 21 30 42 60 107 107 142
Cutting face of
6 Total spacing
gashes
6 < m ≤ 10 26 37 53 75 135 135 178
10 < m ≤ 16 33 47 66 94 168 168 223
16 < m ≤ 25 41 59 83 117 211 211 278
NOTE The numbers 1, 2, 3, etc. refer to the cutting teeth on the hob.
25 < m ≤ 40 54 77 110 154 278 278 368
Cutting face of Gash lead devia-
7 0,5 ≤ m ≤ 40 28 40 57 80 100 144 185
gashes tion per 100 mm
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© ISO 2020 – All rights reserved 13
Table 6 (continued)
Allowable deviation
Test Pitch range
µm
Element Drawing Object of test
No module, m
Grade
(See the end of this table for the key to the drawings.) mm 4A 3A 2A A B C D
0,5 ≤ m ≤ 1 3 4 5 7 15 30 39
1 < m ≤ 2 3 4 6 8 17 33 44
2 < m ≤ 3,5 3 5 7 9 18 37 49
Tooth profile
3,5 < m ≤ 6 4 6 8 11 23 46 61
6 < m ≤ 10 5 7 10 14 29 58 76
1-thread
10 < m ≤ 16 6 9 13 18 36 72 95
16 < m ≤ 25 8 11 16 23 45 90 119
25 < m ≤ 40 10 15 21 30 59 119 157
0,5 ≤ m ≤ 1 3 5 7 9 19 37 49
1 < m ≤ 2 4 5 7 10 21 42 55
2 < m ≤ 3,5 4 6 8 12 23 46 61
3,5 < m ≤ 6 5 7 10 14 29 57 76
8 Tooth 2-threads
6 < m ≤ 10 6 9 13 18 36 72 95
10 < m ≤ 16 8 11 16 23 45 90 119
16 < m ≤ 25 — — — — — — —
25 < m ≤ 40 — — — — — — —
0,5 ≤ m ≤ 1 4 6 8 12 23 46 61
1 < m ≤ 2 5 6 9 13 26 52 69
2 < m ≤ 3,5 5 7 10 14 29 58 76
3,5 < m ≤ 6 6 9 13 18 36 72 95
3-, 4-threads
6 < m ≤ 10 — — — — — — —
10 < m ≤ 16 — — — — — — —
16 < m ≤ 25 — — — — — — —
25 < m ≤ 40 — — — — — — —
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SIST ISO 4468:2020
ISO 4468:2020(E)
14 © ISO 2020 – All rights reserved
Table 6 (continued)
Allowable deviation
Test Pitch range
µm
Element Drawing Object of test
No module, m
Grade
(See the end of this table for the key to the drawings.) mm 4A 3A 2A A B C D
0,5 ≤ m ≤ 1 5 7 10 14 29 58 76
1 < m ≤ 2 6 8 12 16 32 65 86
2 < m ≤ 3,5 6 9 13 18 36 72 95
3,5 < m ≤ 6 — — — — — — —
8 5-, 6-, 7-threads
6 < m ≤ 10 — — — — — — —
10 < m ≤ 16 — — — — — — —
16 < m ≤ 25 — — — — — — —
25 < m ≤ 40 — — — — — — —
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SIST ISO 4468:2020
ISO 4468:2020(E)
© ISO 2020 – All rights reserved 15
Table 6 (continued)
Allowable deviation
Test Pitch range
µm
Element Drawing Object of test
No module, m
Grade
(See the end of this table for the key to the drawings.) mm 4A 3A 2A A B C D
0,5 ≤ m ≤ 1 4 6 9 13 25 50 67
1 < m ≤ 2 5 7 10 14 28 57 75
2 < m ≤ 3,5 5 8 11 16 31 63 83
Tooth profile
(when line of ac-
3,5 < m ≤ 6 7 10 14 20 39 78 103
tion test is used)
6 < m ≤ 10 9 12 17 24 49 98 129
1-thread
10 < m ≤ 16 11 15 22 31 61 112 162
16 < m ≤ 25 13 19 27 38 77 153 202
25 < m ≤ 40 18 25 36 50 101 202 267
0,5 ≤ m ≤ 1 6 8 11 16 32 63 83
1 < m ≤ 2 6 9 13 18 35 71 93
2 < m ≤ 3,5 7 10 14 20 39 78 104
3,5 < m ≤ 6 9 12 17 24 49 98 129
8A Tooth 2-threads
6 < m ≤ 10 11 15 22 31 61 122 162
10 < m ≤ 16 13 19 27 38 77 153 202
16 < m ≤ 25 — — — — — — —
25 < m ≤ 40 — — — — — — —
0,5 ≤ m ≤ 1 7 10 14 20 39 79 104
1 < m ≤ 2 8 11 16 22 44 88 117
2 < m ≤ 3,5 9 12 17 24 49 98 129
3,5 < m ≤ 6 11 15 22 30 61 122 161
3-, 4-threads
6 < m ≤ 10 — — — — — — —
10 < m ≤ 16 — — — — — — —
16 < m ≤ 25 — — — — — — —
25 < m ≤ 40 — — — — — — —
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SIST ISO 4468:2020
ISO 4468:2020(E)
16 © ISO 2020 – All rights reserved
Table 6 (continued)
Allowable deviation
Test Pitch range
µm
Element Drawing Object of test
No module, m
Grade
(See the end of this table for the key to the drawings.) mm 4A 3A 2A A B C D
0,5 ≤ m ≤ 1 9 12 17 25 49 98 130
1 < m ≤ 2 10 14 20 28 55 110 146
2 < m ≤ 3,5 11 15 22 31 61 122 161
3,5 < m ≤ 6 — — — — — — —
8A 5-, 6-, 7-threads
6 < m ≤ 10 — — — — — — —
10 < m ≤ 16 — — — — — — —
16 < m ≤ 25 — — — — — — —
25 < m ≤ 40 — — — — — — —
0,5 ≤ m ≤ 1 16 16 22 22 45 45 57
1 < m ≤ 2 18 18 25 25 50 50 63
2 < m ≤ 3,5 20 20 28 28 55 55 70
Normal tooth
3,5 < m ≤ 6 24 24 34 34 69 69 87
9 Tooth thickness
6 < m ≤ 10 31 31 43 43 86 86 110
(negative only)
10 < m ≤ 16 38 38 54 54 108 108 137
16 < m ≤ 25 48 48 68 68 135 135 171
25 < m ≤ 40 63 63 89 89 178 178 226
0,5 ≤ m ≤ 1
1 < m ≤ 2
2 < m ≤ 3,5
3,5 < m ≤ 6
Addendum Deviations from test 9 divided by
9A Tooth
(positive only) 2*tan (pressure angle)
6 < m ≤ 10
10 < m ≤ 16
16 < m ≤ 25
25 < m ≤ 40
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SIST ISO 4468:2020
ISO 4468:2020(E)
© ISO 2020 – All rights reserved 17
Table 6 (continued)
Allowable deviation
Test Pitch range
µm
Element Drawing Object of test
No module, m
Grade
(See the end of this table for the key to the drawings.) mm 4A 3A 2A A B C D
0,5 ≤ m ≤ 1 4 6 8
1 < m ≤ 2 5 7 9
Difference be-
tween maximum 2 < m ≤ 3,5 5 7 10
and minimum
3,5 < m ≤ 6 6 9 13
normal tooth
thickness along 6 < m ≤ 10 8 12 16
one gash
10 < m ≤ 16 10 14 20
1-thread
16 < m ≤ 25 13 18 26
25 < m ≤ 40 17 24 34
0,5 ≤ m ≤ 1 5 7 11
1 < m ≤ 2 6 8 12
2 < m ≤ 3,5 6 9 13
3,5 < m ≤ 6 8 11 16
Test 9B is only valid for
9B Tooth 2-threads
quality grade 4A, 3A and 2A.
6 < m ≤ 10 10 14 20
10 < m ≤ 16 13 18 26
16 < m ≤ 25 — — —
25 < m ≤ 40 — — —
0,5 ≤ m ≤ 1 6 9 13
1 < m ≤ 2 7 10 15
2 < m ≤ 3,5 8 12 16
3,5 < m ≤ 6 10 14 20
3-, 4-threads
6 < m ≤ 10 — — —
10 < m ≤ 16 — — —
16 < m ≤ 25 — — —
25 < m ≤ 40 — — —
---------------------- Pa
...
FINAL
INTERNATIONAL ISO/FDIS
DRAFT
STANDARD 4468
ISO/TC 60/SC 1
Gear hobs — Accuracy requirements
Secretariat: BSI
Voting begins on: Fraises-mères — Exigences d'exactitude
20200430
Voting terminates on:
20200625
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 SUPPOR TING
DOCUMENTATION.
IN ADDITION TO THEIR EVALUATION AS
Reference number
BEING ACCEPTABLE FOR INDUSTRIAL, TECHNO
ISO/FDIS 4468:2020(E)
LOGICAL, COMMERCIAL AND USER PURPOSES,
DRAFT INTERNATIONAL STANDARDS MAY ON
OCCASION HAVE TO BE CONSIDERED IN THE
LIGHT OF THEIR POTENTIAL TO BECOME STAN
DARDS TO WHICH REFERENCE MAY BE MADE IN
©
NATIONAL REGULATIONS. ISO 2020
---------------------- Page: 1 ----------------------
ISO/FDIS 4468:2020(E)
COPYRIGHT PROTECTED DOCUMENT
© ISO 2020
All rights reserved. Unless otherwise specified, or required in the context of its implementation, no part of this publication may
be reproduced or utilized otherwise in any form or by any means, electronic or mechanical, including photocopying, or posting
on the internet or an intranet, without prior written permission. Permission can be requested from either ISO at the address
below or ISO’s member body in the country of the requester.
ISO copyright office
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Phone: +41 22 749 01 11
Fax: +41 22 749 09 47
Email: copyright@iso.org
Website: www.iso.org
Published in Switzerland
ii © ISO 2020 – All rights reserved
---------------------- Page: 2 ----------------------
ISO/FDIS 4468:2020(E)
Contents Page
Foreword .iv
1 Scope . 1
2 Normative references . 1
3 Terms, definitions and symbols . 2
3.1 Terms and definitions . 2
3.2 Symbols . 4
4 Allowable deviations . 4
5 Derivation of allowable values . 5
5.1 General . 5
5.2 Tests 16, 9, 12, 13 and 14 . 6
5.3 Test 7. 6
5.4 Test 9A . 6
5.5 Tests 10 . 6
5.6 Tests 8, 8A, 9B, 11, 11A, 12, 15 and 16 . 6
5.7 Oversize tolerances . 6
5.8 All tests . 7
Annex A (normative) Nominal dimensions of general-purpose single-start solid
(monobloc) gear hobs with axial keyway or tenon drive of 0,5 to 40 module .30
Bibliography .39
© ISO 2020 – All rights reserved iii
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ISO/FDIS 4468:2020(E)
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 nongovernmental, 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.
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
different types of ISO documents should be noted. This document was drafted 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 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. Details of
any patent rights identified during the development of 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 information given for the convenience of users and does not
constitute an endorsement.
For an explanation of the voluntary nature of standards, the meaning of ISO specific terms and
expressions related to conformity assessment, as well as information about ISO's adherence to the
World Trade Organization (WTO) principles in the Technical Barriers to Trade (TBT), see www .iso .org/
iso/ foreword .html.
This document was prepared by Technical Committee ISO/TC 60, Gears, Subcommittee SC 1,
Nomenclature and wormgearing.
This third edition cancels and replaces the second edition (ISO 4468:2009), which has been technically
revised. It also incorporates the Technical Corrigendum ISO 4468:2009/Cor 1:2009.
The main changes compared to the previous edition are as follows:
— oversize tolerances: when the hob outside diameter exceeds the recommended size given in
ISO 2490, the standard tolerances shall be increased by a factor of one-half of the percent oversize;
— hob sizes: the standard hob sizes from ISO 2490 were added as Annex A.
Any feedback or questions on this document should be directed to the user’s national standards body. A
complete listing of these bodies can be found at www .iso .org/ members .html.
iv © ISO 2020 – All rights reserved
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FINAL DRAFT INTERNATIONAL STANDARD ISO/FDIS 4468:2020(E)
Gear hobs — Accuracy requirements
1 Scope
This document specifies requirements for the accuracy of general-purpose hobs of 0,5 module to 40
module.
These hobs are intended for producing gears which conform to ISO 53 and ISO 54.
This document applies to hobs for spur and helical gears. It applies to solid (monobloc) and inserted
blade hobs.
The elemental features of hobs are graded according to accuracy, as follows:
— Grade 4A;
— Grade 3A;
— Grade 2A;
— Grade A;
— Grade B;
— Grade C;
— Grade D.
Grade 4A is the highest order of precision.
In addition to the elemental tests for hobs, this document gives permitted tolerances for composite
tests that are taken along the cutting edges on the line of action. The two groups of tests are not
equivalent and one can choose between one or the other. If there was no previous agreement, the hob is
regarded as belonging to the precision class specified if it satisfies one or the other of the two methods
of inspection.
NOTE The tolerances in this document were determined for gear hobs whose dimensions conform to
ISO 2490, but with certain precautions they can be applied to hobs not specified in this document.
2 Normative references
The following documents are referred to in the text in such a way that some or all of their content
constitutes requirements of this document. For dated references, only the edition cited applies. For
undated references, the latest edition of the referenced document (including any amendments) applies.
ISO 2862, Geometrical product specifications (GPS) — ISO code system for tolerances on linear sizes —
Part 2: Tables of standard tolerance classes and limit deviations for holes and shafts
ISO 11221, Vocabulary of gear terms — Part 1: Definitions related to geometry
ISO 27681, General tolerances — Part 1: Tolerances for linear and angular dimensions without individual
tolerance indications
© ISO 2020 – All rights reserved 1
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ISO/FDIS 4468:2020(E)
3 Terms, definitions and symbols
3.1 Terms and definitions
For the purposes of this document, the terms and definitions given in ISO 1122-1 apply.
ISO and IEC maintain terminological databases for use in standardization at the following addresses:
— ISO Online browsing platform: available at https:// www .iso .org/ obp
— IEC Electropedia: available at http:// www .electropedia .org/
3.1.1
radial runout of hub diameter
total deviation in radial distance of the hub periphery from the axis
3.1.2
axial runout of hub face
total axial deviation of the hub face from a true plane of rotation
3.1.3
radial runout of tips of teeth
total deviation in the radial distance from the axis to the tips of the hob teeth
3.1.4
straightness and radial alignment over cutting depth
angular relationship between the tooth face and a radial line intersecting the tooth face at the hob
outside diameter, measured in a plane perpendicular to the axis
3.1.5
adjacent spacing of cutting face of gashes
maximum deviation between any two consecutive cutting face measurements
3.1.6
total spacing of cutting face of gashes
maximum deviation between any two cutting face measurements
3.1.7
gash lead deviation per 100 mm
maximum deviation as the probe contacts the tooth faces within the axial region of the gash
Note 1 to entry: Allowable values for deviations are given per 100 mm of cutting face width.
3.1.8
tooth profile deviation
maximum deviation of the portion of the hob tooth that generates an unmodified involute profile
3.1.9
tooth thickness
normal tooth thickness difference of the actual and reference datum at the reference cylinder
Note 1 to entry: Tooth thickness is negative only.
3.1.9.1
addendum
radial distance between the top of the hob tooth and the reference cylinder.
2 © ISO 2020 – All rights reserved
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ISO/FDIS 4468:2020(E)
3.1.9.2
tooth thickness difference along one gash
difference between the maximum and minimum nominal tooth thickness (3.1.9) along one gash at the
reference cylinder
Note 1 to entry: Test 9B is used for tooth thickness difference along one gash. This test is only valid for quality
Grades 4A, 3A and 2A (see Table 6).
3.1.10
lead deviation on adjacent teeth
maximum lead deviation between any two consecutive teeth
3.1.11
lead deviation in one axial pitch
maximum deviation between any two teeth within any group of consecutive teeth contained in one
axial pitch
Note 1 to entry: The number of teeth in one axial pitch is the number of teeth encountered by the measurement
probe as it moves parallel to the reference axis during lead testing for a distance of one axial pitch of the hob.
Note 2 to entry: Hobs having one thread:
Measuring distance = one axial pitch = one revolution
Hobs having two threads:
Measuring distance = one axial pitch = 1/2 revolution
Hobs having three threads:
Measuring distance = one axial pitch = 1/3 revolution, etc.
Note 3 to entry: The number of teeth is determined by the number of gashes, the number of threads and, in the
case of helical gash hobs, the gash lead.
Note 4 to entry: Test 11A is used for lead deviation in one axial pitch when the line of action test is used.
3.1.12
lead deviation in three axial pitches
maximum lead deviation between any two teeth contained in three axial pitches
Note 1 to entry: The number of teeth in three distance of three axial pitches of the hob axial pitches is that number
of teeth encountered by the measurement probe as it moves parallel to the reference axis during lead testing for
a distance of three axial pitches of the hob.
Note 2 to entry: The number of teeth is determined by the number of gashes, the number of threads and, in the
case of helical gash hobs, the gash lead.
3.1.13
adjacent deviation along line of action
maximum deviation between any two consecutive teeth of a given line of action test
Note 1 to entry: Adjacent hob line of action allowable deviation can be applied to adjacent line of action test
results in those cases where the hob has been specified to be manufactured with involute helicoid geometry.
3.1.14
total deviation along line of action
total maximum deviation between any two teeth of a given line of action test
© ISO 2020 – All rights reserved 3
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ISO/FDIS 4468:2020(E)
3.1.15
axial pitch deviation from thread to thread
maximum axial pitch deviation between any two consecutive teeth contained within two gashes
Note 1 to entry: For an odd number of threads, the angle between the gashes is approximately 90°. For an even
number of threads, it is approximately 120°.
3.1.16
axial pitch deviation in any three axial pitches over all threads
maximum axial pitch deviation over any three adjacent teeth contained within two gashes
Note 1 to entry: For an odd number of threads, the angle between the gashes is approximately 90°. For an even
number of threads, it is approximately 120°.
3.2 Symbols
D hob outside diameter given by Annex A for the given module
D hob oversize outside diameter
o
K ratio for test element (see Table 3)
e
K ratio for division of module (see Table 4)
m
K ratio for grade (see Table 3)
g
K ratio for number of threads (see Table 5)
t
K standard tolerance for the test
tol
K calculated value for test i
i
K deviation test 9
9d
α hob normal pressure angle
h
4 Allowable deviations
Hobs shall conform to the requirements of Tables 2 and 4, as appropriate. The hob sizes shall be in
accordance with Annex A.
When prior agreement between the hob manufacturer and purchaser specifies measurement of hobs,
the manufacturer should select:
— the measurement method to be used from among the applicable methods described in this document
and summarized in Table 1;
— the piece of measurement equipment to be used by the selected measurement method, provided it
is in proper calibration;
— the individual teeth to be measured, as long as they are approximately equally spaced.
No particular method of measurement or documentation is considered mandatory. When applications
require measurements beyond those recommended in this document, it is recommended to negotiate
special measurement methods prior to manufacturing the hob.
4 © ISO 2020 – All rights reserved
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ISO/FDIS 4468:2020(E)
Table 1 — Reference for measurement methods
a
Test number
Test method
Test description
definition b
Elemental test Composite test
Radial runout of hub
3.1.1 1 1
diameter
3.1.2 Axial runout of hub face 2 2
Radial runout of tips of
3.1.3 3 3
teeth
Straightness and radial
3.1.4 alignment over cutting 4 4
depth
Adjacent spacing of cutting
3.1.5 5 5
face of gashes
Total spacing of cutting
3.1.6 6 6
face of gashes
Gash lead deviation per
3.1.7 7 7
100 mm
3.1.8 Tooth profile deviation 8 8A
3.1.9 Tooth thickness 9 9
Addendum difference
of values related to the
3.1.9.1 9A 9A
designed normal tooth
thickness
Tooth thickness difference
3.1.9.2 9B 9B
along one gash
Lead deviation on adja
3.1.10 10 10
cent teeth
Lead deviation in one
3.1.11 11 11A
axial pitch
Lead deviation in three
3.1.12 12 —
axial pitches
Adjacent deviation along
3.1.13 line of action (measured at Not applicable 13
the cutting edge)
Total deviation along line
3.1.14 of action (measured at the Not applicable 14
cutting edge)
Axial pitch deviation from
3.1.15 15 15
thread to thread
Axial pitch deviation in
3.1.16 any three axial pitches 16 16
over all threads
a
See Clause 5.
b
Select the composite test when the line of action test is used
5 Derivation of allowable values
5.1 General
Test 7 does not conform to a datum value and is not among the statements in Clause 5 concerning grade
relationships.
© ISO 2020 – All rights reserved 5
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ISO/FDIS 4468:2020(E)
With the exception of Test 7, the datum from which all the values in Table 6 are derived is the value of
45 µm Test 14 Grade A modules 16 to 25. See 3.2 for the explanations of symbols used.
5.2 Tests 1-6, 9, 12, 13 and 14
For tests 1 to 6, 9, 12, 13 and 14, use Formula (1):
K = 45 K K K (1)
1 to 6, 9, 12, 13, 14 e m g
5.3 Test 7
For test 7, use Formula (2):
K = 80 K (2)
7 g
5.4 Test 9A
For test 9A, use Formula (3):
K = K / [2 × tan α] (3)
9A 9d h
5.5 Tests 10
For test 10, use Formula (4):
K = 45 K K K √K (4)
10 e m g t
5.6 Tests 8, 8A, 9B, 11, 11A, 12, 15 and 16
For tests 8, 8A, 9B, 11, 11A, 12, 15 and 16, use Formula (5):
K = 45 K K K K (5)
8, 8A, 9B, 11, 11A, 12, 15, 16 e m g t
Test 9B is only valid for quality Grades 4A, 3A and 2A.
Tests 8, 8A, 9B, 10, 11, 11A, 15 and 16 are only valid for the following:
a) 1-thread, all module ranges;
b) 2-threads, module range 0,5 < m < 16;
c) 3- and 4-threads, module range 0,5 < m < 6;
d) 5, 6 and 7threads, module range 0,5 < m < 3,5.
5.7 Oversize tolerances
When the hob outside diameter exceeds the size given in Annex A, the following will apply. The standard
tolerances shall be increased by a factor of one-half of the percent oversize.
For tests 4, 5, 6, 10, 11, 11A, 12, 13, 14, 15 and 16, use Formula (6):
K = K [(D D)/D/2] + K (6)
4, 5, 6, 10, 11, 11A, 12, 13, 14, 15, 16 tol o tol
6 © ISO 2020 – All rights reserved
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ISO/FDIS 4468:2020(E)
5.8 All tests
The value of the allowable deviations has been rounded to the nearest whole value after calculation.
The minimum value of allowable deviations is 2 < m.
Standard bores shall be finished straight and parallel within the tolerances given in Table 2 for 75 % of
each bearing length for Grades 4A, 3A, 2A, A and B hobs and 50 % for Grades C and D hobs.
A reference mandrel of nominal bore diameter shall pass through the bore as a check of alignment.
The tolerances on bore diameter are specified in Table 2.
Table 2 — Tolerance on bores
a
Tolerance
Grade Datum diameter
of hob mm
8 10 13 16 22 27 32 40 50 60 80
4A H3
3A H4
H3
2A
A H4 H5
B H5
C
H6
D
a
The tolerance shall be in accordance with ISO 2862.
Table 3 — Ratio for test element and grade
Test Ratio of test element Ratio of grade
number
K
K
e g
4A 3A 2A A B C D
1 0,3
1,6 1,6 2,11
2 0,25
3 1,6 3,6 4,75
4 1,25
1,8
5 1,4 0,35 0,5 0,71 2,38
1,8
6 2,6 1
7 No relationship to test 14 1,25 2,31
8 0,5
4 5,28
8A 0,85
2
9 1,5
0,71 0,71 1 2 2,54
9A As by Table 4
a
The tolerance shall be in accordance with ISO 2862.
© ISO 2020 – All rights reserved 7
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ISO/FDIS 4468:2020(E)
Table 3 (continued)
Test Ratio of test element Ratio of grade
number
K
K
e g
4A 3A 2A A B C D
9B 0,8 — — — —
10 0,4
11 0,7
11A 0,8
12 1,3 0,35 0,5 0,71
1 2 4 5,28
13 0,4
14 1
15 0,45
16 0,8
a
The tolerance shall be in accordance with ISO 2862.
The ratio for division of module s are defined in Table 4.
Table 4 — Ratio for division of module
Module range Ratio for module range Multiplication
m K factor
m
0,5 < m < 1 0,33
1,12
1 < m < 2 0,37
1,12
2 < m < 3,5 0,41
1,25
3,5 < m < 6,0 0,51
1,25
6,0 < m < 10 0,64
1,25
10 < m < 16 0,8
1,25
16 < m < 25 1
1,32
25 < m < 40 1,32
The ratio for number of threads are defined in Table 5.
8 © ISO 2020 – All rights reserved
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ISO/FDIS 4468:2020(E)
Table 5 — Ratio for number of threads
Number Ratio for number Multiplication
of threads of threads factor
K
t
1 1 1,25
2 1,25
1,25
3,4 1,56
1,25
5,6,7 1,95
The accuracy requirements are defined in Table 6.
© ISO 2020 – All rights reserved 9
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ISO/FDIS 4468:2020(E)
10 © ISO 2020 – All rights reserved
Table 6 — Accuracy requirements
Allowable deviation
Test Pitch range
µm
Element Drawing Object of test
No module, m
Grade
(See the end of this table for the key to the drawings.) mm 4A 3A 2A A B C D
0,5 < m < 1 2 2 3 4 7 7 9
1 < m < 2 2 2 4 5 8 8 11
2 < m < 3,5 2 3 4 6 9 9 12
3,5 < m < 6,0 2 3 5 7 11 11 15
1 Hub diameter Radial runout
6,0 < m < 10 3 4 6 9 14 14 18
10 < m < 16 4 5 8 11 17 17 23
16 < m < 25 5 7 10 14 22 22 28
25 < m < 40 6 9 13 18 29 29 38
0,5 < m < 1 2 2 3 4 6 6 8
1 < m < 2 2 2 3 4 7 7 9
2 < m < 3,5 2 2 3 5 7 7 10
3,5 < m < 6,0 2 3 4 6 9 9 12
2 Hub face Axial runout
6,0 < m < 10 3 4 5 7 12 12 15
10 < m < 16 3 5 6 9 14 14 19
16 < m < 25 4 6 8 11 18 18 24
25 < m < 40 5 7 11 15 24 24 31
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ISO/FDIS 4468:2020(E)
© ISO 2020 – All rights reserved 11
Table 6 (continued)
Allowable deviation
Test Pitch range
µm
Element Drawing Object of test
No module, m
Grade
(See the end of this table for the key to the drawings.) mm 4A 3A 2A A B C D
0,5 < m < 1 8 12 17 24 43 86 113
1 < m < 2 9 13 19 27 48 96 127
2 < m < 3,5 10 15 21 30 53 106 140
3,5 < m < 6,0 13 18 26 37 66 132 174
Outside Radial runout of
3
diameter tips of teeth
6,0 < m < 10 16 23 33 46 83 166 219
10 < m < 16 20 29 41 58 104 207 274
16 < m < 25 25 36 51 72 130 259 342
25 < m < 40 33 48 67 95 171 342 451
0,5 < m < 1 6 9 13 19 33 33 44
1 < m < 2 7 10 15 21 37 37 50
2 < m < 3,5 8 12 16 23 42 42 55
Straightness and
3,5 < m < 6,0 10 14 20 29 52 52 68
Cutting face of
4 radial alignment
gashes
6,0 < m < 10 13 18 26 36 65 65 86
over cutting depth
10 < m < 16 16 23 32 45 81 81 107
16 < m < 25 20 28 40 56 101 101 134
25 < m < 40 26 37 53 74 134 134 177
0,5 < m < 1 7 10 15 21 37 37 49
1 < m < 2 8 12 17 23 42 42 55
2 < m < 3,5 9 13 18 26 46 46 61
3,5 < m < 6,0 11 16 23 32 58 58 76
Cutting face of
5 Adjacent spacing
gashes
6,0 < m < 10 14 20 29 40 73 73 96
10 < m < 16 18 25 36 50 91 91 120
16 < m < 25 22 32 45 63 113 113 150
NOTE The numbers 1, 2, 3, etc. refer to the cutting teeth on the hob.
25 < m < 40 29 42 59 83 150 150 198
---------------------- Page: 15 ----------------------
ISO/FDIS 4468:2020(E)
12 © ISO 2020 – All rights reserved
Table 6 (continued)
Allowable deviation
Test Pitch range
µm
Element Drawing Object of test
No module, m
Grade
(See the end of this table for the key to the drawings.) mm 4A 3A 2A A B C D
0,5 < m < 1 14 19 27 39 69 69 92
1 < m < 2 15 22 31 43 78 78 103
2 < m < 3,5 17 24 34 48 86 86 114
3,5 < m < 6,0 21 30 42 60 107 107 142
Cutting face of
6 Total spacing
gashes
6,0 < m < 10 26 37 53 75 135 135 178
10 < m < 16 33 47 66 94 168 168 223
16 < m < 25 41 59 83 117 211 211 278
NOTE The numbers 1, 2, 3, etc. refer to the cutting teeth on the hob.
25 < m < 40 54 77 110 154 278 278 368
Cutting face of Gash lead devia
7 0,5 < m < 40 28 40 57 80 100 144 185
gashes tion per 100 mm
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ISO/FDIS 4468:2020(E)
© ISO 2020 – All rights reserved 13
Table 6 (continued)
Allowable deviation
Test Pitch range
µm
Element Drawing Object of test
No module, m
Grade
(See the end of this table for the key to the drawings.) mm 4A 3A 2A A B C D
0,5 < m < 1 3 4 5 7 15 30 39
1 < m < 2 3 4 6 8 17 33 44
2 < m < 3,5 3 5 7 9 18 37 49
Tooth profile
3,5 < m < 6,0 4 6 8 11 23 46 61
6,0 < m < 10 5 7 10 14 29 58 76
1thread
10 < m < 16 6 9 13 18 36 72 95
16 < m < 25 8 11 16 23 45 90 119
25 < m < 40 10 15 21 30 59 119 157
0,5 < m < 1 3 5 7 9 19 37 49
1 < m < 2 4 5 7 10 21 42 55
2 < m < 3,5 4 6 8 12 23 46 61
3,5 < m < 6,0 5 7 10 14 29 57 76
8 Tooth 2threads
6,0 < m < 10 6 9 13 18 36 72 95
10 < m < 16 8 11 16 23 45 90 119
16 < m < 25 — — — — — — —
25 < m < 40 — — — — — — —
0,5 < m < 1 4 6 8 12 23 46 61
1 < m < 2 5 6 9 13 26 52 69
2 < m < 3,5 5 7 10 14 29 58 76
3,5 < m < 6,0 6 9 13 18 36 72 95
3, 4threads
6,0 < m < 10 — — — — — — —
10 < m < 16 — — — — — — —
16 < m < 25 — — — — — — —
25 < m < 40 — — — — — — —
---------------------- Page: 17 ----------------------
ISO/FDIS 4468:2020(E)
14 © ISO 2020 – All rights reserved
Table 6 (continued)
Allowable deviation
Test Pitch range
µm
Element Drawing Object of test
No module, m
Grade
(See the end of this table for the key to the drawings.) mm 4A 3A 2A A B C D
0,5 < m < 1 5 7 10 14 29 58 76
1 < m < 2 6 8 12 16 32 65 86
2 < m < 3,5 6 9 13 18 36 72 95
3,5 < m < 6,0 — — — — — — —
8 5, 6, 7threads
6,0 < m < 10 — — — — — — —
10 < m < 16 — — — — — — —
16 < m < 25 — — — — — — —
25 < m < 40 — — — — — — —
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ISO/FDIS 4468:2020(E)
© ISO 2020 – All rights reserved 15
Table 6 (continued)
Allowable deviation
Test Pitch range
µm
Element Drawing Object of test
No module, m
Grade
(See the end of this table for the key to the drawings.) mm 4A 3A 2A A B C D
0,5 < m < 1 4 6 9 13 25 50 67
1 < m < 2 5 7 10 14 28 57 75
2 < m < 3,5 5 8 11 16 31 63 83
Tooth profile
(when line of ac
3,5 < m < 6,0 7 10 14 20 39 78 103
tion test is used)
6,0 < m < 10 9 12 17 24 49 98 129
1thread
10 < m < 16 11 15 22 31 61 112 162
16 < m < 25 13 19 27 38 77 153 202
25 < m < 40 18 25 36 50 101 202 267
0,5 < m < 1 6 8 11 16 32 63 83
1 < m < 2 6 9 13 18 35 71 93
2 < m < 3,5 7 10 14 20 39 78 104
3,5 < m < 6,0 9 12 17 24 49 98 129
8A Tooth 2threads
6,0 < m < 10 11 15 22 31 61 122 162
10 < m < 16 13 19 27 38 77 153 202
16 < m < 25 — — — — — — —
25 < m < 40 — — — — — — —
0,5 < m < 1 7 10 14 20 39 79 104
1 < m < 2 8 11 16 22 44 88 117
2 < m < 3,5 9 12 17 24 49 98 129
3,5 < m < 6,0 11 15 22 30 61 122 161
3, 4threads
6,0 < m < 10 — — — — — — —
10 < m < 16 — — — — — — —
16 < m < 25 — — — — — — —
25 < m < 40 — — — — — — —
---------------------- Page: 19 ----------------------
ISO/FDIS 4468:2020(E)
16 © ISO 2020 – All rights reserved
Table 6 (continued)
Allowable deviation
Test Pitch range
µm
Element Drawing Object of test
No module, m
Grade
(See the end of this table for the key to the drawings.) mm 4A 3A 2A A B C D
0,5 < m < 1 9 12 17 25 49 98 130
1 < m < 2 10 14 20 28 55 110 146
2 < m < 3,5 11 15 22 31 61 122 161
3,5 < m < 6,0 — — — — — — —
8A 5, 6, 7threads
6,0 < m < 10 — — — — — — —
10 < m < 16 — — — — — — —
16 < m < 25 — — — — — — —
25 < m < 40 — — — — — — —
0,5 < m < 1 16 16 22 22 45 45 57
1 < m < 2 18 18 25 25 50 50 63
2 < m < 3,5 20 20 28 28 55 55 70
Normal tooth
3,5 < m < 6,0 24 24 34 34 69 69 87
9 Tooth thickness
6,0 < m < 10 31 31 43 43 86 86 110
(negative only)
10 < m < 16 38 38 54 54 108 108 137
16 < m < 25 48 48 68 68 135 135 171
25 < m < 40 63 63 89 89 178 178 226
0,5 < m < 1
1 < m < 2
2 < m < 3,5
3,5 < m < 6,0
Addendum Deviations from test 9 divided by
9A Tooth
(positive only) 2*tan (pressure angle)
6,0 < m < 10
10 < m < 16
16 < m < 25
25 < m < 40
---------------------- Page: 20 ----------------------
ISO/FDIS 4468:2020(E)
© ISO 2020 – All rights reserved 17
Table 6 (continued)
Allowable deviation
Test Pitch range
µm
Element Drawing Object of test
No module, m
Grade
(See the end of this table for the key to the drawings.) mm 4A 3A 2A A B C D
0,5 < m < 1 4 6 8
1 < m < 2 5 7 9
Difference be
tween maximum 2 < m < 3,5 5 7 10
and minimum
3,5 < m < 6,0 6 9 13
normal tooth
thickness along 6,0 < m < 10 8 12 16
one gash
10 < m < 16 10 14 20
1thread
16 < m < 25 13 18 26
25 < m < 40 17 24 34
0,5 < m < 1 5 7 11
1 < m < 2 6 8 12
2 < m < 3,5 6 9 13
3,5 < m < 6,0 8 11 16
Test 9B is only valid for
9B Tooth 2threads
quality grade 4A, 3A and 2A.
6,0 < m < 10 10 14 20
10 < m < 16 13 18 26
16 < m < 25 — — —
25 < m < 40 — — —
0,5 < m < 1 6 9 13
1 < m < 2 7 10 15
2 < m < 3,5 8 12 16
3,5 < m < 6,0 10 14 20
3, 4threads
6,0 < m < 10 — — —
10 < m < 16 — — —
16 < m < 25 — — —
25 < m < 40 — — —
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ISO/FDIS 4468:2020(E)
18 © ISO 2020 – All rights reserved
Table 6 (continued)
Allowable deviat
...
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