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Disclosure to Promote the Right To Information
Whereas the Parliament of India has set out to provide a practical regime of right to information for citizens to secure access to information under the control of public authorities, in order to promote transparency and accountability in the working of every public authority, and whereas the attached publication of the Bureau of Indian Standards is of particular interest to the public, particularly disadvantaged communities and those engaged in the pursuit of education and knowledge, the attached public safety standard is made available to promote the timely dissemination of this information in an accurate manner to the public.
इंटरनेट मानक
“!ान $ एक न' भारत का +नम-ण”Satyanarayan Gangaram Pitroda
“Invent a New India Using Knowledge”
“प0रा1 को छोड न' 5 तरफ”Jawaharlal Nehru
“Step Out From the Old to the New”
“जान1 का अ+धकार, जी1 का अ+धकार”Mazdoor Kisan Shakti Sangathan
“The Right to Information, The Right to Live”
“!ान एक ऐसा खजाना > जो कभी च0राया नहB जा सकता है”Bhartṛhari—Nītiśatakam
“Knowledge is such a treasure which cannot be stolen”
“Invent a New India Using Knowledge”
है”ह”ह
IS 8733 (1978): Tolerances for single start gear hobs [PGD32: Cutting tools]
UDC 821’914’8 : 621’833: 621’753’1 IS : 9733 - 1978
[s1
Indian Standard
1 I TOLERANCES FOR
SINGLE START GEAR HOBS
I. Scope - Covers the tolerances for single start gear hobs, suitable for modules 1 to 20, conform- ng to IS : 2535-1978 ‘ Basic rack and modules of cylindrical gears for general engineering and heavy 3ngineering ( second revision) ‘. The tolerances specified in the standard apply to all pressure angles.
2. Grades
!.l Gear hobs shall be classified into the following grades of accuracy:
Grade AA High precision ground hobs
Grade A Precision aground hobs
Grade B Commercial ground hobs
Grade C Precision ungiound hobs
Grade D Commercial unground hobs
2.2 Bearing surface length of bore for all grades shall be 66 percent except for Grade AA.
EXPLANATORY NOTE
In the preparation of this standard considerable assistance has been derived from DIN 3968- 1960 ‘ Toleranzen eingangiger Walzfraser fur Stirnrader mit Evolventenverzahnung (Tolerances for single-start hobs for involute spur gears ) ’ issued by Deutsches lnstitut fiir Normung.
Adopted 23 February 1978 Q August 1978, ISI I
~~~~~ ,id
INDIAN STANDARDS INSTITUTION MANAK BHAVAN, 2 BAHADUR SHAH ZAFAR MARG
NEW DELHI llOW2
3. Tolerances All tolerances in miciometres I 1 miciometre = 0’001 mm 1.
SI No.
Element to be
Checked
Illustration Symbol for
Tolerance
Grade Module
For Over Over Over Over Over Over Over 1 1 .
up to “;Yo ,;:o “ito “i3to u;to “lpGt0 1’6 2’5 4 6’3 10 16 20
AA H5t
A R5t Tolerance on
1 bore diameter * - B (d)*
H6t
C R6t
D l-W
2 Form tolerance of bore*
- All grades
One half the bore tolerance
Inteichange- All grades
According to IS : 6285-1971 ‘ Dimensions for interchangeability of milling cutters
3 able tole- and milling arbors with key drive ’ - - rance for keyway
AA 5 5 5 5 5 5 I 6 I 6
A 5 5 5 6 8 10 12 16 Radial 1
I
___ 1 ____ runout of hub
4 diameter with frP B 6 6 6 8 1 IO 12 16 20 respect to
-I..
_~_~~~ _ bore axis
C 10 IO 10 12 1 16 20 25 32
D Not defined
‘Bores with recess are to be treated as a single-diameter tnrough bore with regard to diameter and torm tolerances. For hobs of Grade AA, it is desirable that the bore should not be made with a recess.
TAccording to IS : 919-1963 ‘ Recommendations for limits and fits for engineering (revised) ‘.
( Continued )
All tolerances in miciometres ( 1 micrometie = 0’001 mm ).
-
?
--
_
_
-
-
-
-
-
-
Iti,
-
5
E:sombeen* Checked
Illustration Sw&bol
roleranct
fR8
Grade’
AA
Module
I -
I T Over
“pit0 1’6
3
Over
“;:o 2’5
3
3
4
6
Over 2’5
up to 4
3
5
6
10
Over
U&o 6.3
3
Over 6’3
up to 10
Over
“‘POW 16
Over
“$0 20
4 5
--
-.
--
5
5 8 3 10
6 10
.-
.-
10 12
_-
10 16 16 20
16 25 25 32
For 1
3
40
63
125
250
500
A 3 3
B 4
C 6
D
AA
10
10
fifx~;40yut
both faces with respect to bore axis
IO 12 16
12 16
20 25
___~
40 50
~__
80 100
160 200
10 20
32
25 32
A
B
40 50
--
30 100
12 16
25 32
Radial runotit on tooth tips with respect to bore axis
_-
6 frk 63
~I-
50 63 125 160 200
-1
250 315 400 100 125
P
All tolerances in micidmetres ( 1 miciometie = 0’001 mm 1.
Checked
Illustration Svmbal
Form and positional tolerance of cutting faces
DISTANCE U IS TM AMOUNT
BY WHICH DESIGN LINE
is INSTANT FROM PLANE OF HOB AXIS
(ZERO WHEN RAKE ANGLE IS O”)
I-_- CUTTING oEPTH----s(
TOOTH TIP\
TEST DIAGRAM
FIN
(Continued)
All tolerances in micrometies ( 1 miciometie = 0’001 mm ).
cn
Element to be
Chcrked
Illustration GYftyI Grade Module
Tolerance Foi - Over Ovei Ovrr Over Over Over
1 U;; go . uyo 6; O;83r I U~ot~ $0 . . 16 Ui,.
AA f 10 fl0 *12 zt 16 rt20 *225 f32 f4g
A *in fl6 f20 f25 f32 &40 zt 50 f63
Tolerance on -- 8 z;itlspacing
middle of fm* B =t25 f32 fm =tr5g zt63 &80 f 100 f 125
the tooth height
C f50 f63 *&I fig0 fl25 &NO zt2ocl f250
I
123C56789lfJ1112 D f 100 f 125 fl00 f2W f250 f315 f400 f 500
TEST DIAGRAM
AA 10 10 12 16. 20 25 32 40
Maximum tooth spacing
A 12 16 20 25 32 40 50 63
9 erroi bet- ween two ZERO flat B 25 32 40 50 63 80 100 125 adjacent -- -P teeth
C 50 63 30 100 125 130 200 250
1 2 3 1 5 6 7 3 9 10 1112 D
I 100 125 130 2M) 250
I 315 400 500
VN is the difference between the actual value and designed value of the gash spacing.
tTooth spacing error fuN is the actual difference in the spacing of two adjacent gashes.
( Continued )
All tolerances In miciometres f 1 micrometre = 0’001 mm 1.
SI No.
Element to be
Checked
Maximum cumulative tooth spac- ing error measured at half tooth height
--
11
Lead orror of gash over 100 mm hob length
illustration
1 2 3 L 5 6 7 8 9 10 1112
TEST DIAGRAM
roe mmI
f HN
S~~rbol
Tolerance
--
h*
fIiN
I Grade Module
Foi * Ovei Over Ovef OY’
Over Over Over 1 d; ul,!o . 6’3 10
2’6 ui:o usp; . Ur0to Upe’” ito
AA 20 20 25 32 40 50 63 80
A 25 32 40 50 63 80 100 125
B 50 63 80 100 125 160 200 210
C 100 125 160 260 250 315 400 500
D 2w 250 315 400 500 630 800 1000
AA
A
B
C
D
I
fW
f 70
f 100
f140
fnao
*The tolerance Ft~ is referred to the total pitch eiror, that is to say that the krgest Cumulative pitch error measured on the hob tested.
( COntifWsd J
All tolerances in miciometres ( 1 micrometre = 0’001 mm 1.
Element to be
Checked
-
1 -
s,,y1
Tolerance
Module Illustration drade
T
For a Over Over 1 Oit’ Over Over Over
up to u;to $0 4 6’3 16
Over
u;to
18
32
63
125
- 50
-50
-160
- 320
-320
f12
*20
f40
f60
6 6
10 12
20 25 --
40 50
. .
_
~ _
-
__
AA _-
_-
.-
.-
A ,-
Permissible error over the straight flank from ;z;iesign
B FfS
fi
_‘_
I - C
D
AA
Not defined
-20 - 25 -32 - 40
-36 -40 - 50 - 63
- 71 -60 - 100 - 125
-146 - 160 -200 -250
- 140 - 160 - 200 - 250
f5 f6 &6 f 10
f9 *lo f12 f 16
fl6 lt2o 525 rt 32
f36 rt40 f50 . +63
- 16
-25
-56
-106
- 100
f4
f6
f12
f25
f50
- 16 - 16
-28 - 32
-56 -63
- 112 - 125
-112 - 125
f4 f4
&I7 f8
fl4 ft6
f28 f 32
556 f63
A Tolerance on tooth thick- ness on the pitch cylinder
B
C
D
=fHF
AA
A
Hob lead from cutting edge to cutt- ing edge in Lyh”,i;ction
fHF B
where HN = lead of gashes, H = hob lead ( helix), and i = number of gashes or tooth rows. The sign in the parentheses is plus ( +) if gash lead and the hob lead are in the opposite direction, and negative ( - ) If they are in the same direction
C
I -IpI I ! f)
f71 1 zt60 1 fl60 / f125 / &I60 D
( Continuea
Ipa- . .
All tolerances in micrometres ( 1. micrometre = 0’001 mm ).
IE!. Element to be
Chebked
Grade Module Symbol for
rolerance
Illustration -
For 1
Over Over
&to L&s,0 1’6 2’5
AA 6 6 6
10 11
22
12
20
40
25
45 50
D 80 90 100 112 125
AA f4 *4
.-
_ *4
-
_.
-
_ -
--
-
--
--
--
-
-
Over
U&o 6’3
Over
u6p3t 0 10
10 12
16 20
28 32 40
56 63 80
160
*5 f6
ItI9
*20
f 49
-.
_-
-_
-
zt:25 f32 f40
* 50 f 63 rt80
-
_.
-_
-
Over
u;to
Over 16
up to 20
14 18
25 32
50
190
200
-
-_
- .
__
- _
. -
-i
63
125
250
f IO f12
3116 f20
__
Over
“;5to 4
8
14
f9
518
f 36
n.HN.H
ilHN=H) =FHF
t-l
Hob lead in ;yhf;rtion
between any two cutting edges on the same thread
15 FHP where
HN = Lead of gashes,
H = hob lead ( helix ), i = number of gashes or tooth rows, and n = number of cutting edges on which the
measurement is made. The sign in the parentheses is plus (+ ) if gash lead and the hob lead are in the opposite direction, and negative ( - ) if they are in the same direction
rt6 &7 f8
fl2 f 14 f ‘6
f25 f 28 d.132
A
B Individual base pitch error
16 fe
C where
te = base pitch, ahd
i = number of gashes
D Not defined
( Continued)
All toleiances in micrometres ( 1 micromktre = 0’001 mm ).
Element to be
Checked
Illustration Grade Module SytT,bol
Tolerance
For 1
Over 1
up to 1’6
Over
“iat 2’5
Over .
u’,:o 4
Over
u;io
Over
“ito
Over
u;io
Over
uyo
16
Cumulative base pitch error within the contact region
AA 8 8 8 10 12 25
14 16 25 32 40
80
160
18
36 17
TEST DIAGRAM -
18
Diametei tolerance over hob length
-
28 32 63
125
25
50 56 63 II 80 100
D Not defined
--
20
-
_-
.-
.-
-
25 32 AA 8 8
___~
i0 12
20 25
40 50
12
20
40
80
Not defined
10
16
32
63
16
25
50
100
A 50
100
32
63
40
80
C 125
---
160 200
D