Limits Fits
-
Upload
ezhil-arasan -
Category
Documents
-
view
165 -
download
16
description
Transcript of Limits Fits
-
Fundamentals of LIMITS, FITS and TOLERANCES
-
Tolerance: Tolerance is the total permissible variation from the specified basic size of the part. It is defined as the magnitude of permissible variation of a dimension or measured control criterion from specified value.Basic size: The basic size is the size on which variation permitted.
Actual size: The size of a feature obtained by measurement
-
TOL not specifiedFollow general engineering toleranceIS 2102 fine, medium, course & very courseUnless otherwise specified, it is medium.Or else it can be IT 14 VALUE, bilateralAll drawings need contain conditions on general tolerance.
-
1. Open tolerances or General Engineering tolerancesStandards used are IS 2102 ( Part 1) 1993 / ISO 2768 - 1 : 1989General TolerancesPart 1: Tolerances for Linear and Angular dimensions without individual tolerance indicationsPart 2: Geometrical Tolerances for features without individual tolerance indicationsEx: 20.0, 20-f, 20-f H
-
Table 1 Permissible deviations for linear dimensions except for broken edges(external radii and chamfer heights, see table 2)Values in millimeters
Tolerance ClassPermissible deviations for basic size rangeDesignationDescription0.5up to3Over3up to6Over6up to30Over30up to120Over120up to120Over400up to400Over1000up to2000Over2000up to4000ffine 0,05 0,05 0,1 0,15 0,2 0,3 0,5-mmedium 0,1 0,1 0,2 0,3 0,5 0,8 1,2 2ccoarse 0,2 0,3 0,5 0,8 1,2 2 3 4vvery coarse- 0,5 1 1,5 2,5 4 6 81) For nominal sizes below 0,5 mm, the deviations shall be indicated adjacent to the relevant nominal size (s).
-
Table 2 Permissible deviations for broken edges ( external radii and chamfer heights) Values in millimeters
Tolerance ClassPermissible deviations for basic size rangeDesignationDescription0.5 up to 3Over 3 up to6over 6ffine 0,2 0,5 1mmediumccoarse 0,4 0,1 2vvery coarse1) For nominal sizes below 0.5 mm, the deviations shall be indicated adjacent to the relevant nominal size(s).
-
Table 3 Permissible deviations of angular dimensions
Tolerance ClassPermissible deviations for ranges of lengths, in millimeters,of the shorter side of the angle concernedDesignationDescriptionup to 10over 10 up to 50over 50 up to 120over 120 up to 400over 400Ffine 10 00 30 00 20 00 10 00 5mmediumccoarse 10 30 10 00 30 00 15 00 10vvery coarse 30 20 10 00 30 00 20
-
Table 1 General tolerances on straightness and flatness Values in millimeters
-
Table-2 General tolerances on perpendicularityValues in millimeters
-
Table-3 General tolerances on symmetry Values in millimeters
-
Table 4 General tolerances on circular run-outValues in mm
-
IS 2102 PART 2VALUES FOR Straightness / perpendicularity / symmetry / Run out specifiedCircularity - limited to diameter tolerance or run out valueCylindricity Limited to combined effect of CIRCULARITY& PARALLELISM.Parallelism Limited to Dimensional Tolerance & flatness tolerance.Coaxiality - Limited to run out tolerance.
-
ISO 2768 - mGeneral Engg. Tole Tolerance class medium
IS 2102 fGeneral Engg. Tole class fine
-
ISO 2768 mK
General Engg. Tole for dimensions - Tolerance class. mGeneral Engg. Tole for form / position tolerance class. K
-
ISO 2768 - KGeneral tol. as dim not considered. Form/position as per tol. Class K.
-
SPECIFIED TOLERANCEVALUE GIVENVALUE AND POSISTIONAL STATUS GIVENSTD.SYMBOLS USED.
-
2. Specificied tolerancesStandards usedIS 919 (Part 1) 1993 / ISO 286 1 : 1988ISO System of Limits and Fits
Part 1: Bases of tolerances, Deviations and FitsPart 2:Tables of standard tolerance Grades and limit Deviations for Holes and shaft.
Example : 20H7, 20g6, 30 + 0.02
Specific tolerance should be less than open tolerance
-
STANDARD SPECIFICATION Need contain
HOW MUCH IS THE VALUE OF TOL.WHERE IT IS DISPOSED.
-
HOW MUCH IS THE VALUEIS 919 / SP46 OR STD CHARTS SPECIFY.18 GRADES ARE SPECIFIED. VALUE IS ATTACHED TO A GRADEIT=INTERNATIONALTOLERANCE GRADE.AND 18 REPRESENT THE ROUGHFEST Mfg processEVERY MANUFACTURING PROCESS IS ATTRIBUTED WITH A RANGE OF ACCURACY GRADE
-
HOW MUCH IS THE VALUE FOR EX;TURNING IT7, 8 OR 9 GRINDING IT 5, OR 7MILLING IT 6, 7, OR 8LAPPING IT 1, 2, 3, OR 4SAND CASTING IT 16, 17, 18PRESS WORKING IT 10, 11 OR 12INJ. MOULDINGIT 12. 123 OR 14
-
Grades of tolerances obtainable by various manufacturing processes
According to IS 18 grades of tolerances or accuracy grades of manufacturing IT1, IT2, IT3.IT18
IT GRADE is generally indicated by numbers from 1 to 18
-
HOW MUCH IS THE VALUE. EVERY DIM. ALONG WITH A GRADE RECEIVE A TOL. VALUE.FOR EX. DIM 40 & GRADE 8, TOL= ?STD. FORMULA APPLIES TO THIS VALUEFOR CONVENIENCE, DIMES. ARE GROUPED. 0 TO 3; 3 TO 6; 6 TO 10 etc.SAME VALUE OF TOL. VALID FOR A DIA GROUP WITH ONE GRADE.
-
Table 1 Numerical values of standard tolerance grades IT for basic sizes up to 3 150 mm
Basic size
mm
Standard tolerance grades
IT12)
IT22)
IT32)
IT42)
IT52)
IT6
IT7
IT8
IT9
IT10
IT11
IT12
IT13
IT143)
IT153)
IT163)
IT173)
IT183)
Above
Up to
and in- cluding
Tolerances
(m mm
-
33
0,8
1,2
2
3
4
6
10
14
25
40
60
0,1
0,14
0,25
0,4
0,6
1
1,4
3
6
1
1,5
2,5
4
5
8
12
18
30
48
75
0,12
0,18
0,3
0,48
0,75
1,2
1,8
6
10
1
1,5
2,5
4
6
9
15
22
36
58
90
0,15
0,22
0,36
0,58
0,9
1,5
2,2
10
18
1,2
2
3
5
8
11
18
27
43
70
110
0,18
0,27
0,43
0,7
1,1
1,8
2,7
18
30
1,5
2,5
4
6
9
13
21
33
52
84
130
0,21
0,33
0,52
0,84
1,3
2,1
3,3
30
50
1,5
2,5
4
7
11
16
25
39
62
100
160
0,25
0,39
0,62
1
1,6
2,5
3,9
50
80
2
3
5
8
13
19
30
46
74
120
190
0,3
0,46
0,74
1,2
1,9
3
4,6
80
120
2,5
4
6
10
15
22
35
54
87
140
220
0,35
0,54
0,87
1,4
2,2
3,5
5,4
120
180
3,5
5
8
12
18
25
40
63
100
160
250
0,4
0,63
1
1,6
2,5
4
6,3
180
250
4,5
7
10
14
20
29
46
72
115
185
290
0,46
0,72
1,15
1,85
2,9
4,6
7,2
250
315
6
8
12
16
23
32
52
81
130
210
320
0,52
0,81
1,3
2,1
3,2
5,2
8,1
315
400
7
9
13
18
25
36
57
89
140
230
360
0,57
0,89
1,4
2,3
3,6
5,7
8,9
400
500
8
10
15
20
27
40
63
97
155
250
400
0,63
0,97
1,55
2,5
4
6,3
9,7
500
6302
9
11
16
22
32
44
70
110
175
180
440
0,7
1,1
1,75
2,8
4,4
7
11
630
8002
10
13
18
25
36
50
80
125
200
320
500
0,8
1,25
2
3,2
5
8
12,5
800
10002
11
15
21
28
40
56
90
140
230
360
560
0,9
1,4
2,3
3,6
5,6
9
14
1000
12502
13
18
24
33
47
66
105
165
260
420
660
1,05
1,65
2,6
4,2
6,6
10,5
16,5
1250
16002
15
21
29
39
55
78
125
195
310
500
780
1,25
1,95
3,1
5
7,8
12,5
19,5
1600
20002
18
25
35
46
65
92
150
230
370
600
920
1,5
2,3
3,7
6
9,2
15
23
2000
25002
22
30
41
55
78
110
175
280
440
700
1100
1,75
2,8
4,4
7
11
17,5
28
2500
31502
26
36
50
68
96
135
210
330
540
860
1350
2,1
3,3
5,4
8,6
13,5
21
33
1) Values for standard tolerance grades IT01 and IT0 for basic sizes less than or equal to 500 mm are given in ISO 286 1, annex A, table 5.
2) Values for standard tolerance grades IT1 to IT5 (incl.) for basic sizes over 500 mm are included for experimental use.
3) Standard tolerance grades IT14 to IT18 (incl.) shall not be used for basic sizes less than or equal to 1 mm.
-
Table 1 Numerical values of standard tolerance grades IT for basic sizes up to 3 150 mm
Basic size
mm
Standard tolerance grades
IT12)
IT22)
IT32)
IT42)
IT52)
IT6
IT7
IT8
IT9
IT10
IT11
Above
Up to
and including
Tolerances
(m
-
33
0,8
1,2
2
3
4
6
10
14
25
40
60
3
6
1
1,5
2,5
4
5
8
12
18
30
48
75
6
10
1
1,5
2,5
4
6
9
15
22
36
58
90
10
18
1,2
2
3
5
8
11
18
27
43
70
110
18
30
1,5
2,5
4
6
9
13
21
33
52
84
130
30
50
1,5
2,5
4
7
11
16
25
39
62
100
160
50
80
2
3
5
8
13
19
30
46
74
120
190
80
120
2,5
4
6
10
15
22
35
54
87
140
220
120
180
3,5
5
8
12
18
25
40
63
100
160
250
180
250
4,5
7
10
14
20
29
46
72
115
185
290
250
315
6
8
12
16
23
32
52
81
130
210
320
315
400
7
9
13
18
25
36
57
89
140
230
360
400
500
8
10
15
20
27
40
63
97
155
250
400
500
6302
9
11
16
22
32
44
70
110
175
180
440
630
8002
10
13
18
25
36
50
80
125
200
320
500
800
10002
11
15
21
28
40
56
90
140
230
360
560
1000
12502
13
18
24
33
47
66
105
165
260
420
660
1250
16002
15
21
29
39
55
78
125
195
310
500
780
1600
20002
18
25
35
46
65
92
150
230
370
600
920
2000
25002
22
30
41
55
78
110
175
280
440
700
1100
2500
31502
26
36
50
68
96
135
210
330
540
860
1350
1) Values for standard tolerance grades IT01 and IT0 for basic sizes less than or equal to 500 mm are given in ISO 286 1, annex A, table 5.
2) Values for standard tolerance grades IT1 to IT5 (incl.) for basic sizes over 500 mm are included for experimental use.
3) Standard tolerance grades IT14 to IT18 (incl.) shall not be used for basic sizes less than or equal to 1 mm.
-
Table 1 Numerical values of standard tolerance grades IT for basic sizes up to 3 150 mm
Basic size
mm
Standard tolerance grades
IT12
IT13
IT143)
IT153)
IT163)
IT173)
IT183)
Above
Up to and
including
Tolerances
mm
-
33
0,1
0,14
0,25
0,4
0,6
1
1,4
3
6
0,12
0,18
0,3
0,48
0,75
1,2
1,8
6
10
0,15
0,22
0,36
0,58
0,9
1,5
2,2
10
18
0,18
0,27
0,43
0,7
1,1
1,8
2,7
18
30
0,21
0,33
0,52
0,84
1,3
2,1
3,3
30
50
0,25
0,39
0,62
1
1,6
2,5
3,9
50
80
0,3
0,46
0,74
1,2
1,9
3
4,6
80
120
0,35
0,54
0,87
1,4
2,2
3,5
5,4
120
180
0,4
0,63
1
1,6
2,5
4
6,3
180
250
0,46
0,72
1,15
1,85
2,9
4,6
7,2
250
315
0,52
0,81
1,3
2,1
3,2
5,2
8,1
315
400
0,57
0,89
1,4
2,3
3,6
5,7
8,9
400
500
0,63
0,97
1,55
2,5
4
6,3
9,7
500
6302
0,7
1,1
1,75
2,8
4,4
7
11
630
8002
0,8
1,25
2
3,2
5
8
12,5
800
10002
0,9
1,4
2,3
3,6
5,6
9
14
1000
12502
1,05
1,65
2,6
4,2
6,6
10,5
16,5
1250
16002
1,25
1,95
3,1
5
7,8
12,5
19,5
1600
20002
1,5
2,3
3,7
6
9,2
15
23
2000
25002
1,75
2,8
4,4
7
11
17,5
28
2500
31502
2,1
3,3
5,4
8,6
13,5
21
33
1) Values for standard tolerance grades IT01 and IT0 for basic sizes less than or equal to 500 mm are given in ISO 286 1, annex A, table 5.
2) Values for standard tolerance grades IT1 to IT5 (incl.) for basic sizes over 500 mm are included for experimental use.
3) Standard tolerance grades IT14 to IT18 (incl.) shall not be used for basic sizes less than or equal to 1 mm.
-
HOW MUCH IS THE VALUE 60% INCREASE IN TOL. VALUE FOR EVERY GRADE UP FOR A DIA GROUPEVERY 6TH GRADE GETS 100% MORE TOL VALUE
-
WHERE TO DISPOSE TOLE.TOL. CAN BE DISPOSEDABOVE BASIC DIM.BELOW BASIC DIMDISTRIBUTED ON EITHER SIDE
-
WHERE TO POSITIONPOSITIONING IS REPRESENTED BY CAPITAL LETTERS FOR HOLES A,B,HBY SMALL LETTERS FOR SHAFTS a,b,hSTD DISTANCES ARE KEPT EACH LETTER & FOR EACH DIA GROUP FROM BASIC DIM.THE DISTANCE TO THE BASIC DIM WITH LEAST VALUE IS TERMED AS FUNDEMENTAL DEVIASION; FD IS FIXED FOR A DIA-DIM COMBINATION.
-
Schematic representation of the positions of fundamental deviations
-
FITSWhen two parts to be assembled, the relation resulting from the difference between the size before assembly is called a fit.A fit is represented by 30 H 7 / g6, 30 H 7 / p6, 40 H7/h6, 40 H7k6, 40 H7p6,
-
MMC, LMC & RFSMMC - Dimension corresponding to Maximum Metal Condition (biggest shaft size or smallest hole size)LMC - Dimension corresponding to Least Metal Condition(smallest shaft or biggest hole size)RFS - Regardless of feature size
-
Actual Dimension vary from MMC limit to LMC limitWorst assembly condition exist when mating parts at MMCFunctional assembly requirements can be related to actual dimension by symbol in the drawing M