Limits Fits Tolerances
February 14, 2017 | Author: sunil_gund | Category: N/A
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Fundamentals of LIMITS, FITS and TOLERANCES
Ability needed to REPRESENT INTERPRET MANUFACTURE MEASURE
Main applications of Dimensioning and tolerances are for Holes & Shafts, Tapers, Threads, Gears, Splines etc.
35,95
± 0.125 0.025 M 0.015 M
± 0.125
0,45
59,45
0.025 M
A C0.5(BOTH SIDES)
0.025 A 0.025 M
30°
0.05 M R0,5(TYP) R4
0.6(MAX) x 45°
0 -1.0
1,5
4,15 R5
Ø73,5
Ø95,68
Ø40
Ø38.0
SCALE 5:1 REFER FORGING DRAWING NO RD 040660 03 FOR MATERIAL, HARDNESS & OTHER DETAILS
NOTE : ALL MACHINED SURFACES TO BE FREE FROM RUST AND DENT MARKS
0.02 M
Ø29.2
+0.016
M
C1.15
Ø25.25
0 -0.2
+0.1
0.0 -0.2
DETAIL AT B B
-0.350
26,58
CAD REF . : DN NGT_GSL_RD040669-04
48,3
FOR ENGG. REF.
± 0.025 0.030 M
LINEAR DIMENSION ANGULAR DIMN.
AT
ALLOWANCE
BOSS FACE
0.15 ± 0.075
FRONT FACE
0.15 ± 0.075
BORE
0.2
PN : TRANSMISSION TOOLS
DO NOT SCALE : IF IN DOUBT. REFER DESIGN OFFICE MATERIAL UNSPECIFIED APPD. MACHINING DEVIATION AS NOTED DGNR Above Upto Devn. Short side of ± mm Deg. of min 1 0.5 6 ±0.1 angle 6 30 ±0.2 Above Upto 30 120 ±0.3 10 0.1 10 120 315 ±0.5 10 50 0.2 30 315 1000 ±0.8 50 120 0.5 20 1000 2000 ±1.2 120 0.8 10
SCALE 1 :1
PART NAME: FIFTH GEAR - LAYSHAFT TOOL NAME: BLANK DRAWING(TURNED)
BY
SIGN DATE
SIZE - C TO BE USED ON TOOL NO : XXXX/Y
SHEET 1 OF 1
Different types of tolerances are 1. 2. 3. 4. 5.
Dimensional Tolerances Form Tolerances Position Tolerances Surface Roughness values Combination Tolerances
Other details shown on drawing are Material specification Special treatments if any Heat treatments Assembly condition Special notes
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 specified • Follow general engineering tolerance • IS 2102 fine, medium, course & very course • Unless otherwise specified, it is medium. • Or else it can be IT 14 VALUE, bilateral • All drawings need contain conditions on general tolerance.
1. Open tolerances or General Engineering tolerances Standards used are IS 2102 ( Part – 1) – 1993 / ISO 2768 - 1 : 1989 General Tolerances Part – 1: Tolerances for Linear and Angular dimensions without individual tolerance indications Part – 2: Geometrical Tolerances for features without individual tolerance indications Ex: 20.0, 20-f, Ø20-f H
Table 1 – Permissible deviations for linear dimensions except for broken edges (external radii and chamfer heights, see table 2) Values in millimeters Permissible deviations for basic size range
Tolerance Class
Desig Descripti nation on
0.5 up to 3
Over 3 up to 6
Over 6 up to 30
Over 30 up to 120
Over 120 up to 120
Over 400 up to 400
Over 1000 up to 2000
Over 2000 up to 4000
± 0,05
± 0,1
± 0,15
± 0,2
± 0,3
± 0,5
-
f
fine
± 0,05
m
medium
± 0,1
± 0,1
± 0,2
± 0,3
± 0,5
± 0,8
± 1,2
±2
c
coarse
± 0,2
± 0,3
± 0,5
± 0,8
± 1,2
±2
±3
±4
v
very coarse
-
± 0,5
±1
± 1,5
± 2,5
±4
±6
±8
1) 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 Class Designation Descriptio n f
fine
m
medium
c
coarse
v
very coarse
Permissible deviations for basic size range 0.5 up to 3
Over 3 up over 6 to6
± 0,2
± 0,5
±1
± 0,4
± 0,1
±2
1) 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 Class
Permissible deviations for ranges of lengths, in millimeters, of the shorter side of the angle concerned
Desig Descript up to 10 nation ion
over 10 up to 50
± 10
over 50 up to 120
over 120 up to 400
over 400
± 00 30
± 00 20’
± 00 10’
± 00 5
± 00 30’
± 00 15’
± 00 10
± 00 30’
± 00 20
F
fine
m
medium
c
coarse
± 10 30’
± 10
v
very coarse
± 30
± 20
± 10
Table 1 – General tolerances on straightness and flatness Values in millimeters
Straightness and flatness tolerances for ranges of nominal lengths
Tolerance Class up to 10
over 10 up to 30
over 30 up to 100
over 100 up to 300
over 300 up to 1000
Over 1000 up to 3000
H
0,02
0,05
0,1
0,2
0,3
0,4
K
0,05
0,1
0,2
0,4
0,6
0,8
L
0,1
0,2
0,4
0,8
1,2
1,6
Table-2 General tolerances on perpendicularity Values in millimeters
Perpendicularity tolerances for ranges of nominal lengths of the shorter side Tolerance Class up to 100
over 100 up to 300
over 300 up to 1000
over 1000 up to 3000
H
0,2
0,3
0,4
0,5
K
0,4
0,6
0,8
1
L
0,6
1
1,5
2
Table-3 – General tolerances on symmetry Values in millimeters
Symmetry tolerances for ranges of nominal lengths Tolerance Class up to 100
over 100 up to 300
H
over 1000 up to 3000
0,5
K L
over 300 up to 1000
0,6 0,6
1
0,8
1
1,5
2
Table 4 – General tolerances on circular run-out Values in mm
Tolerance class
Circular run-out tolerances
H
0,1
K
0,2
L
0,5
IS 2102 – PART – 2 • VALUES FOR – Straightness / perpendicularity / symmetry / Run out specified • Circularity - limited to diameter tolerance or run out value • Cylindricity – Limited to combined effect of CIRCULARITY& PARALLELISM. • Parallelism – Limited to Dimensional Tolerance & flatness tolerance. • Coaxiality - Limited to run out tolerance.
ISO 2768 - m • General Engg. Tole Tolerance class medium
IS 2102 – f • General Engg. Tole – class fine
ISO 2768 – mK • General Engg. Tole for dimensions Tolerance class. m • General Engg. Tole for form / position – tolerance class. K
IS 2102 – mK - E • General Engg. Tole for Dimension as per m • General Engg Tole for Form / position as per K • Enveloping dia limits -E
ISO 2768 - K • General tol. as dim not considered. • Form/position as per tol. Class K.
SPECIFIED TOLERANCE • VALUE GIVEN • VALUE AND POSISTIONAL STATUS GIVEN • STD.SYMBOLS USED.
2. Specificied tolerances Standards used IS 919 (Part – 1) – 1993 / ISO 286 – 1 : 1988 ISO System of Limits and Fits Part – 1: Bases of tolerances, Deviations and Fits Part – 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 VALUE • IS 919 / SP46 OR STD CHARTS SPECIFY. • 18 GRADES ARE SPECIFIED. VALUE IS ATTACHED TO A GRADE • IT=INTERNATIONALTOLERANCE GRADE. • AND 18 REPRESENT THE ROUGHFEST Mfg process • EVERY 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 7 • MILLING IT 6, 7, OR 8 • LAPPING IT 1, 2, 3, OR 4 • SAND CASTING IT 16, 17, 18 • PRESS WORKING IT 10, 11 OR 12 • INJ. MOULDING IT 12. 123 OR 14
Grades of tolerances obtainable manufacturing processes
by
various
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
Manufacturing Processes
IT grades
Lapping
1, 2, 3, 4
Honing
3–5
Laser beam machining
5, 6, 7
Super finishing
4–6
Grinding
4–8
Electric Discharge machining
6–7
Boring
5–9
Reaming
5–8
Broaching
5–9
Turning (Diamond tools)
4–7
Turning
7 – 12
Milling
8 – 10
Shaping
10 – 14
Drilling
11 – 14
Extrusion
9 – 12
Blanking
12 – 18
Drawing
10 – 14
Die Casting
12 – 15
Sand casting
14 – 16
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 VALUE • FOR 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 Standard tolerance grades
Basic size mm
IT12)
IT22)
IT32)
IT42)
IT52)
IT6
IT7
IT8
IT9
IT10
IT11
IT12
IT13
IT143)
IT153)
IT163)
IT173)
IT183)
1,4
Above
Up to and including
-
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
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
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
Tolerances µm
mm
3,3
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
2500
2
22
30
41
55
78
110
175
280
440
700
1100
1,75
2,8
4,4
7
11
17,5
28
3150
2
26
36
50
68
96
135
210
330
540
860
1350
2,1
3,3
5,4
8,6
13,5
21
33
2500
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 Standard tolerance grades
Basic size mm
IT12)
IT22)
IT32)
IT42)
Up to and including
Above
IT52)
IT6
IT7
IT8
IT9
IT10
IT11
Tolerances µm
-
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 Standard tolerance grades
Basic size mm
IT12
IT13
IT143)
IT153)
IT163)
IT173)
IT183)
Above
Up to and including
-
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
Tolerances mm
6
10
0,15
0,22
10
18
0,18
0,27
0,43
0,7
1,1
1,8
2,7
18
30
0,21
0,33
0,52
0,36
0,84
0,58
1,3
2,1
3,3
30
50
0,25
0,39
0,62
1
1,6
2,5
3,9
1,5
2,2
50
80
0,3
0,46
0,74
1,9
3
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
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
2
0,8
1,25
2
3,2
5
8
12,5
5,6
800
0,52
2
0,81
1,2
0,9
800
1000
0,9
1,4
2,3
3,6
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
2
2,1
3,3
5,4
8,6
13,5
21
33
3150
9
4,6
14
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 GROUP • EVERY 6TH GRADE GETS 100% MORE TOL VALUE
WHERE TO DISPOSE TOLE. • • • •
TOL. CAN BE DISPOSED ABOVE BASIC DIM. BELOW BASIC DIM DISTRIBUTED ON EITHER SIDE
WHERE TO POSITION • POSITIONING IS REPRESENTED BY CAPITAL LETTERS FOR HOLES A,B,H • BY SMALL LETTERS FOR SHAFTS a,b,h • STD 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
FITS When 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 φ 30 H 7 / g6, φ 30 H 7 / p6, φ 40 H7k6, φ 40 H7p6,
φ 40 H7/h6,
Example of general tolerances on a drawing
INTERPRETATION
FORM TOLERANCES
STRAIGHTNESS
SYMBOL -:
ZONE OF TOLERANCE :- CYLINDER
5 Tolerance frame 5.1 The tolerance requirements are shown in a rectangular frame which is divided into two or more compartments. These compartments contain, from left to right ,in the following order (see figures 3,4 and 5) : _ The symbol for the characteristic to be toleranced: _ The tolerance value in the unit used for linear dimensions. This value is preceded by the sign Φ if the tolerance zone is circular or cylindrical: _ if appropriate, the letter or letters identifying the datum feature (see figures 4 and 5)
Figures 3
Figures 4
Figures 5
5 Tolerance frame(contd) • 5.2 Remarks related to the tolerance, for example “6 holes”, “4 surfaces” or “6x” shall be written above the frame (see figures 6 and 7) • 5.3 Indications qualifying the form of the feature within the tolerance zone shall be within near the tolerance frame and may be connected by a leader line (see figures 8 and 9)
Figure 6
Figure 8
Figure 7
Figure 9
5 Tolerance frame(contd) 5.4 If it is necessary to specify more than one tolerance characteristic for a feature, the tolerance specifications are given in tolerance frames one under the other (see figure 10)
Figure 10
6 Toleranced features • The tolerance frame is connected to the toleranced feature by a leader line terminating with an arrow in the following way: • _ on the outline of the feature or an extention of the outline ( but clearly separated from the dimension line) when the tolerance refers to the line surface itself (see figures 11 and 12)
Figure11
Figure12
6 Toleranced features (contd) • _ as an extension of a dimension line when the tolerance refers to the axis or median plane defined by the feature so dimensioned (see figures 13 to 15)
Figure13
Figure14
Figure15
6 Toleranced features(contd) • _ on the axis when the tolerance refers to the axis or median plane of all features common to that axis or median plane(see figures 16,17 and 18) Figure16
Figure17
Figure18
7 Tolerance zones 7.1 The width of the tolerance zone is in the direction of the arrow of the leader line joining the tolerance frame to the feature which is tolerance, unless the tolerance value is preceded by the sign Ø (see figures 19&20).
Figure 19
Figure 20
7 Tolerance zones (contd) • 7.2 In general, the direction of the width of the tolerance zone is normal to the specified geometry of the part (see figures 21&22)
Figure 21
Figure 22
7 Tolerance zones (contd) • 7.3 The direction of the tolerance zone shall be indicated when desired not normal to the specified geometry of the part (see figures 23&24)
α α
Figure 23
Figure 24
7 Tolerance zones (contd) 7.4 Individual tolerance zones of the same value applied to several separate features can be specified as shown in figures 25&26.
Figure 25
Figure 26
7 Tolerance zones (contd) 7.5 Where a common tolerance zone is applied to several separate features, the requirement is indicated by the words “common zone” above the tolerance frame (see figures 27&28).
3XA COMMON ZONE
COMMON ZONE
A
Figure 27
A
A
Figure 28
8 Datums 8.1 When a tolerance feature is related to a datum, this is generally shown by datum latter which defines the datum is repeated in the tolerance frame. To identify the datum, a capital letter enclosed in a frame is connected to a solid or blank datum triangle (see figures 29&30).
Figure 29
Figure 30
8.2
The Datum triangle with the datum letter is placed: -On the outline of the feature or an extension of the out line (but clearly separated from the dimension line), when the datum feature is the line or surface itself (see figures 31)
Figure 31
- as an extension of the dimension line when the datum feature is the axis or median plane (see figures 32 to 34). NOTE - If there is insufficient space for two arrows, one of them may be replaced by the datum triangle (see figures 33 and 34).
on the axis or median plane when the datum is : a) the axis or median plane of a single feature (for example a cylinder); b) the common axis or plane formed by two features (see figure 35).
8.3 If the tolerance frame can be directly connected with the datum feature by a leader line, the datum letter may be omitted (see figures 36 and 37).
8.4 A single datum is identified by a capital letter (see figure 38). A common datum formed by two features is identified by two datum letter separated by a hyphen (see figure 39). If the sequence of two or more datum features is important the datum letters are placed in different compartments (see figure 40), where the sequence from left to right shows the order of priority.
If the sequence of two or more datum features is not important the datum letters are indicated in the same compartment (see figure 41).
9 Restrictive specifications 9.1 If the tolerance is applied to a restricted length, lying anywhere, the value of this length shall be added after the tolerance value and separated from it by an oblique stroke. In the case of a surface, the same indication is used. This means that the tolerance applies to all lines of the restricted length in any position and any direction (see figure 42).
9.2 If a smaller tolerance of the same type is added to the tolerance on the whole feature, but restricted over a limited length, the restrictive tolerance shall be indicated in the lower compartment (see figure 43). 9.3 If the tolerance is applied to a restricted part of the feature only, this shall be dimensioned as shown in figure 44.
9.4 If the datum is applied to a restricted part of the datum feature only, this shall be dimensioned as shown in figure 45. •9.5 Restrictions to the form of the feature within the tolerance zone are shown in 5.3.
Theoretically exact dimensions If tolerances of position or of profile or of angularity are prescribed for a feature, the dimensions determining the theoretically exact position, profile or angle respectively, shall not be toleranced. These dimensions are enclosed, for example The corresponding actual dimensions of the part are subject only to the position tolerance, profile tolerance or angularity tolerance specified within the tolerance frame (see figures 46 and 47). Figure 46 Figure 47 .
• Projected tolerance zone In some causes the tolerances of orientation and location shall apply not to the feature itself but to the external projection of it. Such projected tolerance zones are to be indicated by the symbol (see figure 48). Maximum material condition The indication that the tolerance value applies at the maximum material condition is shown by the symbol placed after: The tolerance value (see figure 49);
Figure 48
Figure 49
The datum letter (see figure 50); Or both (see figure 51);According to whether the maximum material principle is to be applied respectively to the toleranced feature. the datum feature or both.
Figure 50 Figure 51
• Definitions of tolerances • The various geometrical tolerances are defined with their tolerance zones in the following pages. In all the illustrations of the definitions only those deviations are shown with which the definitions deal. • Where required for functional reasons, one or more characteristics will be toleranced to define the geometrical accuracy of a feature. When the geometrical accuracy of a feature is defined by a certain type of tolerance, other deviations of this feature in some cases will be controlled by this tolerance (for example, straightness deviation is limited by parallelism tolerance). Thus it would rarely be necessary to symbolize all of these characteristics, since the other deviations are included on the zone of tolerance defined by the symbol specified.
FLATNESS
SYMBOL -:
ZONE OF TOLERANCE :- TWO PARALLEL PLANES
CIRCULARITY
SYMBOL -:
ZONE OF TOLERANCE :- TWO COPLANAR CONCENTRIC CIRCLES
Circularity The permissible deviation of the diameter is indicated directly on the drawing; the general tolerance on circularity is equal to the numerical value of the diameter tolerance.
EXAMPLE 1
Circularity The general tolerance in accordance with the indication ISO 2768-mK apply. The permissible deviations for the diameter of 25mm are ±0.2mm. These deviations lead to the numerical value of 0.4mm which is greater than the value of 0.2mm given in table 4; the value of 0.2mm therefore, applies for the circularity tolerance.
EXAMPLE 2
CYLINDRICITY
SYMBOL -:
ZONE OF TOLERANCE :- TWO COAXIAL CYLINDERS
PROFILE OF ANY LINE
SYMBOL -:
ZONE OF TOLERANCE :- TWO PROFILE LINES
PROFILE OF ANY SURFACE
SYMBOL -:
ZONE OF TOLERANCE :- TWO PROFILED PLANES
POSITION TOLERANCES
Other symbols
PARALLELISM
SYMBOL -:
ZONE OF TOLERANCE :- CYLINDER
Parallelism Depending on the shapes of the deviations of the features, the parallelism deviation is limited by the numerical value of the size tolerance (see figure B.3) or by the numerical value of the straightness or flatness tolerance (see figure B.4)
PARALLELISM TOLERANCE PARALLELISM TOLERANCE OF A LINE WITH REFERENCE TO A DATUM SURFACE Definition of the tolerance zone The tolerance zone is limited by two parallel planes a distance t apart and parallel to the datum surface
Indication and Interpretation The axis of the hole shall be contained between two planes 0.01 apart and parallel to the datum surface B
PARALLELISM TOLERANCE OF A SURFACE WITH REFERENCE TO A DATUM LINE Definition of the tolerance zone The tolerance zone is limited by two parallel a distance t apart and parallel to the datum line.
Indication and Interpretation The tolerance surface shall be contained between two planes 0.1 apart and parallel to the datum axis of the hole
PARALLELISM TOLERANCE OF A SURFACE WITH REFERENCE TO A DATUM SURFACE Definition of the tolerance zone
Indication and Interpretation
The tolerance zone is limited by The tolerance surface shall be contained two parallel planes a distance t between two parallel planes 0.01 apart and apart and parallel to the datum parallel to the datum surface D surface All the points on tolerance surface in a length of 100, placed anywhere on this surface, shall be contained between two parallel planes 0.01 apart and parallel to the datum surface A.
PERPENDICULARITY
SYMBOL -:
ZONE OF TOLERANCE :- TWO PARALLEL PLANES PERPENDICULAR TO DATUM SURFACE
PERPENDICULARITY TOLERANCE PERPENDICULARITY TOLERANCE REFERENCE TO A DATUM LINE Definition of the tolerance zone The tolerance zone when projected in a plane is limited by two parallel straight lines a distance t apart and perpendicular to the datum line
OF
A
LINE
WITH
Indication and Interpretation The axis of the inclined hole shall be contained between two parallel planes 0.06 apart and perpendicular to the axis of the horizontal hole A(datum line)
PERPENDICULARITY TOLERANCE OF A LINE WITH REFERENCE TO A DATUM SURFACE The tolerance zone is limited by a parallelepiped of section t1 xt2 and perpendicular to the datum plane if the tolerance is specified in two directions perpendicular to each other
The axis of the cylinder shall be contained in a parallelepiped tolerance zone of 0.1x0.2, which is perpendicular to the datum surface
PERPENDICULARITY TOLERANCE OF A LINE WITH REFERENCE TO A DATUM SURFACE The tolerance is limited by a cylinder of diameter t perpendicular to the datum plane if the tolerance value is preceded by the sign Ø
The axis of the cylinder to which the tolerance frame is connected shall be contained in a cylindrical zone of diameter 0.01 perpendicular to the datum surface A
PERPENDICULARITY TOLERANCE OF A SURFACE WITH REFERENCE TO A DATUM LINE DEFINITION OF THE TOLARANCE ZONE
The tolerance zone is limited by two parallel planes a distance t apart and perpendicular to the datum line.
INDICATION AND INTERPRETATION
The tolerance piece of the piece shall be contained between two parallel planes 0.08 apart and perpendicular to the axis A (datum line).
PERPENDICULARITY TOLERANCE OF A SURFACE WITH REFERENCE TO A DATUM SURFACE DEFINITION OF THE TOLARANCE ZONE
The tolerance zone is limited by two parallel planes a distance t apart and perpendicular to the datum surface.
ANGULARITY
INDICATION AND INTERPRETATION
The toleranced surface shall be contained between two parallel planes0.08 apart and perpendicular to the horizontal datum surface A.
SYMBOL -:
a
ZONE OF TOLERANCE -: TWO PARALLEL PLANES INCLINED 60 DEGREE TO DATUM SURFACE.
PERPENDICULARITY TOLERANCE OF A LINE WITH REFERENCE TO A DATUM SURFACE The tolerance zone when projected in a plane is limited by two parallel straight lines a distance t apart and perpendicular to the datum plane if the tolerance is specified only in one direction
The axis of the cylinder, to which the tolerance frame is connected, shall be contained between two parallel planes 0.1 apart, perpendicular to the datum surface
ANGULARITY TOLERANCE ANGULARITY TOLERANCE OF A LINE WITH REFERENCE TO A DATUM LINE DEFINITION OF THE TOLARANCE ZONE
a) Line and datum line in the same plane. The tolerance zone when projected in a plane is limited by two parallel straight lines a distance t apart and inclined at the specified angle to the datum line.
INDICATION AND INTERPRETATION
The axis of the hole shall be contained between two parallel straight planes 0.08 apart which are inclined at 60° to the horizontal A-B (datum line).
DEFINITION OF THE TOLARANCE ZONE
b) Line and datum line in different planes If the considered line and the datum line are not in the same plane, the tolerance zone is applied to the projection of the considered line on the plane containing the datum line and parallel to the considered line.
INDICATION AND INTERPRETATION
The axis of the hole projected on a plane containing the datum axis shall be contained between two parallel straight lines
ANGULARUTY TOLERANCE OF A LINE WITH REFERANCE TO A DATUM SURFACE DEFINITION OF THE TOLERANCE ZONE
The tolerance zone when projected in a plane is limited by two parallel straight lines a distance t apart and inclined at the specified angle to the datum surface.
INDICATION AND INTERPRETATION
The axis of the hole shall be contained between two parallel planes 0.08 apart which are inclined at 60° to the surface A (datum surface)
ANGULARITY TOLERANCE OF A SURFACE WITH REFERENCE TO A DATUM LINE DEFINITION OF THE TOLERANCE ZONE
The tolerance zone is limited by two parallel planes a distance t apart and inclined at the specified angle to the datum line.
INDICATION AND INTERPRETATION
The inclined surface shall be contained between two parallel planes 0.1 apart which are inclined at 75° to the axis A (datum line).
ANGULARITY TOLERANCE OF A SURFACE WITH REFERENCE TO A DATUM SURFACE DEFINITION OF THE TOLERANCE ZONE
The tolerance zone is limited by two parallel planes a distance t apart and inclined at the specified angle to the datum surface.
INDICATION AND INTERPRETATION
The inclined surface shall be contained between two parallel planes 0.1 apart which are inclined at 40° to the surface A (datum surface).
POSITION
SYMBOL -:
ZONE OF TOLERANCE :- CYLINDER
POSITIONAL TOLERANCE POSITIONAL TOLERANCE OF A POINT DEFINITION OF THE TOLERANCE ZONE
The tolerance zone is limited by a circle of diameter t, the centre of which is in the theoretically exact position of the considered point.
INDICATION AND INTERPRETATION
The actual point of intersection shall lie inside a circle of 0.3 diameter ,the centre of which coincides with the theoretically exact position of the considered point of intersection.
Position tolerance of a line Definition of the tolerance zone
Indication and interpretation
The tolerance zone is limited by two parallel straight lines a distance t apart and disposed symmetrically with respect to the theoretically exact position of the considered line if the tolerance is specified only in one direction.
Each of the lines shall be contained between two parallel straight lines 0.05 apart which are symmetrically disposed about the theoretically exact position of the considered line, with reference to the surface A (datum plane).
Definition of the tolerance zone
The tolerance zone is limited by a parallelepiped of section t1x t2 the axis of which is in the theoretically exact position of the considered line if the tolerance is specified in two directions perpendicular to each other.
Indication and interpretation
Each of the axes of the eight holes shall be contained within a parallelepipedic zone of width 0.05 in the horizontal and 0.2 in the vertical direction and the axis of which is in the theoretically exact position of the considered hole.
Definition of the tolerance zone
The tolerance zone is limited by a cylinder of diameter ‘t’ the axis of which is in the theoretically exact position of the considered line if the tolerance value is preceded by the sign ø
Definition of the tolerance zone
The tolerance zone is limited by a cylinder of diameter ‘t’ the axis of which is in the theoretically exact position of the considered line if the tolerance value is preceded by the sign ø
Indication and interpretation
The axis of the hole shall be contained within a cylindrical zone of diameter 0.08 the axis of which is in the theoretically exact position of the considered line, with reference to the surfaces A and B (datum planes).
Indication and interpretation
Each of the axes of the eight holes shall be contained within a cylindrical zone of diameter 0.1 the axis of which is in the theoretically exact position of the considered hole.
Position tolerance of a flat surface or a median plane Definition of the tolerance zone
The tolerance zone is limited by two parallel planes a distance t apart and disposed symmetrically with respect to the theoretically exact position of the considered surface.
COAXIALITY
Indication and interpretation
The inclined surface shall be contained between two parallel planes which are 0.05 apart and which are symmetrically disposed with respect to the theoretically exact position of the considered surface with reference to the surface A(datum plane)and the axis of the datum cylinder B (datum line)
SYMBOL -:
ZONE OF TOLERANCE :- CYLINDER
Concentricity tolerance of a point Definition of the tolerance zone
The tolerance zone is limited by a circle of diameter t the center of which coincides with the datum point
Indication and interpretation
The centre of the circle , to which the tolerance frame is connected, shall be contained in a circle of diameter 0.01 concentric with the centre of the datum circle A.
Coaxiality tolerance of an axis Definition of the tolerance zone
The tolerance zone is limited by a cylinder of diameter I, the axis of which coincides with the datum axis if the tolerance value is preceded by the sign ø.
Indication and interpretation
The axis of the cylinder, to which the tolerance frame is connected, shall be contained in a cylindrical zone of diameter 0.08 coaxial with the datum axis A-B.
SYMMETRY
SYMBOL -:
ZONE OF TOLERANCE :- TWO PARALLEL PLANES
Symmetry tolerance of a median plane Definition of the tolerance zone
The tolerance zone is limited by two parallel planes a distance t apart and disposed symmetrically to the median plane with respect to the datum axis or datum plane.
Indication and interpretation
The median plane of the slot, shall be contained between two parallel planes, which are 0.08 apart and symmetrically disposed about the median plane with respect to the datum feature A.
Symmetry– Examples
For some tolerance zones (for example, for straightness of a line or axis in one direction only) there are two possible methods, of graphical representation: By two parallel planes a distance ‘t’ apart (see figure 52); By two parallel straight lines a distance ‘t’ apart (see figure 53); Figure 52 shows a three-dimensional representation, figure 53 its projection in a plane.
There is no difference in the meaning of the two representations (such a tolerance does not restrict the deviation in any direction perpendicular to the arrow). The simpler method as shown in figure 53 is normally used in this International Standard.
Figure 52
Figure 53
CIRCULAR RUNOUT
SYMBOL -:
ZONE OF TOLERANCE :- TWO COPLANAR CONCENTRIC CIRCLES
TOTAL RUNOUT
SYMBOL -:
ZONE OF TOLERANCE :- TWO COAXIAL CYLINDERS
TOTAL RUN-OUT TOLERANCE TOTAL AXIAL RUN-OUT TOLERANCE
INDICATION AND INTERPRETATION
The tolerance zone is limited by two parallel planes a distance t apart and perpendicular to the datum axis.
The total axial run-out shall not be greater than 0.1 at any point on the surface during several revolutions about the datum axis D and with relative radial movement between the measuring instrument and the part. With relative movement the measuring instrument or the work piece shall be guided along a line having the theoretically perfect form of the contour and being in correct position to the datum axis.
MMC, LMC & RFS MMC - 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 limit • Worst assembly condition exist when mating parts at MMC • Functional assembly requirements can be related to actual dimension by symbol M in the drawing
Ø0.4 M
0
Ø12 -0.2
M12
−
Virtual size
Ø0.4 Ø12
Ø0.6
Ø12
Ø12
Ø11.8
Actual Local Sizes
D
Virtual size
Tolerance zone
Ø12.4
Ø12.4
Tolerance zone
Ø11.8
Ø11.8
Actual Local Sizes
M
Virtual Condition normal to Datum Plane D
Datum Plane D A1 to A3 = actual Local sizes =19.9 ...20 (maximum material size = Ø20) G
= virtual size = Ø20.2
Øt
= orientational tolerance zone = 0.2 ..0.3
ØG
A3
Øt
A2
D
A1
Ø0.2 M
0
⊥
Ø20 -0.1
D
Ø0.2
Ø20
Ø20
Ø20
ØG=Ø20.2
Actual Local Sizes
Ø0.3
Datum Plane D
Ø19.9
Ø19.9
Ø19.9
ØG=Ø20.2
Actual Local Sizes Datum Plane D
Dimensioning of profiles
70 °
0
25
β
0°
20°
40°
60°
80°
100°
a
50
52.5
57
63..5
70
74.5
120°210° 76
FOLLWER
230°
260°
280°
300°
320°
340°
75
70
65
59.5
55
52
0.1
0°
12 0°
0°
12
12
0° 12
0 Ø8
R8
R8
120°
a) Indication on the drawing
120°
b) Interpretation
21
28
35
19.5
21
14
17
7 10
A) Indication on the drawing
13
14 8
35
14
28
21
7
21
19.5
14
17
7 10
13
14
0.1
R5
SR 80
80 SR
R5
230 270
.1 Ø0
B) Interpretation
180
14 7
8
0.1 A-B
500
A) Indication on the drawing
230
270
500
B) Interpretation
Packing ring of a pump 0.01/5 NOT CONVEX
Ø22H7 Ø44H7
0.03
R5
180
80 SR
80 SR
R5
Friction wheel 0.02 A 0.01 A
Ø36 H8
0.04 A
0.01 A
A
Arbor for milling cutter
+0,18 0.05 A
0.01 A
8.2H11
1520-0
0.1 B
Ø
0.01 A
A
A B
0.01
0.005
0.02 AB 0.01 AB
0.008
B A
Ø11H7
Ø11H7
Ø80
0.005 0.008 B
A
B
FIG. 5
0.025 A 39
Ball bearing inner ring
Roller
25
Bearing housing
0.02 A
X 0.1
A
35 34
30 25
Ø47M6(
58 57
)
A
0.03
A
0.03
A
SECTION XX
CAM
Ø6H7 Ø18
A
5E9
0.03 A
0.02 A
Cam shaft 0.02 AB 0.02
CL OF CAM LOBE
0.02 C 0.08 AB 0.02 AB R4
R15.75
11°30"
R4 C
R25.75
R16
9,015 9 A
B
0.01
DISC 0.05
A B
40±0.1 3x45°±2°
+0.06 8 HOLES EQUISPACED Ø11 -0
X
A B
A
0 -0.05 160
70
A B 0.05 A
0.02 Ø9
0.02
Ø142
+0.02 0
25,5
11
B
Ø108
0.01
10
l
3 19
8 HOLES EQUISPACED EQUISPACED M8 8 HOLES .M8
X
0.2 A B
22°10'
0°
10 mi n
SECTION XX
Drilling Jig 0.1
Φ120
A
Ø120
30°
12 HOLES H7
0.02 A
f A
Ød
Ø b
g
A
C
PART NO:
DIM ENSIONS
TOLERANCES
b
c
d
e
f
G
1
15
7
8h8
47
0.005
0.005
2
20
8
10h 8
58
0.01
0.008
3
30
10
15h 9
70
0.02
0.01
4
50
12
25h 9
112
0.05
0.015
Drawing in which dimensions are shown in tabular form
Tolerance Analysis
Dimension based on functional Importance • Dimension ( Series, parallel or progressive ) is done on the basis of functional importance. Process Planning ( for the component shown ) depends on the way of dimensioning.
PROCESS PLANNING Oper. No.
Operation
1000
Facing to 55 mm length
1005
Turning to Ø20 whole length
1010
Turning to Ø8 till 35mm
Sketch
Same component can be machined another way also
IMPORTANCE OF FUNCTIONAL DIMENTIONS • Do not give ending dimension in the drawing • Ending dimension gets cumulative tolerance, whether add or subtract • Way of dimensioning will make the manufacturing process
Examples 35±0.1 and 20±0.05
So 55 will be 55±0.15 T total = Some of individual Tolerances 35±0.1 Tolerance = 0.2 20±0.05 Tolerance = 0.1 55±0.15 Tolerance = 0.3 So T 55 = T 35 + T 20 i.e 0.3 = 02 + 0.1
Tolerance analysis c1 c2
C C
b1 b2
a1 a2
A
B A
B
Tolerance analysis
Example 8
C+c2 = ( A+a2 ) + (B+b2) So c2 = a2 + b2 C2 C1
Rule :- C = (A+B)
( a2 + b2 ) ( a1 + b1 )
and 3
+0.2 +0.1
So 11 Now
-0.1 -0.3
( +0.2 ) + ( -0.1 ) ( +0.1) + ( -0.3 )
= 11 +0.1
- 0.2
Tol8 = 0.1
Tol3 = 0.2 , Tol11 = 0.3
∴
Tol11 = Tol8 + Tol3
-0.2
-0.05
12 +0.1+ 4 ±0.1 + 3 -0.1
∴ 19
( +0.1) + (+0.1) + (+0.1) ( -0.2 ) + (- 0.1) + (+ 0.05)
Tol 12 = 0.3
,
Tol 3 = 0.15 ,
= 19
+0.3 -0.35
Tol 4 = 0.2 Tol 19 = 0.65
a2
AAa1
EXAMPLE 1 - 0.1
b2
c1
CCc2
12 - 0.3 - 8 ±0.1 = 4
BBb1
0.00 - 0.40
(- 0.1) – (- 0.1 )
C 12
+ 0.2 + 0.1
∴ 18
+4
( a2 – b1 ) ( a1 – b2 )
±0.1
+3
a2
b2
1
1
i.e. 4(- 0.3) – (+0.1) ∴ Tol 12 = 0.2 Tol 8 = 0.2 Tol 4 = 0.4
= Aa - B b
- 0.05 + 0.1
-5
+ 0.2 + 0.1 + 0.1 + 0.1 + 0.2 + 0.1 – 0.1 – 0.05 – 0.1 + 0.1
±0.1
+4
= 18
+ 0.2 + 0.1
+ 0.70 - 0.05
2 T12 + T4 + T3 + T4 – T5 = T18 i.e.
0.1 + 0.2 + 0.15 + 0.1 – 0.2 = 0.75
Series dimensioning not preferred
Parallel dimensions are most preferred , since Tolerance get added in series dimensioning
Theory of datum change Counter bore height 22±0.1 - 18±0.05 = 4±0.15 To get the shank height (reverse) 22±0.1 - 4±0.15 = 18±0.25 So, 18±0.25 , The Tolerance exceeds
Theory of datum change Check whether Datum change is possible 18±0.05 = 22±0.1 – 4 Datum change is not possible, so redesign the Tolerance X2 values of 22 and 4 X1 i.e to get 18±0.05 change the change the Tolerance of 22 and 4 Take
Tol22 = 0.06
and Tol4 = 0.04
Hence Tol18 = 0.06 + 0.04 = 0.1 ∴
Values are 22±0.03 and 4±0.02
Ø0.1
D- 0.5
⊥
A
Ø20
(Ø6H8) c H8
ØAH8
- 0.1 P Ø14 H8(25µ)
± 0.1 E
A ± 0.05 B 40 60
± 0.02 E
± 0.02 F
F
LOCATION
CAN WE CHANGE DATUM ?
80
112
20
- 0.05
± 0.05
X1 12 X2 ± 0.1 (80 )
0.5
ABC
15
15
8x
8x
105
105
R
R
SR
SR
SØ
SØ
CR
NONE
ST
NONE
or
or
* *
0.5
NONE
May be filled or not filled
ABC
± 0.1
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