Limits Fits Tolerances

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