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.

R0,5(TYP)

4,15 1,5

0,45

30°

0.6(MAX) x 45°R4

0-1.0

C0.5(BOTH SIDES)

M

Ø38

.0 0 -0

.2

Ø29

.2+0

.016

35,95± 0.125

59,45± 0.125

A

0.025 M

0.025 A0.025 M

0.025 M0.015 M

R5

Ø40

Ø73

,5

Ø95

,68

0.0

-0.2

0.05 M

0.02 M

48,3± 0.025

26,58-0.350

0.030 M

Ø25

.25

+0.1

C1.15B

DETAIL AT BSCALE 5:1

REFER FORGING DRAWING NO RD 04066003

FOR MATERIAL, HARDNESS & OTHER DETAILS

NOTE : ALL MACHINED SURFACES TO BE FREE FROM RUST AND DENT MARKS

CAD REF . : DN NGT_GSL_RD040669-04 PN : TRANSMISSION TOOLSDO NOT SCALE : IF IN DOUBT. REFER DESIGN OFFICE

APPD.DGNRBY DATESIGN

SIZE - CTO BE USED ON

TOOL NO : XXXX/Y

SHEET 1 OF 1

SCALE 1 :1TOOL NAME: BLANK DRAWING(TURNED)

PART NAME: FIFTH GEAR - LAYSHAFT

UNSPECIFIED MACHINING DEVIATION

MATERIAL AS NOTED

LINEAR DIMENSION ANGULAR DIMN.

Above Upto Devn.0.5 6 ±0.1

±0.230630 120 ±0.3

±0.5315120315 1000 ±0.8

±1.220001000

Short side of angle ± mm

Deg. of min 1

Above Upto1050

1201205010

0.1 103020100.8

0.50.2

FOR ENGG. REF.

AT ALLOWANCE

0.15 ± 0.075

0.15 ± 0.075

0.2BORE

FRONT FACE

BOSS FACE

Different types of tolerances are

1. Dimensional Tolerances2. Form Tolerances3. Position Tolerances4. Surface Roughness values5. Combination Tolerances

Other details shown on drawing are

Material specificationSpecial treatments if anyHeat treatmentsAssembly conditionSpecial 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 tolerancesStandards used are IS 2102 ( Part – 1) – 1993 / ISO 2768 - 1 : 1989

General 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, 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

1) For nominal sizes below 0,5 mm, the deviations shall be indicated adjacent to the relevant nominal size (s).

± 8± 6± 4± 2,5± 1,5± 1± 0,5-very coarse

v

± 4± 3± 2± 1,2± 0,8± 0,5± 0,3±0,2

coarsec

± 2± 1,2± 0,8± 0,5± 0,3± 0,2± 0,1±0,1

mediumm

-± 0,5± 0,3± 0,2± 0,15± 0,1± 0,05± 0,05finef

Over2000up to4000

Over1000up to2000

Over400

up to400

Over120

up to120

Over30

up to120

Over6

up to30

Over3

up to6

0.5up to

3Descripti

onDesignation

Permissible deviations for basic size rangeTolerance Class

Table 2 – Permissible deviations for broken edges ( external radii and chamfer heights)


1) For nominal sizes below 0.5 mm, the deviations shall be indicated adjacent to the relevant nominal size(s).

very coarse

v ± 2± 0,1± 0,4coarsecmediumm

± 1± 0,5± 0,2finef

over 6Over 3 up to6

0.5 up to 3Description

Designation

Permissible deviations for basic size rangeTolerance Class

Table 3 – Permissible deviations of angular dimensions

± 00 20± 00 30’± 10± 20± 30very coarse

v± 00 10± 00 15’± 00 30’± 10± 10 30’coarsec

mediumm± 00 5± 00 10’± 00 20’± 00 30± 10fineF

over 400

over 120 up to 400

over 50 up to 120

over 10 up to 50

up to 10Description

Designation

Permissible deviations for ranges of lengths, in millimeters,

of the shorter side of the angle concernedTolerance Class

Table 1 – General tolerances on straightness and flatness


Tolerance Class

Straightness and flatness tolerances for ranges of nominal lengths

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 perpendicularityValues in millimeters

Tolerance Class

Perpendicularity tolerances for ranges of nominal lengths of the shorter side


over 300up to 1000

over 1000up 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

Tolerance Class

Symmetry tolerances for ranges of nominal lengths


over 300up to 1000

over 1000up to 3000

H 0,5

K 0,6 0,8 1

L 0,6 1 1,5 2

Table 4 – General tolerances on circular run-outValues 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 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 SPECIFICATIONNeed 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 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

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)

Above Up to and including

Tolerances µm 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.


Standard tolerance grades Basic size mm IT12) IT22) IT32) IT42) IT52) IT6 IT7 IT8 IT9 IT10 IT11

Above Up to and

including

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.


Standard tolerance grades Basic size mm 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 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 H7/h6,φ 40 H7k6, φ 40 H7p6,

Example of general tolerances on a drawing

INTERPRETATION

FORM TOLERANCES

STRAIGHTNESSSTRAIGHTNESS

ZONE OF TOLERANCE :- CYLINDER

SYMBOL :-

5 Tolerance frame5.1 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 5

Figures 4

Figures 3

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 7

Figure 8 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)

Figure15

Figure14

Figure13

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)

Figure18Figure17

Figure16

7 Tolerance zones7.1 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

7.5 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).

Figure 27 Figure 28

A

COMMON ZONE

AA

COMMON ZONE3XA

7 Tolerance zones (contd)

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.

.

Figure 46Figure 47

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).

• 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);

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 48

Figure 51

Figure 49

Figure 50

• 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.

FLATNESSFLATNESS

ZONE OF TOLERANCE :- TWO PARALLEL PLANES

SYMBOL :-

CIRCULARITYCIRCULARITY

ZONE OF TOLERANCE :- TWO COPLANAR CONCENTRIC CIRCLES

SYMBOL :-

CircularityThe 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

CYLINDRICITYCYLINDRICITY

ZONE OF TOLERANCE :- TWO COAXIAL CYLINDERS

SYMBOL :-

PROFILE OF ANY LINEPROFILE OF ANY LINE

ZONE OF TOLERANCE :- TWO PROFILE LINES

SYMBOL :-

PROFILE OF ANY SURFACEPROFILE OF ANY SURFACE

ZONE OF TOLERANCE :- TWO PROFILED PLANES

SYMBOL :-

POSITION TOLERANCES

Other symbols

PARALLELISMPARALLELISM


SYMBOL :-

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)

Definition of the tolerance zone

PARALLELISM TOLERANCE OF A LINE WITH REFERENCE TO A DATUM SURFACE

Indication and Interpretation

The tolerance zone is limited by two parallel planes a distance t apart and parallel to the datum surface

The axis of the hole shall be contained between two planes 0.01 apart and parallel to the datum surface B

PARALLELISM TOLERANCE


PARALLELISM TOLERANCE OF A SURFACE WITH REFERENCE TO A DATUM LINE


The tolerance zone is limited by two parallel a distance t apart and parallel to the datum line.

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

The tolerance zone is limited by two parallel planes a distance t apart and parallel to the datum surface

The tolerance surface shall be contained between two parallel planes 0.01 apart and parallel to the datum surface D

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.


PERPENDICULARITYPERPENDICULARITY

ZONE OF TOLERANCE :- TWO PARALLEL PLANES PERPENDICULAR TO DATUM SURFACE

SYMBOL :-

PERPENDICULARITY TOLERANCEPERPENDICULARITY TOLERANCE OF A LINE WITH REFERENCE TO A DATUM LINE

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

Definition of the tolerance zone 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


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 INDICATION AND INTERPRETATION

The tolerance zone is limited by two parallel planes a distance t apart and perpendicular to the datum line.

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


The tolerance zone is limited by two parallel planes a distance t apart and perpendicular to the datum surface.

The toleranced surface shall be contained between two parallel planes0.08 apart and perpendicular to the horizontal datum surface A.

ANGULARITYANGULARITY

ZONE OF TOLERANCE :- TWO PARALLEL PLANES INCLINED 60 DEGREE TO DATUM SURFACE.

SYMBOL :-

a


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 OF A LINE WITH REFERENCE TO A DATUM LINE


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.

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).

ANGULARITY TOLERANCE


b) Line and datum line in different planesIf 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.

The axis of the hole projected on a plane containing the datum axis shall be contained between two parallel straight lines

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.

ANGULARUTY TOLERANCE OF A LINE WITH REFERANCE TO A DATUM SURFACE

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)

DEFINITION OF THE TOLERANCE ZONE INDICATION AND INTERPRETATION

The tolerance zone is limited by two parallel planes a distance tapart and inclined at the specified angle to the datum line.

ANGULARITY TOLERANCE OF A SURFACE WITH REFERENCE TO A DATUM LINE

The inclined surface shall be contained between two parallel planes 0.1 apart which are inclined at 75° to the axis A (datum line).


The tolerance zone is limited by two parallel planes a distance t apart and inclined at the specified angle to the datum surface.

ANGULARITY TOLERANCE OF A SURFACE WITH REFERENCE TO A DATUM SURFACE

The inclined surface shall be contained between two parallel planes 0.1 apart which are inclined at 40° to the surface A (datum surface).


POSITIONPOSITION


SYMBOL :-

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.

POSITIONAL TOLERANCE OF A POINT

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.


POSITIONAL TOLERANCE

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 Indication and interpretation

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.

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.


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

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).


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

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 planeDefinition of the tolerance zone Indication and interpretation

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.

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)

COAXIALITYCOAXIALITY


SYMBOL :-

Concentricity tolerance of a point


The tolerance zone is limited by a circle of diameter t the center of which coincides with the datum point

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


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.

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.

SYMMETRYSYMMETRY

ZONE OF TOLERANCE :- TWO PARALLEL PLANES

SYMBOL :-

Symmetry tolerance of a median plane


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.

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

Figure 52

Figure 53

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.

CIRCULAR RUNOUTCIRCULAR RUNOUT

ZONE OF TOLERANCE :- TWO COPLANAR CONCENTRIC CIRCLES

SYMBOL :-

TOTAL RUNOUTTOTAL RUNOUT

ZONE OF TOLERANCE :- TWO COAXIAL CYLINDERS

SYMBOL :-

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 in the drawing

M

M12

0 -0.2

Ø12

− Ø0.4 M

Ø12

.4

Ø0.4

Ø12 Ø12 Ø12

Actual Local Sizes

Tolerance zoneVirtual size

Tolerance zone

Ø0.6

Ø11.8

Ø12

.4

Virtual size

Ø11.8Ø11.8

Actual Local Sizes

D

D

Ø20

0 -0.1

D⊥ Ø0.2

M

M

ØG

Virtual Conditionnormal to Datum Plane D

Datum Plane D

Øt

A1

A2

A3

A1 to A3 = actual Local sizes =19.9 ...20 (maximum material size = Ø20)

G = virtual size = Ø20.2Øt = orientational tolerance zone = 0.2 ..0.3

Ø19.9Ø19.9Ø19.9

Actual Local SizesDatum Plane D

Ø0.

3Ø

0.2

Actual Local Sizes

Datum Plane D

ØG=Ø20.2

Ø20Ø20Ø20ØG=Ø20.2

Dimensioning of profiles

70°

FOLLWER25

0

β 0° 20° 40° 60° 80° 100°120°-

210°230° 260° 280° 300° 320° 340°

a 50 52.5 57 63..5 70 74.5 76 75 70 65 59.5 55 52

120°

120°120°

120°

120°

120°

a) Indication on the drawing b) Interpretation

R8

0.1

Ø80

R8

28

7 8

19.5

17

10 13

14 14 7 2114

21

1087

0.1 A-B

35 1414 7

Ø0.1

21

17

13

19.5

2814 21 35

A) Indication on the drawing B) Interpretation

270

R5

230

500

SR80SR80 R5

180

0.1

A) Indication on the drawing

R5

270

SR80

R5

500

230

SR80

180

B) Interpretation

Ø44

H7

0.01/5 NOT CONVEX

0.03

Packing ring of a pump

Ø22

H7

Ø36

H8

A

0.01 A

0.01 A

0.02 A

0.04 A

Friction wheel0.

1B

A

20+0,18-0

8.2H

11

Ø

0.05 A

A

0.01 A

0.01 A

Arbor for milling cutter

B

15

39

0.008

0.005

A

Ø80

0.01 AB

FIG. 5

Ø11

H7

B

0.02 AB

Ø11

H7

A

0.01

B

0.025 A

0.008 B0.005

Ball bearing inner ring Roller

30

X

0.1 A

0.03 A

0.03 A

SECTION XX

2525

25

A

()

0.02 A

Ø47

M658 57

35 34

Bearing housing

Ø6H7

Ø18 0.02 A

A

0.03 A

5E9

CAM

9,0159R25.75 C

A0.01

B

0.02 AB

R16

0.02 CCL OF CAM LOBE

R15.75

R4

R4

0.02

0.02 AB

0.08 AB

11°30"

Cam shaft

10 min19

SECTION XX

11

0.05 A

Ø10

8

8 HOLES EQUISPACED Ø11

0.01 A B

0.02 A B

+0.06-0

0.2 A B8 HOLES EQUISPACED M8

40±0.1

70 160

25,5

Ø9

30°l

0.02

+0.0

20

103x45°±2°

0 -0.0

5

BA

Ø14

2

22°10'

X

X

0.05 A B

DISC

8 HOLES EQUISPACED .M8

Ø120

Drilling Jig 0.1

30°

0.02 A

12 HOLES H7

AΦ120

Øb

C

f Ag

A

Ød

DIMENSIONS TOLERANCESPART NO:

b c d e f G

1 15 7 8h8 47 0.005 0.005

2 20 8 10h8 58 0.01 0.008

3 30 10 15h9 70 0.02 0.01

4 50 12 25h9 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.

Facing to 55 mm length

Turning to Ø8 till 35mm 1010

Operation

Turning to Ø20 whole length 1005

1000

Oper. No. Sketch

PROCESS PLANNING

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

35±0.1 and 20±0.05

So 55 will be 55±0.15

T total = Some of individual Tolerances35±0.1 Tolerance = 0.220±0.05 Tolerance = 0.155±0.15 Tolerance = 0.3So T 55 = T 35 + T 20

i.e 0.3 = 02 + 0.1

Examples

Tolerance analysis

C

A B

C

A B

c1c2

b1b2

a1a2

C+c2 = ( A+a2 ) + (B+b2)So c2 = a2 + b2

Rule :- C = (A+B)

Tolerance analysisTolerance analysis

C2C1

( a2 + b2 )( a1 + b1 )

8 and 3

So 11 = 11

Now Tol8 = 0.1

Tol3 = 0.2 , Tol11 = 0.3

∴ Tol11 = Tol8 + Tol3

+0.2+0.1

-0.1-0.3

( +0.2 ) + ( -0.1 )( +0.1) + ( -0.3 )

+0.1- 0.2

Example

12 + 4 ±0.1 + 3

∴ 19 = 19

-0.2+0.1

-0.05-0.1

( +0.1) + (+0.1) +( -0.2 ) + (- 0.1) +

(+0.1)(+ 0.05)

+0.3-0.35

Tol 12 = 0.3 , Tol 4 = 0.2

Tol 3 = 0.15 , Tol 19 = 0.65

B

A

C B

A

C

a2a1

b2b1

c1c2

( a2 – b1 )( a1 – b2 )C = A - B

a2 a1

b2b1

12 - 8 ±0.1 = 4

i.e. 4∴ Tol 12 = 0.2

Tol 8 = 0.2Tol 4 = 0.4

- 0.1- 0.3

0.00- 0.40

(- 0.1) – (- 0.1 )(- 0.3) – (+0.1)

12 + 4 ±0.1 + 3 - 5 ±0.1 + 4

∴ 18 = 18

+ 0.2+ 0.1

- 0.05+ 0.1

+ 0.2+ 0.1

+ 0.2 + 0.1 + 0.1 + 0.1 + 0.2+ 0.1 – 0.1 – 0.05 – 0.1 + 0.1

+ 0.70- 0.05

T12 + T4 + T3 + T4 – T5 = T18

EXAMPLE1

2

0.1 + 0.2 + 0.15 + 0.1 – 0.2 = 0.75i.e.

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 changeTheory 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 values of 22 and 4

i.e to get 18±0.05 change the change the Tolerance of 22 and 4

X2X1

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

60

B40

± 0.05

ØA

H8

Ø14

H8(

25µ)

P- 0.1

A

E± 0.1

Ø0.1

Ø20

c H8

D- 0.5

(Ø6H8)⊥ A

E F± 0.02± 0.02

F

LOCATION

CAN WE CHANGE DATUM ?

(80

112± 0.05

± 0.1)

2012

X1 X2

- 0.05

80 ± 0.1

0.5 A B C 0.5 A B C

15 15

8x 8x

105 105

R R

SR SR

SØ SØ

CR NONE

NONE

ST NONE

or or

**

May be filled or not filled

Limits Fits Tolerances

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