Limits Fits Tolerances

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Fundamentals of

LIMITS, FITS and TOLERANCES

Ability needed to

REPRESENT

INTERPRET

MANUFACTURE

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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 Ø 38. 0 0-0.2 Ø29. 2 +0. 016 35,95± 0.125 59,45± 0.125 A 0.025 M 0.025 A 0.025 M 0.025 M 0.015 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 C1.15 B DETAIL AT B 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

CAD REF . : DN NGT_GSL_RD040669-04 PN : TRANSMISSION TOOLS

DO NOT SCALE : IF IN DOUBT. REFER DESIGN OFFICE

APPD. DGNR BY SIGNDATE SIZE - C TO BE USED ON TOOL NO : XXXX/Y SHEET 1 OF 1 SCALE 1 :1 TOOL NAME: BLANK DRAWING(TURNED) PART NAME: FIFTH GEAR - LAYSHAFT

UNSPECIFIED MACHINING DEVIATION

MATERIAL AS NOTED

LINEAR DIMENSION ANGULAR DIMN. Above UptoDevn.

0.56 306 ±0.1±0.2 30 120±0.3 ±0.5 315 120 3151000±0.8 ±1.2 2000 1000 Short side of angle ± mmDeg. of min 1 Above Upto10 50 120 12050 10 0.11030 20 10 0.8 0.5 0.2

FOR ENGG. REF.

AT ALLOWANCE 0.15 ± 0.075 0.15 ± 0.075 0.2 BORE FRONT FACE BOSS FACE

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Different types of tolerances are

1. Dimensional Tolerances

2. Form Tolerances

3. Position Tolerances

4. Surface Roughness values

5. 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:

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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

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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 coarse c ± 2 ± 1,2 ± 0,8 ± 0,5 ± 0,3 ± 0,2 ± 0,1 ± 0,1 medium m -± 0,5 ± 0,3 ± 0,2 ± 0,15 ± 0,1 ± 0,05 ± 0,05 fine f Over 2000 up to 4000 Over 1000 up to 2000 Over 400 up to 400 Over 120 up to 120 Over 30 up to 120 Over 6 up to 30 Over 3 up to 6 0.5 up to 3 Descripti on Desig nation

Permissible deviations for basic size range Tolerance 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 ± 0,4 ± 0,1 ± 2 coarse c medium m ± 0,2 ± 0,5 ± 1 fine f over 6 Over 3 up to6 0.5 up to 3 Descriptio n Designation

Permissible deviations for basic size range

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Table 3 – Permissible deviations of angular dimensions ± 00 ₂₀ ± 00_30’ ± 10 ± 20 ± 30 very coarse v ± 00₁₀ ± 00 _15’ ± 00_30’ ± 10 ± 10 ₃₀’ coarse c medium m ± 00 ₅ ± 00 _10’ ± 00 _20’ ± 00 ₃₀ ± 10 fine F over 400 over 120 up to 400 over 50 up to 120 over 10 up to 50 up to 10 Descript ion Desig nation

Permissible deviations for ranges of lengths, in millimeters,

of the shorter side of the angle concerned Tolerance Class

Table 1 – General tolerances on straightness and flatness

Values in millimeters

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

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Table-2 General tolerances on perpendicularity

Perpendicularity tolerances for ranges of nominal lengths of the shorter side

up to 100 _{up to 300}over 100 _{up to 1000}over 300 _{up to 3000}over 1000

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

Symmetry tolerances for ranges of nominal lengths up to 100 over 100 up to 300 over 300 up to 1000 over 1000 up to 3000 H 0,5 K 0,6 0,8 1 L 0,6 1 1,5 2

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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.

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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 –

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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.

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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

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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

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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

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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

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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

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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.

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}

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mm _{IT12 IT13 IT14}3)_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

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 6

TH

_{GRADE GETS 100%}

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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

(19)

(20)

Schematic

representation of the positions of

(21)

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,

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(23)

(24)

(25)

STRAIGHTNESS

ZONE OF TOLERANCE :- CYLINDER

(26)

:-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 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

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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

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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)

Figure18 Figure17

(29)

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).

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)

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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

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.

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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 A A COMMON ZONE 3XA

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).

(32)

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).

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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).

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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 46

Figure 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).

(35)

• 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.

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FLATNESS

ZONE OF TOLERANCE :- TWO PARALLEL PLANES

SYMBOL

:-CIRCULARITY

CIRCULARITY

ZONE OF TOLERANCE :- TWO COPLANAR

CONCENTRIC CIRCLES

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:-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.

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CYLINDRICITY

ZONE OF TOLERANCE :- TWO COAXIAL CYLINDERS

SYMBOL

:-PROFILE OF ANY LINE

PROFILE OF ANY LINE

ZONE OF TOLERANCE :- TWO PROFILE LINES

(39)

:-PROFILE OF ANY SURFACE

PROFILE OF ANY SURFACE

ZONE OF TOLERANCE :- TWO PROFILED PLANES

(40)

:-POSITION TOLERANCES

(41)

PARALLELISM

ZONE OF TOLERANCE :- CYLINDER

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)

(42)

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

Indication and Interpretation 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

(43)

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.

Indication and Interpretation

PERPENDICULARITY

ZONE OF TOLERANCE :- TWO PARALLEL PLANES

PERPENDICULAR TO DATUM SURFACE

(44)

:-PERPENDICULARITY TOLERANCE

PERPENDICULARITY 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

(45)

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).

(46)

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.

ANGULARITY

ZONE OF TOLERANCE :-

TWO PARALLEL PLANES

INCLINED 60 DEGREE TO DATUM SURFACE.

SYMBOL

(47)

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).

(48)

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.

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)

(49)

The tolerance zone is limited by two parallel planes a distance t apart 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).

DEFINITION OF THE TOLERANCE ZONE INDICATION AND INTERPRETATION

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).

(50)

POSITION

ZONE OF TOLERANCE :- CYLINDER

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.

DEFINITION OF THE TOLERANCE ZONE INDICATION AND INTERPRETATION

(51)

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).

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.

(52)

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.

(53)

Position tolerance of a flat surface or a median

plane

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)

COAXIALITY

ZONE OF TOLERANCE :- CYLINDER

(54)

:-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.

(55)

SYMMETRY

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.

(56)

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.

(57)

CIRCULAR RUNOUT

ZONE OF TOLERANCE :- TWO COPLANAR

CONCENTRIC CIRCLES

(58)

:-TOTAL RUNOUT

TOTAL 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.

(59)

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

(60)

M12 0-0.2 Ø1 2 − Ø0.4 M Ø12.4 Ø0.4 Ø12 Ø12 Ø12

Actual Local Sizes

Tolerance zone Virtual size Tolerance zone

Ø0.6 Ø11.8 Ø1 2. 4 Virtual size Ø11.8 Ø11.8

Actual Local Sizes

D D Ø20 0 -0.1 D ⊥ Ø0.2 M M ØG Virtual Condition normal to Datum Plane D

Datum Plane D Øt A 1 _A2 A 3

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

(61)

Ø19.9 Ø19.9

Ø19.9

Actual Local Sizes Datum Plane D

Ø0

.3

Ø0

.2

Actual Local Sizes Datum Plane D ØG=Ø20.2 Ø20 Ø20 Ø20 ØG=Ø20.2

Dimensioning of profiles

(62)

70° FOLLWER 25 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° 12_0° 120° 12_0° 120° 120°

a) Indication on the drawing

_{b) Interpretation}

R8

0.1

Ø80

(63)

28 7 8 19 .5 17 10 13 14 14 7 14 21 21 10 8 7 0.1 A-B 35 14 14 7 Ø0.1 21 17 13 19 .5 28 14 21 35

A) Indication on the drawing B) Interpretation

270 R5 230 500 SR₈₀ SR80 R5 180 0.1

(64)

R5 270 SR8 0 R5 500 230 SR80 18 0

B) Interpretation

Ø44H 7 0.01/5 NOT CONVEX 0.03

Packing ring of a pump

Ø

22 H

(65)

Ø36 H8 A 0.01 A 0.01 A 0.02 A 0.04 A

Friction wheel

0.1 B A 20+0,18-0 8. 2H1 1 Ø 0.05 A A 0.01 A 0.01 A

Arbor for milling cutter

B 15

(66)

39 0.008 0.005 A Ø8 0 0.01 AB FIG. 5 Ø1 1H 7 B 0.02 AB Ø1 1H 7 A 0.01 B 0.025 A 0.008 B 0.005

Ball bearing inner ring

Roller

30 X 0.1 A 0.03 A 0.03 A SECTION XX 2525 25 A ( ) 0.02 A Ø47M 6 58 57 35 34

Bearing housing

(67)

Ø6H7 Ø18 _{0.02 A} A 0.03 A 5E9 CAM 9,015 9 R25.75 C A B 0.01 0.02 AB R16 0.02 C CL OF CAM LOBE R15.75 R4 R4 0.02 0.02 AB 0.08 AB 11°30"

Cam shaft

(68)

10 m_in 19 SECTION XX 11 0.05 A Ø1 08 8 HOLES EQUISPACED Ø11 0.01 A B 0.02 A B +0.06 -0 0.2 A B 8 HOLES EQUISPACED M8 40±0.1 70 160 25,5 Ø9 30° l 0.02 +0. 02 0 10 3x45°±2° 0 -0.0 5 B A Ø142 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 A Φ120

(69)

Øb C f A g A Ød

DIM ENSIONS TOLERANCES PART NO: 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

(70)

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

(71)

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 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

Examples

(72)

Tolerance analysis

C A B C A B c1 c2 b1 b2 a1 a2

C+c2 = ( A+a2

) + (B+b2)

So c

2

= a

2

+ b

2

Rule :- C = (A+B)

Tolerance analysis

C2 C1 ( 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

(73)

B A C B A C a2 a1 b2 b1 c1 c2 ( a2 – b1 ) ( a1 – b2 )

C = A - B

a2 a1 b2 b1 12 - 8 ±0.1 _{= 4} i.e. 4 ∴ Tol 12 = 0.2 Tol 8 = 0.2 Tol 4 = 0.4 - 0.1 - 0.3 - 0.400.00 (- 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

T

12

+ T

4

+ T

3

+ T

4

– T

5

= T

18

EXAMPLE

1

2

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

Series dimensioning not preferred

Parallel dimensions are most preferred , since

Tolerance get added in series dimensioning

(74)

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

values of 22 and 4

i.e to get 18

±0.05

_{change the change the Tolerance of 22 and 4}

X2 X1

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

(75)

60 B 40 ± 0.05 ØA H8 Ø14 H8( 25 µ ) P - 0.1 A E± 0.1 Ø0.1 Ø20 c H8 D - 0.5 (Ø6H8) ⊥ A E± 0.02 F± 0.02 F LOCATION

(76)

(80 112± 0.05 ± 0.1 ) 20 12 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 * *

(77)