Limits Fits

48
Fundamentals of LIMITS, FITS and TOLERANCES

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limits fits presentation.

Transcript of Limits Fits

  • Fundamentals of LIMITS, FITS and TOLERANCES

  • Tolerance: Tolerance is the total permissible variation from the specified basic size of the part. It is defined as the magnitude of permissible variation of a dimension or measured control criterion from specified value.Basic size: The basic size is the size on which variation permitted.

    Actual size: The size of a feature obtained by measurement

  • TOL not specifiedFollow general engineering toleranceIS 2102 fine, medium, course & very courseUnless otherwise specified, it is medium.Or else it can be IT 14 VALUE, bilateralAll drawings need contain conditions on general tolerance.

  • 1. Open tolerances or General Engineering tolerancesStandards used are IS 2102 ( Part 1) 1993 / ISO 2768 - 1 : 1989General TolerancesPart 1: Tolerances for Linear and Angular dimensions without individual tolerance indicationsPart 2: Geometrical Tolerances for features without individual tolerance indicationsEx: 20.0, 20-f, 20-f H

  • Table 1 Permissible deviations for linear dimensions except for broken edges(external radii and chamfer heights, see table 2)Values in millimeters

    Tolerance ClassPermissible deviations for basic size rangeDesignationDescription0.5up to3Over3up to6Over6up to30Over30up to120Over120up to120Over400up to400Over1000up to2000Over2000up to4000ffine 0,05 0,05 0,1 0,15 0,2 0,3 0,5-mmedium 0,1 0,1 0,2 0,3 0,5 0,8 1,2 2ccoarse 0,2 0,3 0,5 0,8 1,2 2 3 4vvery coarse- 0,5 1 1,5 2,5 4 6 81) For nominal sizes below 0,5 mm, the deviations shall be indicated adjacent to the relevant nominal size (s).

  • Table 2 Permissible deviations for broken edges ( external radii and chamfer heights) Values in millimeters

    Tolerance ClassPermissible deviations for basic size rangeDesignationDescription0.5 up to 3Over 3 up to6over 6ffine 0,2 0,5 1mmediumccoarse 0,4 0,1 2vvery coarse1) For nominal sizes below 0.5 mm, the deviations shall be indicated adjacent to the relevant nominal size(s).

  • Table 3 Permissible deviations of angular dimensions

    Tolerance ClassPermissible deviations for ranges of lengths, in millimeters,of the shorter side of the angle concernedDesignationDescriptionup to 10over 10 up to 50over 50 up to 120over 120 up to 400over 400Ffine 10 00 30 00 20 00 10 00 5mmediumccoarse 10 30 10 00 30 00 15 00 10vvery coarse 30 20 10 00 30 00 20

  • Table 1 General tolerances on straightness and flatness Values in millimeters

  • Table-2 General tolerances on perpendicularityValues in millimeters

  • Table-3 General tolerances on symmetry Values in millimeters

  • Table 4 General tolerances on circular run-outValues in mm

  • IS 2102 PART 2VALUES FOR Straightness / perpendicularity / symmetry / Run out specifiedCircularity - limited to diameter tolerance or run out valueCylindricity Limited to combined effect of CIRCULARITY& PARALLELISM.Parallelism Limited to Dimensional Tolerance & flatness tolerance.Coaxiality - Limited to run out tolerance.

  • ISO 2768 - mGeneral Engg. Tole Tolerance class medium

    IS 2102 fGeneral Engg. Tole class fine

  • ISO 2768 mK

    General Engg. Tole for dimensions - Tolerance class. mGeneral Engg. Tole for form / position tolerance class. K

  • ISO 2768 - KGeneral tol. as dim not considered. Form/position as per tol. Class K.

  • SPECIFIED TOLERANCEVALUE GIVENVALUE AND POSISTIONAL STATUS GIVENSTD.SYMBOLS USED.

  • 2. Specificied tolerancesStandards usedIS 919 (Part 1) 1993 / ISO 286 1 : 1988ISO System of Limits and Fits

    Part 1: Bases of tolerances, Deviations and FitsPart 2:Tables of standard tolerance Grades and limit Deviations for Holes and shaft.

    Example : 20H7, 20g6, 30 + 0.02

    Specific tolerance should be less than open tolerance

  • STANDARD SPECIFICATION Need contain

    HOW MUCH IS THE VALUE OF TOL.WHERE IT IS DISPOSED.

  • HOW MUCH IS THE VALUEIS 919 / SP46 OR STD CHARTS SPECIFY.18 GRADES ARE SPECIFIED. VALUE IS ATTACHED TO A GRADEIT=INTERNATIONALTOLERANCE GRADE.AND 18 REPRESENT THE ROUGHFEST Mfg processEVERY MANUFACTURING PROCESS IS ATTRIBUTED WITH A RANGE OF ACCURACY GRADE

  • HOW MUCH IS THE VALUE FOR EX;TURNING IT7, 8 OR 9 GRINDING IT 5, OR 7MILLING IT 6, 7, OR 8LAPPING IT 1, 2, 3, OR 4SAND CASTING IT 16, 17, 18PRESS WORKING IT 10, 11 OR 12INJ. MOULDINGIT 12. 123 OR 14

  • Grades of tolerances obtainable by various manufacturing processes

    According to IS 18 grades of tolerances or accuracy grades of manufacturing IT1, IT2, IT3.IT18

    IT GRADE is generally indicated by numbers from 1 to 18

  • HOW MUCH IS THE VALUE. EVERY DIM. ALONG WITH A GRADE RECEIVE A TOL. VALUE.FOR EX. DIM 40 & GRADE 8, TOL= ?STD. FORMULA APPLIES TO THIS VALUEFOR CONVENIENCE, DIMES. ARE GROUPED. 0 TO 3; 3 TO 6; 6 TO 10 etc.SAME VALUE OF TOL. VALID FOR A DIA GROUP WITH ONE GRADE.

  • Table 1 Numerical values of standard tolerance grades IT for basic sizes up to 3 150 mm

    Basic size

    mm

    Standard tolerance grades

    IT12)

    IT22)

    IT32)

    IT42)

    IT52)

    IT6

    IT7

    IT8

    IT9

    IT10

    IT11

    IT12

    IT13

    IT143)

    IT153)

    IT163)

    IT173)

    IT183)

    Above

    Up to

    and in- cluding

    Tolerances

    (m mm

    -

    33

    0,8

    1,2

    2

    3

    4

    6

    10

    14

    25

    40

    60

    0,1

    0,14

    0,25

    0,4

    0,6

    1

    1,4

    3

    6

    1

    1,5

    2,5

    4

    5

    8

    12

    18

    30

    48

    75

    0,12

    0,18

    0,3

    0,48

    0,75

    1,2

    1,8

    6

    10

    1

    1,5

    2,5

    4

    6

    9

    15

    22

    36

    58

    90

    0,15

    0,22

    0,36

    0,58

    0,9

    1,5

    2,2

    10

    18

    1,2

    2

    3

    5

    8

    11

    18

    27

    43

    70

    110

    0,18

    0,27

    0,43

    0,7

    1,1

    1,8

    2,7

    18

    30

    1,5

    2,5

    4

    6

    9

    13

    21

    33

    52

    84

    130

    0,21

    0,33

    0,52

    0,84

    1,3

    2,1

    3,3

    30

    50

    1,5

    2,5

    4

    7

    11

    16

    25

    39

    62

    100

    160

    0,25

    0,39

    0,62

    1

    1,6

    2,5

    3,9

    50

    80

    2

    3

    5

    8

    13

    19

    30

    46

    74

    120

    190

    0,3

    0,46

    0,74

    1,2

    1,9

    3

    4,6

    80

    120

    2,5

    4

    6

    10

    15

    22

    35

    54

    87

    140

    220

    0,35

    0,54

    0,87

    1,4

    2,2

    3,5

    5,4

    120

    180

    3,5

    5

    8

    12

    18

    25

    40

    63

    100

    160

    250

    0,4

    0,63

    1

    1,6

    2,5

    4

    6,3

    180

    250

    4,5

    7

    10

    14

    20

    29

    46

    72

    115

    185

    290

    0,46

    0,72

    1,15

    1,85

    2,9

    4,6

    7,2

    250

    315

    6

    8

    12

    16

    23

    32

    52

    81

    130

    210

    320

    0,52

    0,81

    1,3

    2,1

    3,2

    5,2

    8,1

    315

    400

    7

    9

    13

    18

    25

    36

    57

    89

    140

    230

    360

    0,57

    0,89

    1,4

    2,3

    3,6

    5,7

    8,9

    400

    500

    8

    10

    15

    20

    27

    40

    63

    97

    155

    250

    400

    0,63

    0,97

    1,55

    2,5

    4

    6,3

    9,7

    500

    6302

    9

    11

    16

    22

    32

    44

    70

    110

    175

    180

    440

    0,7

    1,1

    1,75

    2,8

    4,4

    7

    11

    630

    8002

    10

    13

    18

    25

    36

    50

    80

    125

    200

    320

    500

    0,8

    1,25

    2

    3,2

    5

    8

    12,5

    800

    10002

    11

    15

    21

    28

    40

    56

    90

    140

    230

    360

    560

    0,9

    1,4

    2,3

    3,6

    5,6

    9

    14

    1000

    12502

    13

    18

    24

    33

    47

    66

    105

    165

    260

    420

    660

    1,05

    1,65

    2,6

    4,2

    6,6

    10,5

    16,5

    1250

    16002

    15

    21

    29

    39

    55

    78

    125

    195

    310

    500

    780

    1,25

    1,95

    3,1

    5

    7,8

    12,5

    19,5

    1600

    20002

    18

    25

    35

    46

    65

    92

    150

    230

    370

    600

    920

    1,5

    2,3

    3,7

    6

    9,2

    15

    23

    2000

    25002

    22

    30

    41

    55

    78

    110

    175

    280

    440

    700

    1100

    1,75

    2,8

    4,4

    7

    11

    17,5

    28

    2500

    31502

    26

    36

    50

    68

    96

    135

    210

    330

    540

    860

    1350

    2,1

    3,3

    5,4

    8,6

    13,5

    21

    33

    1) Values for standard tolerance grades IT01 and IT0 for basic sizes less than or equal to 500 mm are given in ISO 286 1, annex A, table 5.

    2) Values for standard tolerance grades IT1 to IT5 (incl.) for basic sizes over 500 mm are included for experimental use.

    3) Standard tolerance grades IT14 to IT18 (incl.) shall not be used for basic sizes less than or equal to 1 mm.

  • Table 1 Numerical values of standard tolerance grades IT for basic sizes up to 3 150 mm

    Basic size

    mm

    Standard tolerance grades

    IT12)

    IT22)

    IT32)

    IT42)

    IT52)

    IT6

    IT7

    IT8

    IT9

    IT10

    IT11

    Above

    Up to

    and including

    Tolerances

    (m

    -

    33

    0,8

    1,2

    2

    3

    4

    6

    10

    14

    25

    40

    60

    3

    6

    1

    1,5

    2,5

    4

    5

    8

    12

    18

    30

    48

    75

    6

    10

    1

    1,5

    2,5

    4

    6

    9

    15

    22

    36

    58

    90

    10

    18

    1,2

    2

    3

    5

    8

    11

    18

    27

    43

    70

    110

    18

    30

    1,5

    2,5

    4

    6

    9

    13

    21

    33

    52

    84

    130

    30

    50

    1,5

    2,5

    4

    7

    11

    16

    25

    39

    62

    100

    160

    50

    80

    2

    3

    5

    8

    13

    19

    30

    46

    74

    120

    190

    80

    120

    2,5

    4

    6

    10

    15

    22

    35

    54

    87

    140

    220

    120

    180

    3,5

    5

    8

    12

    18

    25

    40

    63

    100

    160

    250

    180

    250

    4,5

    7

    10

    14

    20

    29

    46

    72

    115

    185

    290

    250

    315

    6

    8

    12

    16

    23

    32

    52

    81

    130

    210

    320

    315

    400

    7

    9

    13

    18

    25

    36

    57

    89

    140

    230

    360

    400

    500

    8

    10

    15

    20

    27

    40

    63

    97

    155

    250

    400

    500

    6302

    9

    11

    16

    22

    32

    44

    70

    110

    175

    180

    440

    630

    8002

    10

    13

    18

    25

    36

    50

    80

    125

    200

    320

    500

    800

    10002

    11

    15

    21

    28

    40

    56

    90

    140

    230

    360

    560

    1000

    12502

    13

    18

    24

    33

    47

    66

    105

    165

    260

    420

    660

    1250

    16002

    15

    21

    29

    39

    55

    78

    125

    195

    310

    500

    780

    1600

    20002

    18

    25

    35

    46

    65

    92

    150

    230

    370

    600

    920

    2000

    25002

    22

    30

    41

    55

    78

    110

    175

    280

    440

    700

    1100

    2500

    31502

    26

    36

    50

    68

    96

    135

    210

    330

    540

    860

    1350

    1) Values for standard tolerance grades IT01 and IT0 for basic sizes less than or equal to 500 mm are given in ISO 286 1, annex A, table 5.

    2) Values for standard tolerance grades IT1 to IT5 (incl.) for basic sizes over 500 mm are included for experimental use.

    3) Standard tolerance grades IT14 to IT18 (incl.) shall not be used for basic sizes less than or equal to 1 mm.

  • Table 1 Numerical values of standard tolerance grades IT for basic sizes up to 3 150 mm

    Basic size

    mm

    Standard tolerance grades

    IT12

    IT13

    IT143)

    IT153)

    IT163)

    IT173)

    IT183)

    Above

    Up to and

    including

    Tolerances

    mm

    -

    33

    0,1

    0,14

    0,25

    0,4

    0,6

    1

    1,4

    3

    6

    0,12

    0,18

    0,3

    0,48

    0,75

    1,2

    1,8

    6

    10

    0,15

    0,22

    0,36

    0,58

    0,9

    1,5

    2,2

    10

    18

    0,18

    0,27

    0,43

    0,7

    1,1

    1,8

    2,7

    18

    30

    0,21

    0,33

    0,52

    0,84

    1,3

    2,1

    3,3

    30

    50

    0,25

    0,39

    0,62

    1

    1,6

    2,5

    3,9

    50

    80

    0,3

    0,46

    0,74

    1,2

    1,9

    3

    4,6

    80

    120

    0,35

    0,54

    0,87

    1,4

    2,2

    3,5

    5,4

    120

    180

    0,4

    0,63

    1

    1,6

    2,5

    4

    6,3

    180

    250

    0,46

    0,72

    1,15

    1,85

    2,9

    4,6

    7,2

    250

    315

    0,52

    0,81

    1,3

    2,1

    3,2

    5,2

    8,1

    315

    400

    0,57

    0,89

    1,4

    2,3

    3,6

    5,7

    8,9

    400

    500

    0,63

    0,97

    1,55

    2,5

    4

    6,3

    9,7

    500

    6302

    0,7

    1,1

    1,75

    2,8

    4,4

    7

    11

    630

    8002

    0,8

    1,25

    2

    3,2

    5

    8

    12,5

    800

    10002

    0,9

    1,4

    2,3

    3,6

    5,6

    9

    14

    1000

    12502

    1,05

    1,65

    2,6

    4,2

    6,6

    10,5

    16,5

    1250

    16002

    1,25

    1,95

    3,1

    5

    7,8

    12,5

    19,5

    1600

    20002

    1,5

    2,3

    3,7

    6

    9,2

    15

    23

    2000

    25002

    1,75

    2,8

    4,4

    7

    11

    17,5

    28

    2500

    31502

    2,1

    3,3

    5,4

    8,6

    13,5

    21

    33

    1) Values for standard tolerance grades IT01 and IT0 for basic sizes less than or equal to 500 mm are given in ISO 286 1, annex A, table 5.

    2) Values for standard tolerance grades IT1 to IT5 (incl.) for basic sizes over 500 mm are included for experimental use.

    3) Standard tolerance grades IT14 to IT18 (incl.) shall not be used for basic sizes less than or equal to 1 mm.

  • HOW MUCH IS THE VALUE 60% INCREASE IN TOL. VALUE FOR EVERY GRADE UP FOR A DIA GROUPEVERY 6TH GRADE GETS 100% MORE TOL VALUE

  • WHERE TO DISPOSE TOLE.TOL. CAN BE DISPOSEDABOVE BASIC DIM.BELOW BASIC DIMDISTRIBUTED ON EITHER SIDE

  • WHERE TO POSITIONPOSITIONING IS REPRESENTED BY CAPITAL LETTERS FOR HOLES A,B,HBY SMALL LETTERS FOR SHAFTS a,b,hSTD DISTANCES ARE KEPT EACH LETTER & FOR EACH DIA GROUP FROM BASIC DIM.THE DISTANCE TO THE BASIC DIM WITH LEAST VALUE IS TERMED AS FUNDEMENTAL DEVIASION; FD IS FIXED FOR A DIA-DIM COMBINATION.

  • Schematic representation of the positions of fundamental deviations

  • FITSWhen two parts to be assembled, the relation resulting from the difference between the size before assembly is called a fit.A fit is represented by 30 H 7 / g6, 30 H 7 / p6, 40 H7/h6, 40 H7k6, 40 H7p6,

  • MMC, LMC & RFSMMC - Dimension corresponding to Maximum Metal Condition (biggest shaft size or smallest hole size)LMC - Dimension corresponding to Least Metal Condition(smallest shaft or biggest hole size)RFS - Regardless of feature size

  • Actual Dimension vary from MMC limit to LMC limitWorst assembly condition exist when mating parts at MMCFunctional assembly requirements can be related to actual dimension by symbol in the drawing M