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DIMENSIONAL TOLERANCES AND METHODS OF FITS

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Title: PowerPoint Author: Rein Last modified by: Created Date: 9/20/2001 10:57:17 AM Document presentation format: – PowerPoint PPT presentation

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Title: DIMENSIONAL TOLERANCES AND METHODS OF FITS


1
Lesson 10
  • ?? ??? ??????
  • DIMENSIONAL TOLERANCES AND METHODS OF FITS
  • Importance of dimensional tolerances
  • Definitions
  • Tolerancing method
  • Type of fits
  • Methods of fits
  • Fits and deviations

2
IMPORTANCE OF DIMENSIONAL TOLERANCES
  • The workman cannot be expected to produce the
    exact size of part as indicated by the dimensions
    on a drawing.
  • a certain amount of variation on each
    dimension must be tolerated.
  • Especially, the problem of
    interchangeable manufacture developed from the
    making of parts to a supposedly exact size to the
    holding of part sizes between two limits lying so
    closely together that any intermediate size would
    be acceptable.

3
DEFINITIONS
  • Basic size (?? ??) reference size
  • Limit of size
  • The maximum and minimum sizes permitted for a
    specific dimension.
  • Maximum limit of size (?? ?? ?? ??)
  • Minimum limit of size (?? ?? ?? ??)

4
DEFINITIONS
  • ?? ?? ?? A 50.025 mm, a 49.975 mm
  • ?? ?? ?? B 50.000 mm, b 49.950 mm

5
DEFINITIONS
  • Deviation (?? ??? ?? ???) limit of size - basic
    size  
  • Upper deviation
  • maximum limit of size - basic size
  • Lower deviation
  • minimum limit of size - basic size

6
DEFINITIONS
  • Zero line (???)
  • ?? ?? 50.000 mm

7
DEFINITIONS
  • Tolerances Total permissible variation in its
    size
  • maximum limit of size - minimum limit of size
  • Upper deviation - Lower deviation
  • Allowance The intentional difference in
    correlated dimensions of mating parts

8
TOLERANCING METHODS (?? ?? ??)
  • Limit dimensioning Only the maximum minimum
    dimensions are specified

9
TOLERANCING METHODS
  • Plus and minus tolerancing The dimension of the
    specified size is given first, followed by
    expression of tolerance.

10
TOLERANCING METHODS (?? ?? ??)
11
TOLERANCING METHODS (?? ?? ??)
12
TOLERANCING METHODS (?? ?? ??)
13
TOLERANCING METHODS (?? ?? ??)
14
TYPE OF FITS (?? ??? ??)
  • Clearance (??) Interference (??)
  • Clearance bore diameter gt shaft diameter
  • Interference bore diameter lt shaft diameter
  • Clearance fit (??? ?? ??)
  • Transition fit (?? ?? ??)
  • Interference fit (?? ?? ??)

15
TYPE OF FITS (?? ??? ??)
  • p. 280 ? 13-6

16
TYPE OF FITS (?? ??? ??)
17
TYPE OF FITS (?? ??? ??)
18
METHODS OF FITS (?? ?? ??)
  • Basic bore system (???? ?? ??)
  • Basic size use a minimum limit of size of the
    bore
  • H5 - H10

19
METHODS OF FITS (?? ?? ??)
  • ???? ?? ?? ??

20
METHODS OF FITS (?? ?? ??)
  • ???? ?? ?? ??

21
METHODS OF FITS (?? ?? ??)
  • Basic shaft system (? ?? ?? ??)
  • Basic size use a maximum limit of size of the
    shaft
  • h4 - h9

22
METHODS OF FITS (?? ?? ??)
  • ???? ? ?? ??

23
METHODS OF FITS (?? ?? ??)
  • ???? ? ?? ??

24
ISO TOLERANCE (IT ?? ??)
  • 0 mm - 3150 mm ? ?? ??? ??
  • 21???? ??? ??

25
ISO TOLERANCE (IT ?? ??)
26
ISO TOLERANCE (IT ?? ??)
  • IT ?? ?? ??? ?
  • 6? ?????
  • ?? Ø 35 Ø45 ?? 0.016 3050? ??
  • ?? Ø 200     ?? 0.029 180250? ??
  • ?? 6? ?? ????? ???? ??? ??.
  • ??? ???? ??

27
FIT AND DEVIATION
  • ??? ?? ?? ? ??

28
FIT AND DEVIATION
  • ???
  • ??  Ø (??) (???? ??) (??)
  • ? Ø12H7 ? ? ?? ??? 0.018, ???? ??? 0
  • ?  Ø (??) (???? ??) (??)
  • ? Ø100H7 ? ? ?? ??? 0, ???? ??? - 0.035
  • ?? ?? ??
  • ? H8/g7

29
FIT AND DEVIATION
  • ?? Ø30f8 ? ?? ? ?? ??? ? ???? ???? ????.
  • f? ? ?? ???? ??? ?? ?? ???
  •  ? 10-5 ? ? ?? ??? -20
  •  ? 10-3 ? IT ???? 33
  • ? ?? ??? - ???? ??? IT ????
  • (-20) - (???? ???) 33
  • ? ???? ??? -53
  • ?

30
FIT AND DEVIATION
31
FIT AND DEVIATION
  • ???? ?? ?? ??

32
FIT AND DEVIATION
  • ? ?? ?? ?? ??
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