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1 DIMENSIONING AND TOLERANCING. 2 prismatic.sldasm.

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Presentation on theme: "1 DIMENSIONING AND TOLERANCING. 2 prismatic.sldasm."— Presentation transcript:

1 1 DIMENSIONING AND TOLERANCING

2 2 prismatic.sldasm

3 3 DIFFERENT TYPES OF FIT Clearance fit Limits of size defined such that a clearance always results when mating parts are assembled Interference fit Limits of size are so prescribed that interference always results when mating parts are assembled. Transition fit Limits of size are so prescribed that either clearance or an interference may results when mating parts are assembled Line fit Limits of size are so prescribed that surface contact or clearance may result when mating parts are assembled

4 4 BASIC HOLE SYSTEM In the basic hole system the minimum (lower limit) hole size is taken as the basic size. Stock hole is made first and then shaft is made to particular type of fit (to suit the hole).

5 5 BASIC SHAFT SYSTEM In the basic shaft system the maximum (upper limit) shaft size is taken as the basic size. Stock shaft is created first and hole is made to particular type of fit (to suit the shaft).

6 6 Basic shaft or basic hole? In the basic hole system the minimum (lower limit) hole size is taken as the basic size. Stock hole is made first and then shaft is made to particular type of fit (to suit the hole). In the basic shaft system the maximum (upper limit) shaft size is taken as the basic size. Stock shaft is created first and hole is made to particular type of fit (to suit the shaft). IDENTIFY FIT SYSTEM

7 7 Shaft Hole - - = = What type of fit is this? IDENTIFY FIT SYSTEM

8 8

9 9 Basic hole More commonly used Basic shaft Less commonly used

10 10 Shown are limit tolerances IDENTIFY FIT SYSTEM

11 11 Surface roughness for different manufacturing methods

12 12

13 13 Φ Basic hole fits

14 14 Φ Basic shaft fits

15 15 Description of preferred fits

16 16 ANSI PREFERRED HOLE BASIS METRIC CLEARANCE FITS Pages 312, 313, 314, 315 ANSI PREFERRED SHAFT BASIS METRIC CLEARANCE FITS Pages 316, 317, 318, 319 Engineering Design Graphics James Leake Jacob Borgerson

17 17 cylindrical_metric.sldasm Nominal diameter 25mm Btw. what is wrong with this assembly?

18 18 Loose running fit for nominal diameter 25mm preferred hole basic

19 19 Free running fit for nominal diameter 25mm preferred hole basic

20 20 Close running fit for nominal diameter 25mm preferred hole basic

21 21 Sliding fit for nominal diameter 25mm preferred hole basic

22 22 Locational transition fit for nominal diameter 25mm preferred hole basic

23 23 Locational transition fit for nominal diameter 25mm preferred hole basic

24 24 Locational interference fit for nominal diameter 25mm preferred hole basic

25 25 Medium drive fit for nominal diameter 25mm preferred hole basic

26 26 Force fit for nominal diameter 25mm preferred hole basic

27 27 Hole is always the same: H7 We obtained the desired fit by changing shaft tolerance


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