eml 2023 – clearance fits lecture 2 – clearance fits

34
EML 2023 – Clearance Fits Lecture 2 – Clearance Fits

Upload: ashleigh-sleep

Post on 14-Dec-2015

259 views

Category:

Documents


3 download

TRANSCRIPT

Page 1: EML 2023 – Clearance Fits Lecture 2 – Clearance Fits

EML 2023 – Clearance Fits

Lecture 2 – Clearance Fits

Page 2: EML 2023 – Clearance Fits Lecture 2 – Clearance Fits

EML 2023Computer Aided Design

Cylindrical Fits

2

Page 3: EML 2023 – Clearance Fits Lecture 2 – Clearance Fits

EML 2023Computer Aided Design

Cylindrical Fits – English Units

3

Page 4: EML 2023 – Clearance Fits Lecture 2 – Clearance Fits

EML 2023Computer Aided Design

Cylindrical Fits – English Units

4

Page 5: EML 2023 – Clearance Fits Lecture 2 – Clearance Fits

EML 2023Computer Aided Design

Cylindrical Fits – English Units

5

Page 6: EML 2023 – Clearance Fits Lecture 2 – Clearance Fits

EML 2023Computer Aided Design

Cylindrical Fits – English Units

6

Page 7: EML 2023 – Clearance Fits Lecture 2 – Clearance Fits

EML 2023Computer Aided Design

Cylindrical Fits – English Unitstolerance - difference between the

limits of size for a single feature ; shaft .0025 ; hole .0040

limits of tolerance – the max and min sizes of a single feature

allowance – the tightest fit between two mating parts ; .0050

nominal size – the general size of a shaft or hole ; 1.5

basic size – the size to which the plus-and minus is applied

actual size – the measured size of the finished part

fit - the degree of tightness or looseness between two assembled parts

7

Page 8: EML 2023 – Clearance Fits Lecture 2 – Clearance Fits

EML 2023Computer Aided Design

Cylindrical Fits – English Units

• clearance fit – gives a clearance between two assembled mated parts ;

• min clearance .005 ;

• max clearance .0115

• transition fit

• interference fit

• line fit

8

Page 9: EML 2023 – Clearance Fits Lecture 2 – Clearance Fits

EML 2023Computer Aided Design

Cylindrical Fits – English Units

• clearance fit

• interference fit – a binding fit that requires the parts to be forced together, much as if they were welded

• transition fit – may range from a interference fit to a clearance fit between the mated parts

• line fit – results in surface contact or clearance when limits are reached

9

Page 10: EML 2023 – Clearance Fits Lecture 2 – Clearance Fits

EML 2023Computer Aided Design

Cylindrical Fits – English Units

• The ANSI B4.1 standard defines a series of fits between cylindrical features in inches for the basic hole system.

• The types of fits covered in the standard are:– RC: running or sliding clearance fits– LC: clearance locational fits– LT: transition locational fits– LN: interference locational fits– FN: force and shrink fits

10

Page 11: EML 2023 – Clearance Fits Lecture 2 – Clearance Fits

EML 2023Computer Aided Design

Cylindrical Fits – English Units

• RC: running or sliding clearance fits– RC1 to RC9

• LC: clearance locational fits• LC1 to LC11

• LT: transition locational fits• LT1 to LT6

• LN: interference locational fits• LN1 to LN3

• FN: force and shrink fits• FN1 to FN5

11

Page 12: EML 2023 – Clearance Fits Lecture 2 – Clearance Fits

EML 2023Computer Aided Design

Example – RC9 Fit

• hole and shaft have a basic diameter of 2.5”• From Tables in Appendix 29

thousands of an inch

12

Page 13: EML 2023 – Clearance Fits Lecture 2 – Clearance Fits

EML 2023Computer Aided Design

Example – LT3 Fit

• hole and shaft have a basic diameter of 2.5”• From Tables in Appendix 31

thousands of an inch

2.50122.5000

2.50082.5001

13

Page 14: EML 2023 – Clearance Fits Lecture 2 – Clearance Fits

EML 2023Computer Aided Design

Example – LN2 Fit

• hole and shaft have a basic diameter of 2.5”• From Tables in Appendix 32

thousands of an inch

2.50122.5000

2.50212.5014

14

Page 15: EML 2023 – Clearance Fits Lecture 2 – Clearance Fits

Example Problem

15

Page 16: EML 2023 – Clearance Fits Lecture 2 – Clearance Fits

EML 2023Computer Aided Design

Cylindrical Fits – Metric Units

• ANSI B4.2 standard • basic size – the diameter from which limits are calculated

• upper and lower deviation – the difference between the hole or shaft size and the basic size

• tolerance - the difference between the maximum and minimum sizes

16

Page 17: EML 2023 – Clearance Fits Lecture 2 – Clearance Fits

EML 2023Computer Aided Design

Cylindrical Fits – Metric Units

17

Page 18: EML 2023 – Clearance Fits Lecture 2 – Clearance Fits

EML 2023Computer Aided Design

Cylindrical Fits – Metric Units

• fundamental deviation – a letter grade that describes the deviation closest to the basic size

• International Tolerance (IT) grade – a series of tolerances that vary with the basic size to provide a uniform level of accuracy within a given grade

• there are 18 IT grades: IT01, IT0, IT1, …, IT16

18

Page 19: EML 2023 – Clearance Fits Lecture 2 – Clearance Fits

EML 2023Computer Aided Design

Cylindrical Fits – Metric Units

• Hole basis– a system of fits based on the minimum hole size as the basic

diameter– the fundamental deviation for a hole-basis system is “H”– Appendices 35 and 36 give hole-basis data for tolerances

• Shaft basis – a system of fits based on the maximum shaft size as the basic

diameter– the fundamental deviation for a hole-basis system is “h”– Appendices 37 and 38 give shaft-basis data for tolerances

19

Page 20: EML 2023 – Clearance Fits Lecture 2 – Clearance Fits

20

Page 21: EML 2023 – Clearance Fits Lecture 2 – Clearance Fits

EML 2023Computer Aided Design

Cylindrical Fits – Metric Units

21

Page 22: EML 2023 – Clearance Fits Lecture 2 – Clearance Fits

EML 2023Computer Aided Design

Cylindrical Fits – Metric Units

22

Page 23: EML 2023 – Clearance Fits Lecture 2 – Clearance Fits

EML 2023Computer Aided Design

Example 1

• determine the shaft and hole limits for:– hole-basis system– a close running fit– a basic diameter of 49 mm– use a preferred size

23

Page 24: EML 2023 – Clearance Fits Lecture 2 – Clearance Fits

24

Page 25: EML 2023 – Clearance Fits Lecture 2 – Clearance Fits

EML 2023Computer Aided Design

Example 1

• use a preferred basic diameter of 50 mm

• use a fit of H8/f7

25

Page 26: EML 2023 – Clearance Fits Lecture 2 – Clearance Fits

EML 2023Computer Aided Design

Example 2

• determine the shaft and hole limits for:– hole-basis system– a location transition fit– a basic diameter of 57 mm– use a preferred size

26

Page 27: EML 2023 – Clearance Fits Lecture 2 – Clearance Fits

EML 2023Computer Aided Design

27

Page 28: EML 2023 – Clearance Fits Lecture 2 – Clearance Fits

EML 2023Computer Aided Design

Example 2

• use a preferred basic diameter of 60 mm

• use a fit of H7/k6

28

Page 29: EML 2023 – Clearance Fits Lecture 2 – Clearance Fits

EML 2023Computer Aided Design

Example 3

• determine the shaft and hole limits for:– hole-basis system– a medium drive fit– a basic diameter of 96 mm– use a preferred size

29

Page 30: EML 2023 – Clearance Fits Lecture 2 – Clearance Fits

30

Page 31: EML 2023 – Clearance Fits Lecture 2 – Clearance Fits

EML 2023Computer Aided Design

Example 3

• use a preferred basic diameter of 100 mm

• use a fit of H7/s6

31

Page 32: EML 2023 – Clearance Fits Lecture 2 – Clearance Fits

EML 2023Computer Aided Design

Nonstandard Fits, Nonpreferred Sizes

• determine the shaft and hole limits for:– hole-basis system– a close running fit– a basic diameter of 45 mm

(do not change to a preferred size)

32

Page 33: EML 2023 – Clearance Fits Lecture 2 – Clearance Fits

33

Page 34: EML 2023 – Clearance Fits Lecture 2 – Clearance Fits

EML 2023Computer Aided Design

Nonstandard Fits, Nonpreferred Sizes

• use a fit of H8/f7

34