This document discusses different types of fits between mating parts in mechanical assemblies, including clearance fits, interference fits, and transition fits. For clearance fits, the hole is larger than the shaft to allow free movement. For interference fits, the hole is smaller than the shaft to create friction. Transition fits allow for either a clearance or interference when assembled. The document explains how to interpret fit tolerances written on drawings using International Tolerance grades and deviation tables.

1. 1. PART AND ASSEMBLY DRAWINGS
2. SURFACE CHARACTERISTICS
3. DIMENSIONAL TOLERANCES
4. FITS
5. GEOMETRIC TOLERANCES
6. DIMENSIONING
7. THREADED FASTENING
8. SHAFT AND PIPE JOINERS
9. BEARINGS
10. GEARS 1: DEFINITION
11. GEARS 2: HELICAL
12. GEARS 3: BEVEL
13. BELTS AND CHAINS
14. WELDED JOINTS AND RIVETS
4. FITS

2. FITS
Industrial Drawing
CC 2015 Ramón Rubio
What if we join two pieces together?
CLEARANCE FIT
HOLE > SHAFT
We will have three cases depending on the fit
INTERFERENCE FIT
HOLE < SHAFT
TRANSITION FIT
HOLE = SHAFT
Maximum clearance
Minimum clearance
Maximum interference
Minimum interference
Maximum clearance
Maximum interference

3. FITS
Industrial Drawing
CC 2015 Ramón Rubio
Clearance Fit
A fit between mating parts
having limits of size so
prescribed that a
clearance always results
in assembly.
Clearance

4. FITS
Industrial Drawing
CC 2015 Ramón Rubio
Clearance Fit
Maximumclearance
Minimumclearance

5. FITS
Industrial Drawing
CC 2015 Ramón Rubio
Clearance Fit
HOLE HOLE
shaft
shaft
Zero line

6. FITS
Industrial Drawing
CC 2015 Ramón Rubio
Clearance Fit
Zero line
The tolerance of the Clearance Fit is…

7. FITS
Industrial Drawing
CC 2015 Ramón Rubio
A fit between mating
parts having limits of size
so prescribed that an
interference always
results in assembly
Interference Fit
Interference

8. FITS
Industrial Drawing
CC 2015 Ramón Rubio
Interference Fit
Maximum
interference
Minimum
interference

9. FITS
Industrial Drawing
CC 2015 Ramón Rubio
Interference Fit
HOLE HOLE
shaft
shaft
Zero line

10. FITS
Industrial Drawing
CC 2015 Ramón Rubio
Interference Fit
Zero line
The tolerance of the Interference Fit is…

11. FITS
Industrial Drawing
CC 2015 Ramón Rubio
A fit between mating parts having limits of size so
prescribed as to partially or wholly overlap, so that either
a clearance or an interference may result in assembly.
Transition Fit
shaft shaft
shaftHOLE
Zero line

12. FITS
Industrial Drawing
CC 2015 Ramón Rubio
Transition Fit
The tolerance of the Transition Fit is…

13. FITS
Industrial Drawing
CC 2015 Ramón Rubio
Shaft system
CLEARANCE FIT INTERFERENCE FIT TRANSITION FIT

14. FITS
Industrial Drawing
CC 2015 Ramón Rubio
Hole system
CLEARANCE FIT INTERFERENCE FIT TRANSITION FIT

15. FITS
Industrial Drawing
CC 2015 Ramón Rubio

16. FITS
Industrial Drawing
CC 2015 Ramón Rubio
Remember the way the tolerance is
indicated in parts and fits

17. FITS
Industrial Drawing
CC 2015 Ramón Rubio
What is meant by 40P6/k5?

18. FITS
Industrial Drawing
CC 2015 Ramón Rubio
1. Draw the zero line and the fit sketch
What is meant by 40P6/k5?

19. FITS
Industrial Drawing
CC 2015 Ramón Rubio
2. Find both TOLERANCES (IT grade-basic size table)
1. Draw the zero line and the fit sketch
What is meant by 40P6/k5?

20. FITS
Industrial Drawing
CC 2015 Ramón Rubio
2. Find both TOLERANCES (IT grade-basic size table)
1. Draw the zero line and the fit sketch
IT6 16µ
ø40
IT5 11µ
ø40
What is meant by 40P6/k5?

21. FITS
Industrial Drawing
CC 2015 Ramón Rubio
2. Find both TOLERANCES (IT grade-basic size table)
1. Draw the zero line and the fit sketch
IT6 16µ
ø40
3. Evaluate deviations (fundamental deviation table)
IT5 11µ
ø40
What is meant by 40P6/k5?

22. FITS
Industrial Drawing
CC 2015 Ramón Rubio
2. Find both TOLERANCES (IT grade-basic size table)
1. Draw the zero line and the fit sketch
IT6 16µ
ø40
3. Evaluate deviations (fundamental deviation table)
P6 ES=-21µ | EI=-21-16=-37µ
ø40
IT5 11µ
ø40
k5 ei=2µ | es=2+11=13µ
ø40
What is meant by 40P6/k5?

23. FITS
Industrial Drawing
CC 2015 Ramón Rubio
2. Find both TOLERANCES (IT grade-basic size table)
1. Draw the zero line and the fit sketch
IT6 16µ
ø40
3. Evaluate deviations (fundamental deviation table)
P6 ES=-21µ | EI=-21-16=-37µ
ø40
4. Answer:
AM=es-EI=13+37=50µ
Am=ei-ES=2+21=23µ
IT5 11µ
ø40
k5 ei=2µ | es=2+11=13µ
ø40
What is meant by 40P6/k5?

24. FITS
Industrial Drawing
CC 2015 Ramón Rubio
The fits in the drawings

25. FITS
Industrial Drawing
CC 2015 Ramón Rubio
General tolerances notes
“All tolerances +- 1mm
Unless otherwise noted”

26. 1. PART AND ASSEMBLY DRAWINGS
2. SURFACE CHARACTERISTICS
3. DIMENSIONAL TOLERANCES
4. FITS
5. GEOMETRIC TOLERANCES
6. DIMENSIONING
7. THREADED FASTENING
8. SHAFT AND PIPE JOINERS
9. BEARINGS
10. GEARS 1: DEFINITION
11. GEARS 2: HELICAL
12. GEARS 3: BEVEL
13. BELTS AND CHAINS
14. WELDED JOINTS AND RIVETS
4. FITS