2-Fits and Tolerance
Module: Machine Element Design & Drawing DES 263
Associate Professors: Mohammed Ali Abdelnaby
Spring 2024
Presentation Topic
• Type of Fits
- Clearance Fit
- Transition Fit
- Interference Fit
• Hole and Shaft Basis
• Tolerance Zone
• Writing Tolerance
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Fundamental Tolerance Calculations
Fundamental Deviations Calculations
Standard Tables
Alternative Types of Fits
Examples
Recap
Geometrical Tolerance
Fits and Tolerance
Types of Fit
• The relation between two mating parts is known as a fit.
Depending upon the actual limits of the hole or shaft
sizes, fits may be classified as clearance fit, transition fit
and interference fit.
Clearance Fit
Clearance Fit
Interference Fit
Interference Fit
Transition Fit
Transition Fit
Hole and Shaft Basis
In working out limit dimensions for the three classes of fits; two
systems are in use, the hole basis system and the shaft basis system.
The hole basis system is preferred in most cases, since standard tools
like drills, reamers, broaches, etc., are used for making a hole, or if
the hole is a standard part.
The Shaft basis system is preferred if the shaft is a standard part.
Standard part: Bearing
Tolerance Zones
As it seen from the above figures; from ‘A’ to ‘H’ Clearance Fit,
‘J’ to ‘N’ Transition Fit, and from ‘P’ to ‘Z’ Interference Fit.
The letters I, L, O, Q, and W have not been used.
Tolerance Zones
• How to write it on drawings
W.D: Working drawing
C.D: Construction Drawing
• Alternative Types of fits
• Alternative Types of fits
• Fits Examples
Fits Examples
Clearance Fit
Transition Fit
Interference Fit
Example: 1
Example: 2
• ISO Fits and Tolerances according to DIN ISO 286 | Trelleborg
Recap (Clearance Fit)
Recap (Clearance Fit)
Recap (Clearance Fit)
Recap (Transition Fit)
Recap (Transition Fit)
Recap (Transition Fit)
Recap (Interference Fit)
Recap (Interference Fit)
Recap (Interference Fit)
Geometrical Tolerance
Faculty of
Engineering