Module
1
Fundamentals of
machine design
Version 2 ME, IIT Kharagpur

Lesson
3
Brief overview of design
and manufacturing

Version 2 ME, IIT Kharagpur

Instructional Objectives:

At the end of this lesson, the students should be able to understand:

of the terminologies is given below. For the convenience, shaft and hole are
chosen to be two mating components.
Version 2 ME, IIT Kharagpur

Allowance
It is the difference of dimension between two mating parts.

Upper deviation
It is the difference of dimension between the maximum possible size of the
component and its nominal size.
Basic size
Unilateral Bilateral
Fig. 1.3.2 Types of tolerance
Max.
Diameter
(upper limit)
Min. Diameter

HOLE
(lower limit)

Tolerance
SHAFT
Basic Size
Lower
Deviation
Upper
Deviation
ZERO LINE
Allowance
Fig. 1.3.1 Interrelationship between tolerances and limits
Version 2 ME, IIT Kharagpur