2. Causes of Workpiece Variation
• The machines which perform operations on the
workpiece may have inherent inaccuracies built into
them.
• The tools used on the machines are subject to
dulling, general wear, chipping, breaking, and
differences occurs due to regrinding
• The material used is subjected to variations
• The involvement of human elements
• Any other cause by Chance.
3. Term used in dimensioning workpiece
dimensions
•Nominal Size: It has no specified limits or accuracy but
indicates a close approximation to some
standard size. For eg. a half inch nut will
fit into a half inch bolt.
Basic Size: It is the exact theoretical size from which the
limits are established through the
applications of allowances and tolerances.
Allowance: an allowance is an intentional difference
between maximum material limits of
mating parts.
Tolerance: A tolerance is the total permissible variation
from the specified basic size of the part.
Limit: Limits are extreme permissible dimension of the part
8. Mass property calculations
The correctness of the calculations will depend completely on the knowledge
used in choosing the axis.
Hypothetically, these axes can be at any position relative to the object being
considered, offered the axes are equally perpendicular.
But, in reality, except the axes are chosen to be at a position that can be
precisely measured and identified, the calculations are meaningless.
9. Calculating Center of gravity
location
Described the ‘center of mass’of the object.
The location where the object would balance
The single point where the static balance moments are all zero about three
mutually perpendicular axis.
The centroid of object the volume when the object is homogeneous.
The point where the total mass of the component could be measured to be
concentrated while static calculations.
The point about where the component rotates in free space
