Page 227 - CITS - ED - Mechanical

ENGINEERING DRAWING - CITS

System of limits and fits are followed by countries based on the ISO (International Standard Organisation) spec-
ifications.
System of limits and fits followed in our country is that stipulated by the BIS (Bureau of Indian Standard)
Other systems of limits and fits
– British Standard System (BSS)

– German Standard (DIN)
The Indian standard system of limits
and fits - Terminology

Size
It is a number expressed in a particular unit in the measurement of length.
Basic size: It is the size based on which the dimensional deviations are given. (Fig 1)

Actual size: It is the size of the component by actual measurement after it is manufactured. It should lie between
the two limits of size if the component is to be accepted.
Limits of size: These are the extreme permissible sizes within which the operator is expected to make the com-
ponent. (Maximum and minimum limits) (Fig 2)

Fig 1 Fig 2

Maximum limit of size: It is the greater of the two limits of sizes. (Fig 2) & (Table 1)
Minimum limit of size: It is the smaller of the two limits of sizes. (Fig 2) & (Table 1)

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CITS :Engineering Drawing (Mechanical) - Exercise 9