Page 224 - CITS - ED - Mechanical

ENGINEERING DRAWING - CITS

Fig 19 Fig 20

Important notes
The specification of surface roughness is unnecessary whenever the ordinary manufacturing processes by them-
selves ensure an acceptable surface finish.

Illustrative examples
Examples incorporating the surface roughness values, production method, sampling length, direction of lay and
machining allowance are given below as illustration. The values quoted are purely typical and illustrative.
Symbols with inscription
TABLE 4

Symbol Meaning

Basic symbol may only be used alone when it
meaning is explained by a note.

A machined surface with no indication of
any detail.

A surface from which the removal of material
is prohibited. This symbol may also be used
in the drawing relating to production process
to indicate that a surface is to be left in the state
resulting from a preceeding manufactu-ring pro-
cess, whether this state was achieved by removal
of material or otherwise.

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CITS :Engineering Drawing (Mechanical) - Exercise 9 CITS :Engineering Drawing (Mechanical) - Exercise 9