The average height from a mean line of all ordinates of the surface, regardless of sign, is the _______.

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JKSSB JE Mechanical 02 Nov 2021 Shift 1 Official Paper

Answer 1

Explanation:

Whatever may be the manufacturing process, an absolutely smooth and flat surface cannot be obtained.
The machine element or parts retain the surface irregularities left after manufacturing.
The surface irregularities are usually understood in terms of surface finish, surface roughness, surface texture or surface quality.

Evaluation of surface roughness:

Centre Line Average Value

It is defined as the average height from a mean line of all ordinates of the surface, regardless of sign.

F1 S.S M.P 19.08.19 D8

\(Ra = \frac{{{A_1} + {A_2} + \ldots + {A_n}}}{L}\)