Introduction:

Contain degree of surface finish is required for the proper functioning of the working surface.

Types of surface finish:

  Nominal surface

  Rough surface

  Wavy surface

Elements of surface texture:

  Surface roughness

  Profile

  Flaw, Law, Waviness

  Cut off length

Datum of surface finish measurement:

The M system (The mean line system)

The E system (The envelope system)

Numerical value for surface finish:

1.   Peak –to- valley height

2.   The depth of smoothness

3.   The mean depth

4.   Centre line average

5.   Room mean square.

6.

Methods of measuring surface finish:

  Visual inspection

  Touch method

  Scratch method

Comparative or qualitative methods of surface finish measurement:

Direct methods:

  Stylus probe instrument

  Tomlinson surface meter

  Taylor Hobson”Talysurf”

  Profilometer