Methods to evaluate surface finish - Metrology & Quality Control

Q.  Which of the following methods is unreliable to evaluate the surface finish?
- Published on 07 Aug 15

a. Electrical stylus profilometer
b. Wallace surface dynamometer
c. Profilograph
d. Tomlinson surface tester

ANSWER: Wallace surface dynamometer


  • Sravanthi   -Posted on 26 Oct 15
    - Different methods are used to check surface finish. These are as follows:

    1) Inspection by comparison method
    2) Direct instrument measurement

    1) Inspection by comparison method

    - In this method, surface finish is assessed by observation or touching the surface.

    -Wallace surface dynamometer method largely depends upon scratch pattern and depends less on depth of the material. This method produces wrong results when compared with different surfaces produced by this method.

    Different types of comparison methods are:

    a) Wallace surface dynamometer
    b) Touch inspection
    c) Scratch inspection
    d) Visual inspection

    2) Direct instrument measurement

    - Electrical stylus profilometer, profilograph, Tomlinson surface tester are the methods used to measure roughness of a surface directly.

    - In electrical stylus method, up down motion of stylus on the surface generates electrical signals and is used to measure the roughness value.

    - Profilometers give quantitative evaluation of surface roughness.

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