Question

Which of the following is true for a mean and center line of profile?

(a) When the waveform is repetitive then there is some difference between mean and centre line

(b) Mean line of profile is the mean distance between more prominent irregularities

(c) Mean line profile is the average value of ordinates from mean line

(d) Centre line of profile is the line which is parallel to the direction of profile and area embraced above and below the line is equal

This question was addressed to me by my college professor while I was bunking the class.

This interesting question is from Terminology as per Indian Standards topic in chapter Measurement of Surface Finish of Engineering Metrology

Answer 1

The correct option is (d) Centre line of profile is the line which is parallel to the direction of profile and area embraced above and below the line is equal

For explanation: Mean line of the profile is the line which have the form of the geometrical profile. Mean line of profile divides the effective profile so that the sum of the squares of distances between effective points and the mean line is a least. When the waveform is repetitive, the centre and mean line are equivalent.