Question

What is the importance of the valley in any irregular surface?

(a) Reduce metal to metal contact

(b) Retain film of lubricating oil

(c) Reduce stress concentration

(d) Improve surface texture

I have been asked this question in an interview for internship.

Question is from Meaning of Surface Texture topic in chapter Measurement of Surface Finish of Engineering Metrology

Answer 1

Right choice is (b) Retain film of lubricating oil

For explanation I would say: The hills in any irregular surface helps in reducing metal to metal contact and valleys are useful to retain the film of lubricating oil on the surface otherwise it will be difficult to maintain lubricating oil film on the surface.