What is Shot Peening?

A. Hi.

In a way, shot peening is similar to bead blasting -- the surface is repeatedly impacted with thousands of tiny, hard, balls -- but the purpose, and therefore the operating parameters, are different.

The purpose is to indent and compress the surface, and a couple of common reasons for that would be to make it more compatible with the stresses of subsequent plating, and to make the component less sensitive to fatigue failure.

What happens with "fatigue" loading is that the stresses on the component vary, sometimes even all the way from tensile to compressive and back. This repetitive sequence, if the loading stresses are rather severe, can cause a high stress point on the surface to fail, or a very tiny existing crack, a stress riser, to get worse with every cycle until failure.

What shot peening does in this case is put a permanent compressive stress into the surface, such that even under tensile load the surface of the component never goes tensile, or at the least, stays only very mildly tensile, so that fatigue failure is not initiated. One of the best known examples of shot peened components are the landing gear on airliners.

You can search the site with additional search terms of your choice to see several dozen threads about specific aspects of shot peening.

Luck & Regards,


Ted Mooney, P.E. RET
Striving to live Aloha
finishing.com - Pine Beach, New Jersey
(Ted is also available for instant or long
term paid consultation and assistance)