Shot Peening Statistics

Author:  Dr. David Kirk | Coventry University
Source:  The Shot Peener magazine, Vol 37, Issue 3, Summer 2023
Doc ID:  2023026
Year of Publication:  2023
Abstract:  
INTRODUCTION The purpose of this article is to assist readers in understanding the increasing number of applications of statistics in shot peening. Mathematics here is kept as simple as possible. The worst abuse of statistics occurs when measurements are simply entered into a formula which is not appropriate. Statistical programs are now routinely available, e.g., within Excel. Many shot peening factors vary including shot particle diameter, air pressure, wheel speed and Almen gauge parameters. Best practice demands that measurement values, i.e., data, are carefully stored and accessible. Every piece of data can be regarded as being a result from an experiment and has lasting value. It is regrettable that some companies discard data after it has served its immediate purpose. Statistics is the science of making decisions in the face of uncertainty. We cannot know, for example, what exactly the arc height of an individual peened Almen strip will turn out to be. This is in spite of our best efforts. Random variation of measurement factors will always occur and there may also be systematic variation—as, for example, when supplied air pressure falls steadily.