Control Charts for Radial Error

Abstract

In applications such as the drilling of holes or placement of components at a targeted location, the quality characteristic of interest is the radial distance of the center from its desired location. Control charts for radial error are established for the case where the center displacement errors in two orthogonal directions are normally and independently distributed with the same variance about the true center location. It is shown that a second chart based on the ratio of individual observed values of radial error can be used to distinguish between a radial shift in the means of the error distributions and an increase in their variability.