A general model to estimate hole location deviation in drilling: the contribution of three error sources

Geometric accuracy is a critical performance factor for machining, especially when one of the basic requirements is high precision. In this paper, a general and systematic approach is shown to model hole geometric deviation from nominal due to the geometric errors of three important elements of the drilling process: the locators, the workpiece datum surface and the machine tool. The proposed approach was used for calculating the deviation from nominal of lots of drilled holes on a plate in order to evaluate the influence of the locator errors, of the form deviation of the part datum surfaces and of the volumetric error of the machine tool. Those parameters’ influence was evaluated through a design of experiments technique with a factorial plane implemented in a Matlab® file, allowing a saving of time, energy and material. It was found that the volumetric error of the machine tool influenced mainly the drilled hole location deviation from nominal.