Influence of structure errors in five-axis machining centers on the machining accuracy

The most fundamental cause of machining error is kinematic error due to the structure errors in machine tools. In this paper, thirteen structure errors are defined for three typical types of five-axis machining centers, which are the tool-tilting type, the work-tilting type, and the tool-work-tilting type. The structure errors are further categorized into alignment errors and adjustment errors. The number of alignment errors, which are essential static errors between adjacent elements in the machine tool and can be only corrected by reassembling the structure, is dependent on the type of machining center. The influence of structure errors on the machining accuracy is evaluated through the computer simulation by applying the National Aerospace Standard. When the machine tool of tool-tilting type is used for machining, the structure errors mostly affect the shape of the machined part. On the other hand, the structure errors in the work-tilting type mostly cause dimensional errors of the machined part.