Prediction of machining accuracy degradation of machine tools

Machine tool has to maintain its accuracy for quality control of products. After a long period of cutting operations, obvious wear will occur on the contact surfaces of the slide and the guideway. Such a wear will degrade the accuracy of machine tool due to the increase of Abbé errors. This research proposes a mathematical model so that, at given cutting forces and parameters of the slide-guideway, it is able to calculate the geometric errors of the slide due to contact deformation caused by the wear of the guideway and then predict the positioning errors after a long-term operation. Cutting forces applied to the worktable will cause reaction forces on contact surfaces between the slide and the guideway. Such reaction forces can be solved by static equilibrium equations of deformed free-body diagram of the slide. The induced abrasive wear can then be estimated. A simulation study on a heavy duty machine tool with slide-guideway will show the magnitude of wear on the sliding surface and the consequently caused geometric errors of the moving axis. Experimental tests show that, if modifying the wear coefficient to a function of sliding distance, the analytical result is in good agreement with the experimental result.

► Wear of contact surface of slide-guideway degrade the accuracy of machine tool due to the increase of Abbé errors.
► Elastic deformation of contact surface of slide-guideway caused geometric errors of the slide when it moves along the guideway.
► The wear coefficient of slide-guideway is function of sliding distance.