Burr Minimisation in Face Milling with Optimised Tool Path

Abstract

In current manufacturing the burr-free edges of the workpieces are required after machining. Subsequently removing the burrs from the edges of the workpieces increases the cost and time of production. This is the reason why manufacturers try to avoid and reduce the burr.In face milling a possible solution to reduce the burr is the controlling of the exit angle. The exact value of the exit angle can be determined only numerically, however, if the path of the tool edge is approximated with a circle, then the approximation error can be calculated exactly. The chip thickness changes together with the exit angle when using constant feed rate, so the effect of chip thickness has to be considered as well. The exact value of chip thickness can also be determined only numerically, but there are many known approximations that can be applied in practice for the cases when small feed rates are used.An optimal range of exit angle can be estimated with an experiment that is presented in the paper. For circle and line contour elements the path of the tool centre can be determined exactly, which meet the criteria of a given exit angle. The two paths of tool centre belonging to two different exit angles form a closed area. If the tool centre during machining moves inside of this area, then the exit angle remains in the specified range. Depending on the complexity of the workpiece the path of tool centre cannot be always determined for a given exit angle criteria.The paper presents several paths of tool centre belonging to various exit angles for a special workpiece geometry that was used for the experiments. The results of the experiments are presented, which illustrate the efficiency of the method.