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Geometrical accuracy of workpieces manufactured in CNC technology is dependent on many different factors, such as the parameters of a cutting process. The most significant are: cutting velocity vc and feed rate vf but also proper cooling and appropriate rigidity of a machine tool. Values of these parameters are dependant on the kind of a workpiece and on the applied tools. Considering shape complexity of a workpiece, dimensional and shape errors can appear, for example deviations of flatness, rectilinearity and radius roundness, etc. To avoid errors connected with geometrical profile, the parameters of machining should be selected in such way to obtain maximal value of quality rating of a product considering its shape and dimension. The aim of this paper is to evaluate the correction of feed rate (vf ) influence on radius errors of a workpiece's corners and to define the relation between technological conditions of cutting process and the actual shape of radius after machining. In theoretical part, the influence of different factors on the accuracy of cutting on CNC machine was included; the main focus was on the accuracy of cuttings the corners with different radii. The practical part consists of corner's radius errors measurements with the usage of coordinate measuring machine and complex analysis of research findings. The findings were presented in the form of diagrams and charts. Because of the fact that the feed rate influences the global time of workpieces' machining, the findings presented in this paper enable the production engineers to choose the optimal value of feed rate during the cutting of corners on CNC machines. It is very important during machining of matrices which construction consists of many corners with given radii that are placed between perpendicular and slant walls.
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