In engineering technology there is always a problem to improve the accuracy of manufacturing parts. When machining, the arising forces cause both tool and work-piece displacements. In this paper we consider the influence of changing cutting forces on the machining errors that arise in face milling of flat surfaces. With this approach to machining, the cutting forces depend on the work-piece width, the cutter diameter, the number of teeth and their geometry, the mutual bracing of the cutter and the work-piece, and the application point of the resultant force. The paper presents the dependences, allowing us to calculate the cutting force in face milling. The proposed model allows us to determine the vector of deviations in the instantaneous (fixed in time) arrangement of the cutter teeth at the specific points of the surface machined, since different cutting forces act on each tooth on the arc of the contact with the surface. It is recommended that the resulting errors arising from the elastic deformation of the technological system should be evaluated by the vector field, which represents deviations of points of the real surface profile from their nominal position, due to action of the variable cutting forces within one turn of the cutter.

The development of computerization allows the development of mathematical models of physical processes with different methods of blade machining of machine parts. Modern programmable CNC machines have the ability to produce parts in an automated cycle, ensuring the requirements of the drawing. Control of the quality of processing of the main flat surfaces, which are technological and Assembly bases, should be considered in more detail. Their accuracy in accordance with the standards is determined by the shape deviations from the adjacent planes, size and relative position. The standards have instructions on how to create a virtual adjacent plane using adjustable supports and further scan the ordinates of its individual points to calculate the deviation of the form. To quantify the deviations of shape, size and location is not enough to have a field f, the vectors of which are defined from the geometric plane, given the nominal size, it is necessary to establish a base for their reference. The question of establishing bases for reference is not only of fundamental importance, since different bases can be obtained different values of deviations. The paper proposes a mathematical model for determining the named parameters of accuracy from the middle planes, which are determined by the calculated vectors at specific points of the treated surface when processing batches of blanks on milling machines face milling.