A Method of Stability Lobes Building in Ball End Milling of Inclined Surfaces. Part 2: Lobes building

A method of creating a stability lobes diagram in ball end milling of inclined surfaces. Part II: Creating a lobe diagram. In this paper was proposed a semianalytic method of creating a stability lobes diagram for upward and downward ball end milling of surface inclined with some angle. The paper shows test results for method approbation. Tests were carried out for upward slot machining of surfaces inclined with the lead angles 30° and 45°. The results confirmed an efficacy of the method in a narrow range (1.5-2 times) of spindle speed values. It occurs due to the considerable changes of cutting force when the cutting velocity increases. Also in this paper were adduced proofs that machining process of the surfaces with smaller lead angle stays stable at greater values of radial cutting depth. In our opinion, it is related to the lot of factors, particularly greater value of the angle of contact in the case of machining of surface with the smaller lead angle value leads to decreasing of interrupted cutting. Also in the case of machining of surface with the smaller lead angle value radial component of the cutting force has lesser degree of impact and as a result there is a lesser of tool bending.