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Cutting mechanics

Five-axes milling machine

Cutting velocity V is the peripheral speed of the cutter and is defined by V = πDN, where D is the cutter outer diameter, and N is the rotational speed of the cutter. As in the case of turning, cutting speed V is first calculated or selected from appropriate reference sources, and then the rotational speed of the cutter N, which is used to adjust milling machine controls, is calculated. Cutting speeds are usually in the range of 0.1 ~ 4 m/ s, lower for difficult-to-cut materials and for rough cuts, and higher for non-ferrous easy-to-cut materials like aluminum and for finishing cuts. Three types of feed in milling can be identified: feed per tooth fz: the basic parameter in milling equivalent to the feed in turning. Feed per tooth is selected with regard to the surface finish and dimensional accuracy required. Feeds per tooth are in the range of 0.05 ~ 0.5 mm/ tooth, lower feeds are for finishing cuts; feed per revolution fr: it determines the amount of material cut per one full revolution of the milling cutter. Feed per revolution is calculated as f r = fzz z being the number of the cutter’s teeth; feed per minute fm: Feed per minute is calculated taking into account the rotational speed N and number of the cutter’s teeth z, fm = fzzN = frN

Feed per minute is used to adjust the feed change gears. Milling is an interrupted cutting operation: the teeth of the milling cutter enter and exit the work during each revolution. This interrupted cutting action subjects the teeth to a cycle of impact force and thermal shock on every rotation. The tool material and cutter geometry must be designed to withstand these conditions. Cutting fluids are essential for most milling operations. The milling operation is distinguished from other machining operations on the basis of orientation between the tool axis and the feed direction, however, in other operations, such as drilling, turning, etc., the tool is fed in the direction parallel to axis of rotation.

TOS Olomouc F2V-R Knee-Type milling machine is designed for milling and drilling operations of small and medium-size components of up to 200 kg weight occurring in all branches of the engineering production. The milling head with the spindle seated in the slide sleeve can be inclined in the longitudinal plane of the table. The wide range of speed and feeds enables effective milling of all metals with tools made from a high-speed steel or a hard metal.