Общий каталог ZCC-CT 2019 - страница 459

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TurningMillingDrillingTechnicalInformationIndex Technical information Technical information – turning A Turning toolsThree effects of cutting condition for turning Vc Today short machining time, long tool life and high machining accuracy is expected from modern tools. Based on the machine performance, material shape and hard- ness of the components the right choice of tool and cutting conditions are the premise for a successful machining process. Cutting speed, feed rate and depth of cut are what we call the “Three effects of cutting”. ap f B 1. Cutting speed (Vc) Cutting speed is defined as the rate (or speed) that the material moves past the cutting edge of the tool. The unit for Vc is meter per minute [m/min]. Cutting speed influence: Cutting speed is one of the three important effects of turning and has influence on tool life. Increasing the cutting speed also increases the cutting temperature and that decreases the tool life. Depending on the hardness and type of material the cutting speed varies. Therefore to choose a suitable grade for the cutting speed is necessary. In general situation, when cutting speed is increased by 20 % the tool life will be reduced ½; when the cutting speed is increased by 50 % the tool life decreases 1⁄5. Lower cutting speed results in vibration which will shorten tool life. C 2. Feed rate (f) In turning application feed rate is the distance the tool holder moves per work piece revolution. That has influence to the surface quality. The unit for feed rate is millimetre per revolution [mm/rev] D Feed rate influence: Decreasing the feed rate will increase flank wear and tool life will be shortened. Increasing the feed rate increases the cutting temperature and also flank wear. On the other hand the efficiency will be improved. 3. Depth of cut (ap) The depth of cut refers to the half different value between the diameter of the unmachined and machined work piece. The unit is millimetre [mm]. Depth of cut influence: Changing depth of cut has no big influence to the tool life. Machining hardened layer with small depth of cut results in friction and short tool life. Machining uncut surface or cast iron material, choose maximum depth of cut according to the machine power so that the cutting edge and corner radius is out of the hardened layer. That helps to prevent chipping and abnormal wear. E A 454