No abstract

No abstract

No abstract

No abstract

No abstract

No abstract

Two face milling cutter systems, both with PCBN (polycrystalline cubic boron nitride) tools, were used to study burr formation in high-speed machining of grey cast iron under various cutting conditions. Surface roughness parameters R a and R t , tool life (based on¯ank wear, VB max ) and burr formation (length of the burr, h) were recorded and used for comparing machining performance. The best performance in terms of tool life and surface roughness was obtained with the milling cutter system consisting of 24 teeth and 24 square wiper inserts. Machining with this cutter con®guration produced acceptable surface roughness values, well below the rejection criterion, after machining a batch of 3000 motor blocks in addition to achieving a signi®cant reduction in the burr length. NOTATIONdoc depth of cut (mm) f z feed per tooth (mm) h maximum roughness height (mm) PCBN polycrystalline cubic boron nitride R a average roughness (mm) R t maximum roughness height (mm) V c cutting speed (m/min) V f feed rate (mm/min) VB max maximum¯ank wear (mm) m exit angle (deg) À r approach angle (deg)

Many machining researches are focused on cutting tools mainly due to the wear developed as a result of high temperatures generated that accelerate thermally related wear mechanisms, consequently reducing tool life. Cutting fluids are used in machining operations to minimize cutting temperature although there is no available indicator of their cooling ability. In this study, a method to determine the cooling ability of cutting fluids is proposed. A thermocouple technique was used to verify the chip‐tool interface temperature of various cutting fluids during turning operation. The method consists of measuring the temperature drop from 300°C up to room temperature after heating a standardised AISI 8640 workpiece and fixing it to the chuck of a lathe and with a constant spindle speed of 150 rpm the cutting fluid was applied to a specific point. The temperature was measured and registered by an infrared thermosensor with the aid of an AC/DC data acquisition board and a PC. The convective heat exchange coefficient, h, was determined and used to classify the cooling ability of the cutting fluids. The machining tests showed that the application of the fluid with better cooling ability will not always guarantee lower chip‐tool interface temperature.