| Summary: | 碩士 === 國立清華大學 === 動力機械工程學系 === 88 === The terms ''High Speed Machining'' (HSM) and ''High Speed Cutting'' (HSC) have been used recently to describe end milling with small diameter tools at high rotational speeds, typically 10,000-100,000 rpm. HSM was first applied in the aerospace industry for the machining of light alloys, notably aluminum. In recent years the mould and die industry has begun to use the technology for the production of components, including those manufactured from hardened tool steels. The study is performed an experimental investigation of high speed (5,000 - 15,000 rpm) ball milling of hardened (hardness 40 - 53 HRC) JIS SKD61 (AISI H13) tool steels using TiAlN coated cemented tungsten carbide tooling. The machining parameters involved were; highest cutting speeds in the range of 49 to 205 m/min, feed per tooth variation from 0.025 to 0.05 mm/tooth, axial depth of cut from 0.25 up to 0.5 mm, and radial depth of cut of 0.2 mm. Dry and flood coolant cutting conditions were used. The effects of different process parameters on the tool wear, tool life, chip formation, cutting force and workpiece surface finish have been studied. The experiment results show that higher cutting speed is recommended especially when workpiece hardness of 53 HRC was machined. Dry cut is also recommended. An unusual phenomenon observed, tool worn out slower at the higher spindle speed (higher cutting speed) when workpiece hardness of 53 HRC was machined.
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