Research On Milling Performance Of Austempered Ductile Iron

Austempered Ductile Iron (ADI in short) is widely used in aerospace, ships, vehicles and heavy industry for its perfect mechanical property. Austempering heat treatment process significantly lowers mechanical cutting performance of nodular cast iron at the same time of improving its mechanical properties which seriously restricts the broad application of ADI, and which is especially serious in our country.In this dissertation, three groups of ADI is researched which austempering temperature is 250℃,300℃,350℃and quench time is one hour respectively. Through dry milling tests for ADI using TiAlN and TiSiN coating tools from Misumi Ltd, the influences of austempering temperature, tools, cutting speed, feed per teeth, cutting width and cutting depth on cutting force, tool wear and surface roughness during the milling process of ADI are researched. Based on fuzzy subtractive clustering method, a milling force prediction model is established according to test data, which can be used to determine milling parameters for ADI material.The main research works done are listed as follows.1. For the three groups of ADI, influences of austempering temperature and cutting tools on milling force are researched. Firstly, the effects on milling force of four milling factors, such as cutting speed, feed per-teeth, cutting width and cutting depth are investigated with orthogonal test method. Then influence of each milling factor on milling forces is discussed with single-factor method.2. Three groups of ADI materials are milled with two coating tools respectively, Tool flank wear state is recorded during milling. Influences of austempering temperature and tool material on tool flank wear are analyzed. Flank wear morphology of tool after milling is observed using S-4700 scanning electron microscope (SEM).Tool wearing mechanism is analyzed. 3. Surface roughness of workpiece milled by two tools is measured with 2205 surface roughness measuring instrument. The influences on workpiece of austempering temperature, tool material and cutting parameters surface roughness are analyzed.4. Based on fuzzy subtractive clustering model, a milling force prediction model for austempering temperature, tool material and cutting parameters is established.The dissertation provides reference data for finish cutting parameters of three kinds of ADI material which austempering temperature is 250℃,300℃and 350℃respectively. Milling force prediction model based on fuzzy subtractive clustering provides theoretical basis for the variance of milling force with technology for heating processing parameter, cutting tool and cutting parameter. The difference between forecast milling force and testing data is below 8.86%, which indicates that milling force mode is believable and can be used to forecast milling force of real milling process.