Some Preliminary Metallurgical Studies on Grain Size and Density of Work Material used in Micro Turning Operation

Abstract

One important process in tool based micro machining technology is CNC micro turning which has the capability to produce 3D structures on micro scale. The major drawback of micro turning process is that the machining force influences machining accuracy and the limit of machinable size and shape. Therefore, the control of reactive force during cutting is an important factor in improving machining accuracy. The properties of work material significantly affect the cutting force generated during turning process. Commercially available metal rods are inhomogeneous and hence, qualifying the right material is very crucial in micro turning. Unlike plates, the properties like grain size and density vary significantly at different locations of the round bars. Hence, it is found very important to systematically find right material for micro turning from the commercially available rods. In present study, an attempt has been made to study the grain size and density of blank material from different locations of a larger diameter shaft. The work material selected is a 32 mm diameter shaft of commercial brass, a non ferrous alloy of copper and zinc. Five samples from different radial locations are cut from this shaft. It is found that grains are coarser at centre and finer towards the periphery of the shaft. Further, local density is less at centre and high at periphery of the shaft.