Experimental investigation of rotary turning processes for metal alloys

Official URL: http://risc01.sabanciuniv.edu/record=b1534440 (Table of Contents)

The demand of aerospace, defence, medical and chemical industries to special alloys have been increasing recently in application requiring high performance. Ability to retain their high mechanical and chemical properties even at elevated temperatures makes superalloys such as ni-base, ti-base, co-base, ideal for use in these industries. Even though machining is one of the important production methods of these alloys, these alloys show formidable challenges to cutting tools. Due to their unique inherent properties, cutting tools expose to higher cutting temperatures and higher stresses during process resulting premature failure, hence these alloys are called difficult to machine alloys. As a result, machining of these alloys with conventional processes is unproductive, time consuming and costly. Rotary turning processes can be a good solution for machining these superalloys. Rotational motion of cutting insert around its axis during process provides fresh portion of cutting edge to cutting region continuously. As a result, generated heat is dissipated around cutting edge and heating of a particular portion of tool is prevented. This reduces the thermally activated wear mechanism on cutting edge resulting prolonged tool life and increasing machinability of these alloys. The main aim of this thesis is to understand the performance of self-propelled rotary turning (SPRT) and actively driven rotary turning (ADRT) tools on metals especially for difficult to cut alloys. Tool life, generated forces, surface roughness and circularity of workpiece are analyzed for various cutting and cooling conditions for rotary turning processes. The effects of tool inclination angle, tool velocity and cooling conditions on tool wear behavior are examined for ADRT process. Then these results are compared with conventional turning process results to see the process advantages. Tool rake face temperature measurements are conducted for ADRT process for various materials in order to correlate the tool life results with cutting temperature. In addition, the difference in performance of SPRT and ADRT is analyzed for the same testing materials and cutting conditions.