An Experimental Investigation of Machinability of Graphitic Cast Iron Grades; Flake, Compacted and Spheroidal Graphite Iron in Continuous Machining Operations

Abstract

In this study the machinability of different grades of cast iron has been studied in terms of cutting temperatures, cutting forces, tool life, deformed chip thickness and contact length in different continuous machining operations. The tests performed were: external turning, boring and face turning. Pearlitic Flake Graphite Iron (FGI), Compacted Graphite Iron (CGI) and Spheroidal Graphite Iron (SGI) materials were selected for making the experiments. Later the machinability was also compared with ferritic SGI material. The cutting temperature has been measured with the help of embedded thermocouple inserts. These inserts were having 2 junctions; 0.55 and 1.2mm away from the cutting edge on the clearance face. It was found that the cutting temperature on the clearance face has not shown any significant difference for different grades of cast irons. However, the tool life and the cutting forces have shown significant differences. The face turning tests were performed in both dry and wet conditions to see the importance of cutting fluids for different grades of cast iron. It has been seen that the CGI and SGI require cutting fluid in a continuous machining operation. Later the wear mechanisms of different grades were also studied for dry and wet conditions in a boring operation. Both CGI and SGI have shown adhesion as a wear mechanism under dry conditions as compared to abrasive wear in wet conditions with a cutting speed of 300 m/min. The results can be input to designing a suitable insert for CGI and SGI and highlight the importance of using cutting fluids while machining CGI and SGI in continuous cutting operations.