Evaluation of cutting force and surface roughness in high-speed milling of compacted graphite iron

Abstract

Abstract. Compacted Graphite Iron, (CGI) is known to have outstanding mechanical strength and weightto-strength ratio as compared to conventional grey cast iron, (CI). The outstanding characteristics of CGI is due to its graphite particle shape, which is presented as compacted vermicular particle. The graphite is interconnected with random orientation and round edges, which results in higher mechanical strength. Whereas, graphite in the CI consists of a smooth-surfaced flakes that easily propagates cracks which results in weaker and brittle properties as compared to CGI. Owing to its improved properties, CGI is considered as the best candidate material in substituting grey cast iron that has been used in engine block applications for years. However, the smooth implementation of replacing CI with CGI has been hindered due to the poor machinability of CGI especially at high cutting speed. The tool life is decreased by 20 times when comparing CGI with CI under the same cutting condition. This study investigates the effect of using cryogenic cooling and minimum quantity lubrication (MQL) during high-speed milling of CGI (grade 450). Results showed that, the combination of internal cryogenic cooling and enhanced MQL improved the tool life, cutting force and surface quality as compared to the conventional flood coolant strategy during highspeed milling of CGI.

Machinability of high strength molybdenum-refined graphite grey cast iron and conventional vermicular automobile engine heads using heptagonal and double-sided carbide inserts

“…According to Agunsoye et al [2013], to understand the mechanical properties of cast irons, it is necessary to understand the microstructure formation in these materials and how the chemical composition variables, or processing, affect the microstructure. This knowledge usually bares to the manufacturer of the piece, but a broad discussion of some fundamentals and limitations, including how alloying elements in uences the machinability, helps the designer in the perception of what is possible to achieve with cast irons [Suhaimi et al, 2017].…”

Archives of Metallurgy and Materials

“…in terms of its microstructure and combination of mechanical and physical properties, CGi falls between cast iron with flake-like graphite and cast iron with spheroidal graphite. Compared to conventional grey cast iron, CGi has almost double tensile strength and fatigue strength, 38% higher elastic modulus and 8% smaller thermal conductivity [5]. This beneficial combination of materials properties justifies a wide application of CGi in manufacturing of components for trucks, tractors, passenger cars and marine diesel engines [2][3][4] and more recently, for the production of cylinder blocks for diesel engines or railway brake discs [6][7][8][9][10].…”