Análise da força de corte e rugosidade no torneamento de ferro fundido cinzento utilizando sistemres

Abstract

Turning is a conventional machining operation that is based on chip removal through shear caused by a cutting edge. During plastic deformation of the material for chip formation, more than 95% of the mechanical energy supplied by the machine is transformed into heat. This concentration of thermal energy in a small region produces high temperatures in the chip-tool contact, which for turning gray cast iron vary in a range from 600 ºC to 900 ºC, depending on the machining parameters. This high temperature on the cutting tool has a harmful effect as it enhances the wear mechanisms, thus reducing its useful life. To control this problem, several solutions are used industrially, which include the use of cutting fluid, the minimum amount of lubricant technique (MQL) and the development of new materials for cutting tools. This work aims to evaluate the effect of using internal coolant tools (ICT) on the cutting force and roughness of the workpiece. Through the electrical discharge machining, cooling channels were manufactured in the carbide tools so that water at 2 ºC circulated internally in a closed cycle. Machining tests were carried out on a FC-300 gray cast iron bar, comparing the use of ICT with the no internal coolant tool (NICT). A mixed factorial experimental design was used, with two levels for cutting depth factor (1.0 and 1.5 mm) and use of coolant (ICT or NICT), and three levels for cutting speed (150, 200 and 250 m/min), totaling 12 different conditions. The output variables were cutting force and roughness Ra and Rq. Among the main results are: a reduction in Ra from 4.8% to 14.9% and in Rq from 5.5% to 20.0%, when comparing ICT with NICT; the use of ICT resulted in a drop of 0.8% to up to 21.07% in cutting force compared to NICT.