Uma contribuição a melhoria do processo de fresamento de ferro fundido vermicular - CGI

Abstract

GABALDO, Sander, A contribution to the improvement of the milling process machining compacted graphite iron -CGI, Campinas,: Mechanical Engineering Faculty, State University of Campinas, 2009. 136 p. Thesis (MSc).Since the beginning of this century, researches about the development of diesel engines have been intensified, aiming to increase its energy efficiency and to reduce the levels of emission of pollutants. One the way to increase this efficiency is to increase the peaks of pressure of fuel explosion in the combustion chamber. The grey casting iron material is the most common material used for the manufacturing of diesel engine blocks. However, to increase the pressures in the combustion chamber when this kind of alloy is used, it is necessary to increase the wall thickness of the blocks, what raises its weight and consequently, does not fulfill with the specified requirements. Thus, the compacted graphite iron (CGI) appears as an alternative material for such application. It has characteristics of heat conductivity and damping similar to the casting iron, however, with superior mechanical properties making possible the manufacturing of small and consequently, light engines and also with better performance, without considering the reduction of the environmental pollution for gases and noises. However the use of the CGI presents as disadvantage its worse machining when compared with the grey casting iron, stimulating research and development of machining techniques and, development of the cutting materials, where this thesis is inserted. The objective of this thesis is to analyze the influence of the micro geometries of the cutting edge (tested positive and flat geometry), cutting material (tested hard material, ceramic Si 3 N 4 with or without coating) and cutting speed in the finishing operation of the fire face of the engine made of CGI. As output variables we used tool life, cutting power and surface roughness of the workpiece. Among the main result we could say that the most negative tool presented the longest tool life and carbide material is better than ceramic (with or without coating) in terms of tool life in the milling of this kind of workpiece.x

Estudo do desempenho de ferramenta de corte no processo de mandrilamento em ferro fundido vermicular - CGI

“…Em contrapartida, ferramentas de metal duro são consideradas uma melhor opção para processo de usinagem em fresamento de ferro fundido vermicular. O mecanismo de desgaste por difusão é muito acentuado em ferramentas de cerâmica a base de nitreto de silício (GABALDO, 2009).…”