Showing papers by "Carlos Henrique Lauro published in 2014"

Experimental investigation on finish intermittent turning of UNS M11917 magnesium alloy under dry machining

Abstract: An experimental investigation on finish intermittent turning of UNS M11917 magnesium alloy under dry machining is presented. The objective of the study is the analysis of the chip morphology, surface quality and temperature when varying cutting conditions. The intermittent cutting process is analysed using three different workpieces (one continuous and two discontinuous). The experimental plan is based on full factorial designs. Main results of the investigation include the identification of the feed rate as the most important parameter to explain the surface roughness, while no clear influence was found for the cutting speed and slot width. The maximum temperature measured on the tool during the tests was below 50 °C in all of the tests. These low temperature values are explained by the low machining times, depths of cut and cutting speeds used. Thus, for the range of the cutting parameters tested, finish operations can be performed using dry machining under safe conditions. In addition, it was identified that the increase of the depth of cut and feed rate led to higher maximum temperatures, while the increase of the slot width led to lower values. Finally, the morphology of the chips can be classified as segmented chips, including the arc, elemental and spiral chips. Thus, in terms of machining, these chips can be considered as favourable, but, in terms of ignition, these chips are more likely to ignite.

Analysis of the Forces in Micromilling of Hardened AISI H13 Steel with Different Grain Sizes Using the Taguchi Methodology

Abstract: The micromachining process has been applied to the free form and micromolds markets. This has occurred due to the growth in demand for microcomponents. However, micromachining of hardened steels is...

Definition of the Temperature and Heat Flux in Micromilling of Hardened Steel Using the Finite Element Method

Abstract: This paper shows the influence of the mesh size on the heat flux in the micromilling process The definition of the heat flux was based on the inverse heat conduction method (IHCM), applying the finite element technique with the Eulerian–Lagrangian approach The micromilling was simulated with a cutter of 05 mm and four mesh sizes The input parameters were two feed rates, two cutting speeds, and two radial depths of cut Experiments were designed to verify the more significant input parameters on the heat flux and temperature The results demonstrated that the mesh size has great influence on the responses The values for heat flux can vary more with the mesh size than with the cutting parameters On the other hand, the cutting speed was the parameter with the least significance The adjusted data using IHCM for temperature, heat flux, and the convection coefficient corresponded with the traditional values

Analysis of Surface Roughness in Micro Milling of Ti-6Al-4V Titanium Alloy

Abstract: This work shows a study on the micro milling of Ti-6Al-4V Titanium alloy where the effect of tool wear on the surface finish of the machined part was analyzed New and worn micro cutters were applied to produce grooves with 05 mm of width and 0025 mm of heights The surface roughness was measured in the Ra and Rz values and the results showed that the surface roughness was not influenced by the tool’s condition However, when new tools were used the increase of cutting speed generated an improving of the surface roughness and the same effect occurred with the decrease of feed rate

Influência da variação do tamanho de grão austenítico na qualidade superficial no processo de microfresamento do aço AISI H13 endurecido Influence of the austenite grain size variation on the surface finishing in the micromilling process of the hardened AISI H13steel

Abstract: The focus of this work was to study the influence of austenite grain size in the surface finish during micro milling of hardened steels. Work pieces with hardness of 46 HRC and different grain sizes were milled with micro end mills with a diameter of 0.5 mm. The experimental tests were carried out with two cutting speeds and two feed rates. The results were evaluated using an analysis of variance, and they demonstrated that the cutting speed and the feed rate have no influence on the responses surface roughness Ra and Rz. Thus, it could be observed that the most important factor was the grain size that influenced the roughness Ra and Rz, significantly. Moreover, it was also observed that the interaction of input parameters did not show significant influence on the response surface roughness Ra and Rz.

Influência da variação do tamanho de grão austenítico na qualidade superficial no processo de microfresamento do aço AISI H13 endurecido

Abstract: O foco deste trabalho foi o estudo da influencia do tamanho de grao austenitico na qualidade superficial durante o processo de micro fresamento de acos endurecidos. Corpos de prova com durezas de 46 HRC e com diferentes tamanhos de grao foram fresados com micro fresas de topo com 0,5 mm de diâmetro. Nos testes experimentais foram empregadas duas velocidades de corte e dois avancos por dente. Os resultados foram analisados empregando-se uma analise de variância e demonstraram que a velocidade de corte e o avanco nao tiveram influencia no comportamento da rugosidade considerando os parâmetros Ra e Rz. Dessa forma, pode-se observar que o fator mais importante foi o tamanho de grao que influenciou significativamente os valores de rugosidade Ra e Rz. Alem disso, observou-se tambem que a interacao das variaveis de entrada nao demonstrou influencia significativa sobre as respostas rugosidade Ra e Rz.