Influence of HSM cutting parameters on the surface integrity characteristics of hardened AISI H13 steel

The purpose of this study is to evaluate the influence of the cutting parameters of high-speed machining milling on the characteristics of the surface integrity of hardened AISI H13 steel. High-speed machining has been used intensively in the mold and dies industry. The cutting parameters used as input variables were cutting speed (v c), depth of cut (a p), working engagement (a e) and feed per tooth (f z ), while the output variables were three-dimensional (3D) workpiece roughness parameters, surface and cross section microhardness, residual stress and white layer thickness. The subsurface layers were examined by scanning electron and optical microscopy. Cross section hardness was measured with an instrumented microhardness tester. Residual stress was measured by the X-ray diffraction method. From a statistical standpoint (the main effects of the input parameters were evaluated by analysis of variance), working engagement (a e) was the cutting parameter that exerted the strongest effect on most of the 3D roughness parameters. Feed per tooth (f z ) was the most important cutting parameter in cavity formation. Cutting speed (v c) and depth of cut (a p) did not significantly affect the 3D roughness parameters. Cutting speed showed the strongest influence on residual stress, while depth of cut exerted the strongest effect on the formation of white layer and on the increase in surface hardness.

Mudança estrutural e mercado de trabalho no Brasil

Structural changes and labor market in Brazil. In the present article, we attempt to identify the sources of the changes in the labor schooling level in the three main sectors of the Brazilian economy: manufacturing, services and agriculture. It was verified that, despite the changes in the product and employment among sectors, mainly in the 1990s, the relative demands for qualified workers has not experimented significant changes. Moreover, in the periods in which schooling has increased more, the workers' wage has decreased more. This fact suggests that the increase in labor qualification was mainly due to the increase of this factor supply. The structural changes had contributed, in general, in a marginal and negative way to labor force level of qualification demand in all the three sectors.

Fragmentação geopolítica: uma análise estrutural das propostas de separatismo no Brasil

Este trabalho tem por objetivo dar luz ao debate sobre a criação dos novos entes federativos, trazendo elementos objetivos sobre a caracterização socioeconômica dos novos espaços geopolíticos e seus respectivos papéis no novo contexto espacial do sistema inter-regional brasileiro. O artigo traz resultados inéditos para a discussão, buscando, inicialmente, identificar padrões hierárquicos e de dependência espacial e produtiva neste novo contexto federativo. Tais resultados subsidiama analise subsequente dos impactos da nova configuração das transferências constitucionais, que identifica pormeio de simulações comummodelo inter-regional de insumo-produto especialmente calibrado para as 33 regiões consideradas no estudo, não apenas os potenciais ganhadores e perdedores, mas também os mecanismos de interação espacial subjacentes a estes processos.