Hard Turning of Sintered Cemented Carbide Parts: A Shop Floor Experience

AbstractMachining hardened steel has been a recurring issue in the literature when tools with defined geometry cutting edges are used. It is well known the use of cemented carbides to produce cutting tools. It is also well known that this occurs before applying sintering process, to facilitate the production of special tools or specific kind of parts, which will be sintered later. What is not very known is the cutting of cemented carbides to produce special kind of parts used when high hardness, high compression resistance, high surface quality and tight tolerances are demanded. To meet such requirements is necessary to machine the pieces after sintering. Despite being a satisfactory alternative, the grinding process could not meet such requirements and, moreover, probably is more expensive. The purpose of this work is to develop an experience that, by gathering data from an industry shop floor that choose not to be identified, show the feasibility of turning sintered cemented carbide. The results showed that besides to be viable, turning process could machine workpieces with tight tolerances and excellent surface roughness

Root system traits and its relationship with photosynthesis and productivity in four maize genotypes under drought

The present study combined evaluations of agronomic parameters such as roots morphometry (using the WinRhizo program) and leaf gas exchange, in order to detect features in the root system which allow the maintenance of photosynthetic rates and productivity in four maize genotypes contrasting for tolerance to water deficit (WD), two tolerant (DKB 390 and BRS1055) and two sensitive (BRS 1010 and 2B710). The genotypes showed similar tolerance to dehydration of leaf tissue, but the tolerant genotypes DKB 390 and BRS1055 presented higher photosynthetic rate and yield compared to the sensitive BRS 1010 and 2B710. Nevertheless, divergent strategies of adaptation to drought among tolerant genotypes were observed. The genotype DKB 390 presented physiological mechanisms in shoots responsible for minimizing water loss, which decreases the dependence of root adjustments to increase the absorption of water. In turn, the BRS 1055 genotype showed a drought avoidance strategy by producing fine roots associated with a higher leaf area

ENDOPARASITAS EM CÃES (Canis familiaris) NA CIDADE DE CURITIBA PARANÁ BRASIL

O presente trabalho analisa prospectivamente as infecções múltiplas e isoladas em cães de estudantes de quatro instituições de ensino de Curitiba PR, através de exames de 264 amostras de fezes, colhidas no período de abril a julho de 2000 e examinadas de acordo com a técnica de WILLIS (1921). A infecção isolada causada por Ancylostoma sp. foi observada em maior porcentagem, seguida da parasitose múltipla pela associação Ancylostoma sp./Toxocara sp. Enteroparasites in dogs (Canis familiaris) from Curitiba, Paraná, Brasil Abstract The present study demonstrates the multiple and isolated infections caused by enteroparasites in dogs belonged to students of four schools from Curitiba, PR, by examination of 264 fecal samples, collected from April to July, 2000, and analyzed by the WILLIS (1921) technique. The isolated infection by Ancylostoma sp. was the highest percentage observed, while Ancylostoma sp. and Toxocara sp. were the multiple parasites most frequently found

The effect of minimum quantity lubrication in the intermittent turning of magnesium based on vibration signals

The present work shows an experimental investigation on intermittent turning based on vibration signals. The dependence of vibrations on the feed rate, minimum quantity lubrication (MQL) flow rate and the type of the interruption of the workpiece is evaluated. The results indicate that a part of the vibrations depends on the flow rate of the MQL system and its interaction with the feed rate, finding no dependency on the type of interruption. The influence of the MQL system is greater when machining at the lower feed rate. In addition, a strong relation between surface roughness and vibrations is identified. However, this relation is quite different depending on the environment used. In general, under dry conditions, the higher the vibrations the higher the surface roughness, while the opposite occurs when the MQL system is used.publishe

LESÕES ANATOMOPATOLÓGICAS PRESENTES NA INFECÇÃO POR DIOCTOPHYMA RENALE (GOEZE, 1782) EM CÃES DOMÉSTICOS (CANIS FAMILIARIS,) LINNAEUS, 1758

Os autores descrevem as lesões anatomopatológicas de onze casos de parasitismo por Dioctophyma renale (Goeze, 1782), na cidade de Curitiba - PR, Brasil, constatados em necrópsias e achados clínicos em 1960 cães, no período de 1979 a 2004. Anatomopathologic lesions found in Dioctophyma renale (Goeze, 1782) infections in domestic dogs (Canis familiaris, LINNAEUS, 1758 Abstract The authors describe the anatomopathologic lesions of eleven cases of parasitism by Dioctophyma renale (Goeze, 1782), in Curitiba (PR, Brazil), found among 1960 necropsies carried out between 1979 and 2004 in dogs