THE PERFORMANCE OF LOW COST CUTTING TOOLS WHEN MACHINING HARDENED STEEL OF 60 HRC

Hard turning is a topic of great interest in today’s industrial production and scientific research. The hard turning technology has the potential for improving productivity against grinding in the manufacturing process. Today, tool manufacturers are constantly developing new combinations of coatings and substrates to precisely match different workpiece materials and operations. Nevertheless, the suitability of coated mixed ceramic (AI2O3 + TiCN) cutting tools when hard turning AISI D2 cold work tool steel (60 HRC) is yet to be investigated. An understanding of the tool life and wear mechanisms, surface integrity produced by coated mixed ceramic cutting tools will give an alternative to the manufacturing industries to exploit low costs cutting tools in hard turning of AISI D2 (60 HRC). The noticeable trend of the tool life was observed at test conditions where the cutting speed is at 100 m/min instead of 140 m/min or 200 m/min. The wear mechanism of coated mixed ceramic cutting tools with TiN is subjected to abrasion, adhesion, chipping and notching, especially when machining at high cutting speed of 200 m/min

Human toxocariasis: contribution by Brazilian researchers

In the present paper the main aspects of the natural history of human infection by Toxocara larvae that occasionally result in the occurrence of visceral and/or ocular larva migrans syndrome were reviewed. The contribution by Brazilian researchers was emphasized, especially the staff of the Tropical Medicine Institute of São Paulo (IMT)

Hard Turning of Stainless Steel using Wiper Coated Carbide Tool

In recent years, tool manufacturers provide wiper geometry on cutting tools for turning applications with the purpose of increasing productivity and improving surface finish. Despite the potential added values, the use and study on wiper inserts are still lacking in quantity. This current study focuses on the performance of wiper coated carbide insert in hard turning with respect to tool life and surface finish. AISI 420 stainless steel hardened to 47–48 HRC was hard turned at various speeds and feeds ranging in finish turning parameters. Results showed that the maximum tool life of 18 min was achieved and the tool life decreased at higher cutting speeds and feeds. Wear occurred at both the rake and flank faces with crater formation exposing the carbide substrate indicating more severe wear on the rake face. The wiper coated carbide tool resulted in very fine surface finish, much better than the theoretical values

Comparison of IgG-ELISA and IgG4-ELISA for Toxocara serodiagnosis

Diagnosis of human toxocariasis, caused by Toxocara canis or Toxocara cati, normally relies on a combination of the presence of clinical signs and symptoms backed by positive serology. The use of Toxocara excretory-secretory antigen (TES) in ELISA assays increases the test specificity. However, in tropical countries where soil-transmitted helminths are endemic, cross-reactivity from antibodies to these intestinal parasites poses a significant limitation for Toxocara serodiagnosis. To increase the specificity of serodiagnosis, we compared the use of IgG-ELISA to the use of IgG4-ELISA using commercially manufactured TES-coated plates. The sensitivity of the IgG-ELISA was 97.1, while that of the lgG4-ELISA was 45.7; the specificities were 36.0 and 78.6, respectively. The study shows that employing both assays can improve the serodiagnosis of toxocariasis. An IgG4 immunoassay would also be useful in the secondary screening of antigen clones in the effort to develop improved serological tests for toxocariasis. (C) 2004 Elsevier B.V. All rights reserved

Comparative analysis of ITS1 nucleotide sequence reveals distinct genetic difference between Brugia Malayi from Northeast Borneo and Thailand

Brugia malayi is one of the parasitic worms which causes lymphatic filariasis in humans. Its geographical distribution includes a large part of Asia. Despite its wide distribution, very little is known about the genetic variation and molecular epidemiology of this species. In this study, the internal transcribed spacer 1 (ITS1) nucleotide sequences of B. malayi from microfilaria-positive human blood samples in Northeast Borneo Island were determined, and compared with published ITS1 sequences of B. malayi isolated from cats and humans in Thailand. Multiple alignment analysis revealed that B. malayi ITS1 sequences from Northeast Borneo were more similar to each other than to those from Thailand. Phylogenetic trees inferred using Neighbour-Joining and Maximum Parsimony methods showed similar topology, with 2 distinct B. malayi clusters. The first cluster consisted of Northeast Borneo B. malayi isolates, whereas the second consisted of the Thailand isolates. The findings of this study suggest that B. malayi in Borneo Island has diverged significantly from those of mainland Asia, and this has implications for the diagnosis of B. malayi infection across the region using ITS1-based molecular techniques

High-speed machining of martensitic stainless steel using PcBN

The performance of PcBN cutting tool during its application in the mass production of components made from AISI 440B stainless steel has been considered. The experimental tests have been performed at cutting speed ranging between 350–500 m/min at dry cutting conditions. The machining operations that have been explored included facing, turning, grooving and boring and the 3D topography of the machined surface presented. The results show that good surface finish similar to grinding and dimensional accuracy can be achieved with PcBN tools.Рассмотрены рабочие характеристики режущего инструмента, оснащенного поликристаллическим кубическим нитридом бора (КНБ), используемого в массовом производстве изделий из нержавеющей стали AISI 440B. Экспериментальные испытания проводили при скорости резания в диапазоне от 350 до 500 м/мин в условиях сухого резания. Представлены операции обработки, включающие обточку торца, точение, прорезание канавок и сверление, а также 3D-топография обработанной поверхности. Результаты показывают, что, применяя в инструментах поликристаллический КНБ, можно достичь хорошего качества обработки поверхности и точности размеров, таких же как при шлифовании.Розглянуто робочі характеристики ріжучого інструменту, оснащеного полікристалічним кубічним нітридом бору (КНБ), що використовують в масовому виробництві виробів з нержавіючої сталі AISI 440B. Експериментальні випробування проводили при швидкості різання в діапазоні від 350 до 500 м/хв в умовах сухого різання. Представлено операції обробки, що включають обточування торця, точіння, прорізання канавок і свердління, а також 3D-топографія обробленої поверхні. Результати показують, що, застосовуючи в інструментах полікристалічний КНБ, можна досягти хорошої якості обробки поверхні і точності розмірів, таких же як при шліфуванні

Structural Damage Identification Using Response Surface-Based Multi-objective Optimization: A Comparative Study

Non-destructive structural damage identification (SDI) and quantification of damage are important issues for any engineering structure. In this study, a comparative assessment of the damage identification capability of different design of experiment (DOE) methods (such as, 2k factorial design, central composite design, Box–Behnken design, D-optimal design and Taguchi’s OA design) used in response surface methodology (RSM) has been carried out. Three different structures (simply supported beam, spring mass damper system and fibre reinforced polymer composite bridge deck) have been used for various single and multiple damage conditions to access the comparative ability of the aforementioned methods in identifying damage addressing two critically important criteria: accuracy and computational efficiency. The study reveals that central composite design and D-optimal design are most recommendable among the five considered DOE methods for SDI. Two different input parameter screening methods (sensitivity analysis using RSM utilizing 2k factorial design and D-optimal design, general sensitivity analysis) have been explored in this study, and their comparative performance is also discussed. It is found that both the methods used in sensitivity analysis for the purpose of input parameter screening in the damage identification process work satisfactorily. Performance of RSM-based damage identification algorithm for different DOE methods under the influence of noise has also been addressed in this paper.</p