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Advanced ceramics: Evaluation of the mechanism of stock removal and ground surface quality

Bianchi, Eduardo Carlos; Da Silva, Eraldo Jannone; Neto, Luiz Daré; Da Silva Júnior, Carlos Elias
Fonte: Universidade Estadual Paulista Publicador: Universidade Estadual Paulista
Tipo: Conferência ou Objeto de Conferência
ENG
Relevância na Pesquisa
55.86%
The aim of this work is to evaluate the mechanism of stock removal and the ground surface quality of advanced ceramics grounded by a plane tangential grinding process with diamond grinding wheels. The analysis of the grinding performance was done regarding the cutting surface wear behavior of the grinding wheel for ceramic workpieces. The discussion about the results emphasized the wear mechanism of the grinding wheel cutting surface and the cutting phenomenology of the grinding process. The grounded surface was evaluated using Scanning Electron Microscopy (SEM). © 1999 Society of Automotive Engineers, Inc.

Advanced ceramics: Evaluation of the mechanism of stock removal and ground surface quality

Bianchi, E. C.; Da Silva, E. J.; Da Silva, C. E.; De Aguiar, P. R.; Valarelli, I. D.; Monici, R. D.
Fonte: Universidade Estadual Paulista Publicador: Universidade Estadual Paulista
Tipo: Artigo de Revista Científica Formato: 9-22
ENG
Relevância na Pesquisa
65.92%
The aim of this work is to evaluate the mechanism of stock removal and the ground surface quality of advanced ceramics machined by a surface grinding process using diamond grinding wheels. The analysis of the grinding performance was done regarding the cutting surface wear behavior of the grinding wheel for ceramic workpieces. The ground surface was evaluated using Scanning Electron Microscopy (SEM). As a result it can be said that the mechanism of material removal in the grinding of ceramic is largely one of brittle fracture. The increase of the hmax can reduce the tangential force required by the process. Although, it results in an increase in the surface damage, reducing the mechanical properties of the ground component.

Resistência mecânica de juntas coladas em madeira de Eucalyptus sp

De Conti, Andrea Cressoni
Fonte: Universidade Estadual Paulista (UNESP) Publicador: Universidade Estadual Paulista (UNESP)
Tipo: Tese de Doutorado Formato: 103 f. : il.
POR
Relevância na Pesquisa
45.81%
Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES); Pós-graduação em Engenharia Mecânica - FEG; O presente trabalho teve como objetivo principal, verificar o desempenho de juntas coladas de peças de Eucalyptus sp., submetidos à esforços de cisalhamento e à tração normal, em função da qualidade superficial dos planos da madeira colados e das superfícies usinadas em relação à posição dos anéis de crescimento da madeira, empregando-se dois adesivos de diferentes fabricantes, à base de Poli Acetato de Vinila (cola PVA). Os adesivos foram denominados por C1 e C2, sendo que o primeiro apresentava certa resistência à umidade enquanto que o segundo não. Na usinagem das superfícies da linha de colagem dos corpos de prova, foram empregadas as velocidades nominais de avanço „„ ” para o processo de fresamento: 6,0 m/min; 11,0 m/min e 15,0 m/min, correspondendo, respectivamente aos avanços por dente “fz” da ferramenta de corte: 0,86 mm; 1,57 mm e 2,14 mm. Os corpos de prova confeccionados foram preparados para composições com linha de cola em diferentes planos em relação aos anéis de crescimento da madeira. Tais composições de planos resultaram nos seguintes conjuntos de superfícies coladas: R-R; R-T; T-T e RT-RT...

Alterações nas caracteristicas da superficie de compositos restauradores sumetidas a diferentes tecnicas de acabamento e polimento; Changes in surface characteristics of restorative composites subjected to different techniques for finishing and polishing

Vera Lucia Schmitt
Fonte: Biblioteca Digital da Unicamp Publicador: Biblioteca Digital da Unicamp
Tipo: Tese de Doutorado Formato: application/pdf
Publicado em 22/04/2010 PT
Relevância na Pesquisa
45.88%
Inúmeras alterações foram feitas na fabricação das resinas compostas fotoativáveis, especialmente na tentativa de obter melhor estabilidade de cor, adequada resistência ao desgaste e lisura de superfície clinicamente aceitável. Neste contexto, fabricantes têm, promovido alterações no tamanho das partículas de carga e incorporado a maior quantidade de componentes inorgânicos no interior da matriz resinosa. Além da composição do material, os procedimentos de acabamento e polimento podem também influenciar na qualidade superficial da resina composta, relacionando-se diretamente com rugosidade. Superfícies rugosas predispõem a restauração a maior retenção de biofilme bacteriano, facilitando o desenvolvimento de lesões cariosas, manchamentos além de interferir no seu brilho e estética finais. Neste contexto, esta tese propôs a avaliar qualitativamente a topografia de superfície de resinas compostas microhíbridas e nanoparticuladas, em função de diferentes combinações entre técnicas de polimento e resinas compostas. Com objetivo didático, esta tese foi dividida em 3 partes, como descrito a seguir. Parte 1: avaliar a influência que diferentes técnicas de acabamento e polimento exercem sobre a rugosidade da superfície de uma resina composta nanoparticulada. Parte 2: comparar a estabilidade de cor e a característica de superfície promovida por técnicas de acabamento e polimento que empregam um ou múltiplos passos sobre resinas microhíbridas e nanoparticuladas...

Optimum sterilization: a comparative study between average and surface quality

Silva, C.L.M. ,; Oliveira, F.A.R; Pereira, P.A.M; Hendrickx, M.
Fonte: Wiley Blackwell Publicador: Wiley Blackwell
Tipo: Artigo de Revista Científica
Publicado em //1994 ENG
Relevância na Pesquisa
45.99%
Sterilization temperatures to maximize volume average or surface quality retention were calculated for one-dimensional conduction heating foods as a function of (1) Food Properties, (2) Processing Conditions and (3) Processing Criteria. A target lethality at the least-lethality point was used as a constraint, and optimal temperatures were qualitatively and quantitatively compared for equal design variables. Average quality optimum conditions depend linearly on the inverse square of the Drefq-value for the quality factor. These conditions do not vary linearly with all the other influential variables, opposite to what had been observed for surface quality. Optimum temperature for maximum average quality is always higher than the corresponding one for surface quality, but the difference is not constant. A systematic approach to the dependence of average quality optimal conditions on all the relevant parameters was carried out and quantitative relations were obtained. Optimum average quality retention is independent of surface heat transfer resistance.

Quality optimization of conduction heating foods sterilized in different packages

Silva, Cristina L.M.; Oliveira, Fernanda A.R.; Hendrickx, Marc
Fonte: Wiley Blackwell Publicador: Wiley Blackwell
Tipo: Artigo de Revista Científica
Publicado em //1994 ENG
Relevância na Pesquisa
45.87%
Heat transfer during the sterilization of conduction heating foods packaged in cylindrical, retort pouch and rectangular containers, was modelled using a finite difference numerical method. Finite surface heat transfer coefficients were considered. Optimal temperatures, defined as the processing conditions that maximize surface or volume average quality retention with the constraint of a target sterility value at the coldest point, were calculated for several types of container. Optimal conditions for several case studies were compared with temperatures estimated by generalized formulae available in literature for the prediction of optimal temperatures as a function of all relevant variables. For all case studies, optimal temperatures predicted in both ways were very similar, with deviations often below ± 1°C. For most packages, the simple-to-use generalized equations, developed for one-dimensional geometries, can therefore be used instead of lengthy numerical calculations involving two- and three-dimensional geometries.

Advanced ceramics: evaluation of the mechanism of stock removal and ground surface quality

Bianchi,Eduardo Carlos; Silva,Eraldo Jannone da; Silva Júnior,Carlos Elias da; Aguiar,Paulo Roberto de; Valarelli,Ivan De Domenico; Monici,Rodrigo Daun
Fonte: The Brazilian Society of Mechanical Sciences Publicador: The Brazilian Society of Mechanical Sciences
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/01/2001 EN
Relevância na Pesquisa
45.85%
The aim of this work is to evaluate the mechanism of stock removal and the ground surface quality of advanced ceramics machined by a surface grinding process using diamond grinding wheels. The analysis of the grinding performance was done regarding the cutting surface wear behavior of the grinding wheel for ceramic workpieces. The ground surface was evaluated using Scanning Electron Microscopy (SEM). As a result it can be said that the mechanism of material removal in the grinding of ceramic is largely one of brittle fracture. The increase of the h max can reduce the tangential force required by the process. Although, it results in an increase in the surface damage, reducing the mechanical properties of the ground component.

Modelling and optimization of the surface roughness in the dry turning of the cold rolled alloyed steel using regression analysis

Tanikić,Dejan; Marinković,Velibor
Fonte: Associação Brasileira de Engenharia e Ciências Mecânicas - ABCM Publicador: Associação Brasileira de Engenharia e Ciências Mecânicas - ABCM
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/03/2012 EN
Relevância na Pesquisa
45.93%
Surface quality of the machined parts is one of the most important product quality indicators and one of the most frequent customer requirements. The average surface roughness (Ra) represents a measure of the surface quality, and it is mostly influenced by the following cutting parameters: the cutting speed, the feed rate, and the depth of cut. Quantifying the relationship between surface roughness and cutting parameters is a very important task. In this study regression analysis was used for modelling and optimization of the surface roughness in dry single-point turning of the alloyed steel, using coated tungsten carbide inserts. The experiment has been designed and carried out on the basis of a three-level full factorial design. The linear, the quadratic and the power (non-linear) mathematical models were selected for the analysis. Obtained results are in good accordance with the experimentally obtained data, confirming the effectiveness of regression analysis in modelling and optimization of surface roughness in the turning process. The general conclusion is that the surface roughness has a clear downward trend with the cutting speed increase and decrease in the feed rate and the depth of cut.

Evaluation of Different Disinfactants on Dimensional Accuracy and Surface Quality of Type IV Gypsum Casts Retrieved from Elastomeric Impression Materials

Pal, P K; Kamble, Suresh S; Chaurasia, Ranjitkumar Rampratap; Chaurasia, Vishwajit Rampratap; Tiwari, Samarth; Bansal, Deepak
Fonte: International Society of Preventive and Community Dentistry Publicador: International Society of Preventive and Community Dentistry
Tipo: Artigo de Revista Científica
EN
Relevância na Pesquisa
45.89%
Background: The present study was done to evaluate the dimensional stability and surface quality of Type IV gypsum casts retrieved from disinfected elastomeric impression materials. Materials and Methods: In an in vitro study contaminated impression material with known bacterial species was disinfected with disinfectants followed by culturing the swab sample to assess reduction in level of bacterial colony. Changes in surface detail reproduction of impression were assessed fallowing disinfection. Results: All the three disinfectants used in the study produced a 100% reduction in colony forming units of the test organisms. Conclusion: All the three disinfectants produced complete disinfection, and didn’t cause any deterioration in surface detail reproduction. How to cite the article: Pal PK, Kamble SS, Chaurasia RR, Chaurasia VR, Tiwari S, Bansal D. Evaluation of dimensional stability and surface quality of type IV gypsum casts retrieved from disinfected elastomeric impression materials. J Int Oral Health 2014;6(3):77-81.

Avaliação da rugosidade superficial da madeira de Eucalyptus sp submetida ao fresamento periférico; Evaluation of wood surface roughness of Eucalypt species submitted to cutterhead rotation

Fonte: UFLA - Universidade Federal de Lavras Publicador: UFLA - Universidade Federal de Lavras
Tipo: Artigo de Revista Científica Formato: text/html
PT
Relevância na Pesquisa
45.98%
This work evaluated the quality of roughness surface of 18 years-old Eucalyptus grandis, E. dunnii and E. urophylla trees wood, to produce prepared 48 furniture. For the laboratory essays samples/species were prepared in the machining treatments in milling machine of vertical axis, in the up milling direction, in seven cut speeds (3 to 22 m.min-1). In the evaluation of the surface quality of the wood samples it was used the surface profiling instrument Taylor Hobson model Surtronic 3+, using the filter 2CR, with sampling length of 0,80 Ie or ln (mm) and cut-off of 0,80 λc (mm). The results indicated that the E. urophylla wood presented the best surface quality and with the smallest values of variation coefficient; the E. grandis wood showed intermediate values and E. dunnii wood presented the worst performance, as well as the largest value of variation coefficient. It was observed, also, that the treatment effect for the three eucalyptus wood species was related with the machining speed; better in the 3-4 m.min-1 and worse in the 22 m.min-1. The surface quality of the machined wood was related to its density, with the eucalyptus species of denser wood presenting the best quality of machined surface.; Conduziu-se este trabalho, com o objetivo de avaliar a qualidade de superfície usinada da madeira de três espécies de Eucalyptus sp...

Modelling of oxide scale evolution in hot rolling and descaling

Krzyzanowski, M.; Beynon, J.; Frolish, M.; Clowe, S.
Fonte: Trans Tech Publications Ltd Publicador: Trans Tech Publications Ltd
Tipo: Artigo de Revista Científica
Publicado em //2007 EN
Relevância na Pesquisa
45.81%
Oxide scale behaviour in thermomechanical processing has been the subject of intensive research for several years that allowed developing a finite element (FE) based model to simulate a range of events of relevance to the process and the surface quality of the hot rolled product. A range of experimental techniques have also been developed, each providing a partial insight. An overview of this research is presented in the sequence of rolling and finishing with descaling. The model has been extended to provide the basis for detailed numerical investigations of the roll/stock interface behaviour during multi-pass hot rolling operations. The modelling techniques have been used for providing design criteria for AISI430 ferritic stainless steel scale failure during bending. Modelling of near surface deformation during rolling of aluminium alloys is under consideration.; Michal Krzyzanowski, John H. Beynon, Mike F. Frolish, and Samantha Clowe

Experimental analysis of the influence of drill point angle and wear on the drilling of woven CFRPs

Feito Sánchez, Norberto; Díaz Álvarez, José; Díaz Álvarez, Antonio; Cantero Guisández, José Luis; Miguélez, Henar
Fonte: MDPI AG Publicador: MDPI AG
Tipo: info:eu-repo/semantics/publishedVersion; info:eu-repo/semantics/article
Publicado em 01/01/2014 ENG
Relevância na Pesquisa
45.86%
This paper focuses on the effect of the drill geometry on the drilling of woven Carbon Fiber Reinforced Polymer composite (CFRPs). Although different geometrical effects can be considered in drilling CFRPs, the present work focuses on the influence of point angle and wear because they are the important factors influencing hole quality and machining forces. Surface quality was evaluated in terms of delamination and superficial defects. Three different point angles were tested representative of the geometries commonly used in the industry. Two wear modes were considered, being representative of the wear patterns commonly observed when drilling CFRPs: flank wear and honed cutting edge. It was found that the crossed influence of the point angle and wear were significant to the thrust force. Delamination at the hole entry and exit showed opposite trends with the change of geometry. Also, cutting parameters were checked showing the feed's dominant influence on surface damage.; This work was supported by the Ministry of Economy and Competitiveness of Spain under the project DPI2011-25999

La finitura superficiale in Fused Deposition Modeling

Giordano, Veronica
Fonte: La Sapienza Universidade de Roma Publicador: La Sapienza Universidade de Roma
Tipo: Tese de Doutorado
IT
Relevância na Pesquisa
45.81%
Fused Deposition Modelling is a proven technology for the fabrication of both aesthetic and functional prototypes. The obtainable roughness is the most limiting aspect for its application. Indeed, the prediction of surface quality is an essential tool for the diffusion of this technology, in fact at product development stage, it allows to comply with design specifications and in process planning it is useful to determine manufacturing strategies. So a bidimensional model of the micro geometrical profile has been proposed, with the introduction of the measurement angle, the model has been extended to the third dimension. Because these models are not robust enough in predicting roughness parameters for all deposition angles, in particular for near horizontal walls. The neural networks have been used to determine roughness parameters models reliable over the entire part surface. By the utilization of an evaluation function the best solution has been found.

Tool wear monitoring and hole surface quality during CFRP drilling

RAMIREZ, Christophe; POULACHON, Gérard; ROSSI, Frédéric; M'SAOUBI, Rachid
Fonte: Elsevier Publicador: Elsevier
EN
Relevância na Pesquisa
45.89%
The present investigation focuses on the evaluation of tool wear and surface integrity in the context of CFRP cutting. Series of drilling experiments were performed on CFRP plates using cemented carbide solid drills with the aim to investigate correlations between tool damage, cutting forces, temperature and hole surface quality. In particular, a new methodology has been developed to measure the drilling temperature and to assess the quality of the hole surfaces where occurred uncut fibers. As the surface roughness criterion is not relevant for such work materials, a discussion on the definition of the surface topography is proposed for CFRP work material.

Possible explanations for different surface quality in laser cutting with 1 micron and 10 microns beams

HIRANO, Koji; FABBRO, Rémy
Fonte: AIP Publicador: AIP
EN_US
Relevância na Pesquisa
45.84%
In laser cutting of thick steel sheets, quality difference is observed between cut surfaces obtained with 1 micron and 10 micron laser beams. This paper investigates physical mechanisms for this interesting and important problem of the wavelength dependence. First, striation generation process is described, based on a 3D structure of melt flow on a kerf front, which was revealed for the first time by our recent experimental observations. Two fundamental processes are suggested to explain the difference in the cut surface quality: destabilization of the melt flow in the central part of the kerf front and downward displacement of discrete melt accumulations along the side parts of the front. Then each of the processes is analyzed using a simplified analytical model. The results show that in both processes, different angular dependence of the absorptivity of the laser beam can result in the quality difference. Finally we propose use of radial polarization to improve the quality with the 1 micron wavelength.

Pre-evaluation on surface profile in turning process based on cutting parameters

LU, Chen; MA, Ning; CHEN, Zhuo; COSTES, Jean-Philippe
Fonte: SPRINGER VERLAG Publicador: SPRINGER VERLAG
EN
Relevância na Pesquisa
45.94%
Traditional online or in-process surface profile (quality) evaluation (prediction) needs to integrate cutting parameters and several in-process factors (vibration, machine dynamics, tool wear, etc) for high accuracy. However it might result in high measuring cost and complexity, and moreover, the surface profile (quality) evaluation result can only be obtained after machining process. In this paper an approach for surface profile pre-evaluation in turning process using cutting parameters and radial basis function (RBF) neural networks is presented. The aim was to only use three cutting parameters to predict surface profile before machining process for a fast pre-evaluation on surface quality under different cutting parameters. The input parameters of RBF networks are cutting speed, depth of cut, and free rate. The output parameters are FFT vector of surface profile as prediction (pre-evaluation) result. The RBF networks are trained with adaptive optimal training parameters related to cutting parameters and predict surface profile using the corresponding optimal network topology for each new cutting condition. It was found that a very good performance of surface profile prediction, in terms of agreement with experimental data, can be achieved before machining process with high accuracy...

Performance impact of honing dynamics on surface finish of precoated cylinder bores

EL MANSORI, Mohamed; GOELDEL, Benoit; SABRI, Leila
Fonte: Elsevier Publicador: Elsevier
EN
Relevância na Pesquisa
45.87%
The surface modification of engine cylinder bores with improved sliding properties is often produced by the honing process. This multi-stage process is performed using abrasive stones loaded against the bore with simultaneous rotation and oscillation. To guarantee this process robustness with acceptable dimensional accuracy and surface quality, the stone dynamic effects in continuous balanced contact with the workpiece have to studied deeply. This paper highlights these effects on honed surface textures. The stone dynamic behavior was studied at conventional regime ranged from 0,5g to 1,5g as often used in mass production. In this range, the dimensional accuracy is ensured by opposition to the surface appearance. However, higher accelerations up to 2,5g improve simultaneously the form quality (especially straightness) and reduces the cycle time. This work shows, at least, that the bore surface finish can be dynamically controlled while honing. This technology is enabled by a micro scale regeneration mechanism of abrasive stones.

Surface quality improvement of porous thin films suitable for nanoindentation

Chen, Zhangwei; Wang, Xin; Giuliani, Finn; Atkinson, Alan
Fonte: Universidade Cornell Publicador: Universidade Cornell
Tipo: Artigo de Revista Científica
Publicado em 07/02/2015
Relevância na Pesquisa
45.9%
The reliability of perovskite material LSCF to be used as cathode parts in solid oxide fuel cells also relies on its mechanical properties. Adequate surface conditions are desired when the as-sintered porous thin films are subjected to nanoindentation for mechanical property determination. In this study, extensive cracks and considerable surface roughness were found in the LSCF films after sintering at high temperatures. This would significantly scatter the nanoindentation data and result in unreliable measurements. Various attempts including the comparison of film deposition methods, drying and sintering processes, and reformulating the ink were made to improve the surface quality. Results revealed little dependence of cracking and surface roughness on deposition methods, drying or sintering processes. It was found that the critical factor for obtaining crack-free and smooth LSCF films was the ability of the ink to be self-levelling in the earlier wet state. Reproducible nanoindentation measurements were obtained for the films with improved surface quality.; Comment: 16 figures, 2 tables, journal paper published

Aplicação de microesferas de vidro para avaliação da qualidade da superfície serrada da madeira de Eucalyptus grandis

Pigozzo, Fernando Jordão
Fonte: Universidade Federal de Lavras; Programa de Pós-Graduação em Ciência e Tecnologia da Madeira; UFLA; brasil; Departamento de Ciências Florestais Publicador: Universidade Federal de Lavras; Programa de Pós-Graduação em Ciência e Tecnologia da Madeira; UFLA; brasil; Departamento de Ciências Florestais
Tipo: Dissertação
Publicado em 17/12/2015 POR
Relevância na Pesquisa
45.94%
The use of machinery and software is growing in sawmills in order to increase the sawing yield. These measures also seek to improve the quality of sawn timber, given that warping, size variation and defects in the surfaces of the sawn pieces increase losses during finishing operations. Little is discussed in the literature concerning the surface quality of lumber. This occurs due to the shortage of evaluation methods. Therefore, the main objective of this study was to evaluate the quality of the sawn surface of Eucalyptus grandis lumber, after log sorting, defect analysis of the sawn pieces and yield calculation. For this, logs were sorted into four diameter classes. We evaluated their tapers, flattening and end checks. The sawing method was planned by Maxitoras® software - Optimber, and was compared with the actual yield. The quality of the sawn timber was assessed by measuring warping and size variation, as well as evaluating their surfaces by applying glass microspheres, based on the E-965 (ASTM, 1996) method. We concluded that: i) the shape of the logs was considered acceptable, according to the usual classification methods, however, the end check values were higher than the values found in literature; ii) the warping of sawn pieces was considered of high intensity...

A Wavelet Approach to Estimate The Quality of Ground Parts

Rubio,E.; Jáuregui-Correa,J.C.
Fonte: UNAM, Centro de Ciencias Aplicadas y Desarrollo Tecnológico Publicador: UNAM, Centro de Ciencias Aplicadas y Desarrollo Tecnológico
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/02/2012 EN
Relevância na Pesquisa
45.94%
The manufacturing process of metal parts is subjected to machining instabilities that can degrade the surface finish quality and the reliability of products. Some instabilities are of transient nature and traditional inspection systems are unable to adequately estimate the grade of affectation in the finished parts. Time-frequency analyses are techniques that overcome these limitations and have recently been incorporated in special industry inspection equipment to improve the quality of the manufactured parts. Grinding is a process used to get high precision and very smooth surface in flat or cylindrical parts because of the target applications such as the automotive industry where the highest standards can be found. This paper reports a technique to estimate the quality of ground parts based on time-frequency transforms that are used to enhance the defects. This makes it easier to implement the technique for surface characterization in online pass/no-pass inspection machines. The fundamentals of the methodology are revised and the technique is applied to the identification of vibration marks in cylindrical ground rods. Results show that this approach identifies adequately imperfections of transient nature and it is able to estimate the extension and amplitude of the defects on the surface of the manufactured parts.