Papers by Rosemar da Silva
Brazilian Journals Editora eBooks, May 25, 2022
O conteúdo dos livros e seus dados em sua forma, correção e confiabilidade são de responsabilidad... more O conteúdo dos livros e seus dados em sua forma, correção e confiabilidade são de responsabilidade exclusiva dos autores. Permitido o download da obra e o compartilhamento desde que sejam atribuídos créditos aos autores, mas sem a possibilidade de alterá-la de nenhuma forma ou utilizá-la para fins comerciais.
Procceedings of the 11th Brazilian Congress on Manufacturing Engineering, 2021
Journal of Manufacturing Science and Engineering-transactions of The Asme, Nov 2, 2017
Grinding is an abrasive process mostly used in finishing operations to provide low roughness and ... more Grinding is an abrasive process mostly used in finishing operations to provide low roughness and narrow limits of form and dimensioning to the workpiece. Due to the large amount of heat generated by friction between the abrasive and the workpiece in this process, the use of large volumes of coolant is encouraged to avoid thermal damage, such as burning and hardness variation caused by subsurface damage. On the other hand, environmental impacts and human health problems caused by coolants have been a key issue toward sustainable manufacturing, mainly because of the chemistry behind them. Thus, is important to seek for strategies to reduce the volume of fluids and their risks as well as guarantee grinding efficiency. One machining strategy is the minimum quantity of lubricant (MQL) technique, which is well consolidated over the past 25 years and one that uses low volumes of fluid mixed with compressed air flow, as well as provides less waste. However, it has generally been reported that sludge formed during grinding is forced into the wheel pores, consequently clogging its pores, thereby reducing the wheel cutting potential and its performance. A possible solution for this problem is to use an auxiliary compressed air system to clean the grinding wheel surface during machining, since the MQL conventional system is not able to clean it. In this context, this work evaluated the performance of the MQL technique with an auxiliary cleaning of the grinding wheel cutting surface in relation to the conventional cooling techniques (flood cooling) during a cylindrical plunge grinding of N2711 steel. N2711 steel is widely employed in manufacturing of molds for plastic injection processes and is one of steels more susceptible to grinding burn. The following output parameters were used to assess the performance: surface roughness, roundness, microhardness, grinding power, and grinding wheel wear. The results showed that the MQL technique, in addition to the environmental and economic advantages achieved, provided superior workpiece quality, and lower power consumed compared to the flood technique. The MQL technique proved to be an alternative method compared to the conventional technique under the conditions investigated. Also, the Malkin’s model was used to predict the grinding ratio (G-ratio) based on the experimental data obtained in this work. After regression analysis, the model predicted the G-ratio from the specific material removal rate and the cutting speed with a satisfactory accuracy of approximately 92%.
Procceedings of the 11th Brazilian Congress on Manufacturing Engineering, 2021
Anais do IX Congresso Nacional de Engenharia Mecânica, 2016
Journal of The Brazilian Society of Mechanical Sciences and Engineering, Dec 4, 2019
Nickel-based Inconel 718 stands out from other materials due to its peculiar combination of prope... more Nickel-based Inconel 718 stands out from other materials due to its peculiar combination of properties such as high mechanical strength, high hardness, high chemical inertia and low thermal expansion, as well as its ability to operate at high temperatures and in cryogenic conditions. These properties make this material suitable for aeronautic applications, especially for hot structural components, such as blades and discs of aircraft engines in which a high dimensional accuracy and low surface roughness are required. Such manufacturing requirements in general can be achieved through the grinding process. However, due to low thermal conductivity of both the Inconel 718 alloy and the conventional abrasive grinding wheels, most of heat generated during machining concentrates on the workpiece-grinding wheel interface. The usual practice for the removal of heat from grinding zone is by the application of high volume of coolants, but such technique can cause injury to the operator and harm to the environment, if special care with its use and disposal is not taken, which, in turn, increases the cost of the process. Furthermore, due to the poor machinability of Inconel 718, cutting conditions need to be different from those generally employed when grinding steels and cast irons, especially the depth of cut. Within this context, this study presents an approach for determining the grindability of Inconel 718 under different coolant delivery techniques (conventional and minimum quantity lubrication-MQL) and cutting conditions. Grinding tests were also carried out on a grey cast iron material for comparison purposes. Surface roughness, microhardness and surface texture of machined surfaces were the output parameters used to access the grindability of Inconel 718. Results showed that higher values of surface roughness were recorded after grinding the Inconel 718, compared to grey cast iron, thereby indicating the lower grindability of Inconel 718. No evidence of reduction in hardness due to thermal damage was observed after grinding both materials under the established cutting conditions.
The International Journal of Advanced Manufacturing Technology, Jan 3, 2018
Grinding is generally the first choice to provide combination of both superior surface finish and... more Grinding is generally the first choice to provide combination of both superior surface finish and closer dimensional tolerances in a machined component. This process can be employed in manufacturing of continuous and interrupted surfaces. Crankshafts and engine piston rings are examples of ground precision mechanical components having interrupted surfaces. However, the specific literature about grinding of interrupted surfaces is still scarce. In this context, aiming to further contribute to the understanding of the behavior of surface integrity of interrupted surfaces during grinding, this paper presents an experimental investigation of interrupted surfaces ground with white aluminum oxide grinding wheel. Discs of AISI 4340 hardened steel with different number of grooves (2, 6, and 12) on the external surface were tested. Experiments with discs without interrupted surface were also carried out for comparisons. In addition to the number of grooves, three values of infeed rate (0.25, 0.50, and 0.75 mm/min) were used as input parameters. The output parameters investigated were the geometric errors (surface roughness and roundness) of the workpiece material as well as the diametric wheel wear. Analysis of variance (ANOVA) test was performed to verify any statistical difference among the output variables. Results showed that both surface finish and roundness of workpieces with interrupted surfaces were higher than those obtained for continuous surface. These parameters also increased with infeed rate up to 0.50 mm/min, whereas the grinding wheel wear was more sensitive to number of grooves and infeed rate. No thermal damages were observed on the machined workpieces under the conditions investigated.
Procceedings of the 11th Brazilian Congress on Manufacturing Engineering, 2021
The International Journal of Advanced Manufacturing Technology, 2019
This paper discusses the correlations between the electromechanical impedance (EMI) technique and... more This paper discusses the correlations between the electromechanical impedance (EMI) technique and grinding parameters. The EMI technique applied in grinding is novel and has the advantage of employing cheaper equipment and requiring a simpler monitoring system when compared to traditional techniques, such as acoustic emission. Experimental tests were conducted in a controlled environment to isolate the variables of interest, and real and imaginary parts of the impedance were investigated for several frequency bands. Strong correlations among EMI and equivalent chip thickness, roughness, and microhardness of the workpiece, as well as power signals, were found. The RMSD (rootmean-square deviation) index for the real part of the signature in the band 80-85 kHz showed good correlation with roughness and power, while the CCDM (correlation coefficient deviation metric) index for the imaginary part of 50-55 kHz showed good correlation with microhardness. Those correlations allow the user to infer information about the grinding process through indirect monitoring. Keywords Grinding. Electromechanical impedance. Piezoelectric transducer. Structural health monitoring. Surface quality Nomenclature (a e) Depth of cut, μm CCDM Correlation coefficient deviation metric h eq Equivalent chip thickness, μm Q' w Specific material removal rate, mm 3 /mm.s ρ Pearson correlation coefficient R a Arithmetic average roughness, μm RMSD Root-mean-square deviation v s Cutting speed, m/s v w Workpiece speed, m/min Z 1
Proceedings of the XI Congresso Nacional de Engenharia Mecânica - CONEM 2022
CRC Press eBooks, Jul 18, 2023
Procceedings of the 11th Brazilian Congress on Manufacturing Engineering, 2021
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Papers by Rosemar da Silva