Lean six sigma como estratégia para o aumento de eficiência em laminação de alumínio

This study aims to assess the implementation of Lean Six Sigma in the preparation of plates and hot lamination process for a company of aluminum rolled products, to improve the quality, productivity and process efficiency. As a basis for achieving these goals, the DMAIC methodology and various quality tools such as Cause Effect Diagram, Process Flow, SIPOC, Pareto, FMEA and Control Chart were used, trying to propose improvements to processes and increase their efficiency. The results were significant and were the basis for the continuation of a continuous improvement project throughout the factory

Estudo do envelhecimento da liga AA 7075 encruada

Aluminum alloys are widely used in industry, because they combine different mechanical properties according to the alloying elements used in addition to thermal and mechanical treatments performed, resulting in materials with good weight/resistance relation. The 7XXX series alloys are worked heat treatable alloys commonly used in the aerospace industry, especially due to their high mechanical properties obtained after aging heat treatment, which increases the interest around 7075 alloy. Some studies with alloys which can be aged show that it is possible that cold word processes affect the results of aging. Thus, this study was intended to verify the influence of the aging process of AA 7075 alloy. There were three routes of aging with specimens previously treated thermally. In the first route T6 treatment was performed with a annealed specimen and other in solid solution. The second was the natural aging in a annealed specimen. In the last route was done aging by steps with a annealed specimen and other in solid solution with the intention to reduce the effects of natural aging. The results show that the routes 1 and 3 had similar hardness for all the samples, showing that the validity of Route 3 as an alternative and also the hardening did not affect the hardness at the end of the process, significantly reducing the time required for the highest hardness. Finally, natural aging was less effective in increasing hardness

Tratamento de modificação de eutético da liga AA356

Alloy Al-7%Si-0,3Mg (AA356), having an excellent combination of properties such as low solidification shrinkage and good fluidity, good weldability, high wear resistance, high strength to weight particularly in the automotive and aerospace engineering. The refinement of the structure aluminum silicon eutectic alloy is a fairly common practice in the casting, through the treatment knows as modification. You can get the modification for the addition of chemicals and rare earths, these have the ability to modify the structure of the eutectic, but only sodium and strontium produce a strong action modifier when used in low concentrations. The modifying effect of silicon grain turns into a fibrous form branched and enveloped by the metal matrix in the form of a composite structure that has the highest limit of tensile strength, ductility and machinability. This work will be obtained AA356 alloy ingots using two different types of molds: metal mold and sand mold. Macrographs will be made in ingots obtained for observation of the macrostructures obtained in both types of ingots. Will be sampled at strategic locations of the ingots to correlate microstructure and cooling rate. The results showed that the material of the ingot has a strong influence on the resulting micro-andmacrostructure

Estudo da propagação de trinca por fadiga sob carregamento de amplitude variável

For engineering projects that require high reliability levels, is often not enough know only physical and chemical material properties. It’s necessary understand the failure mode of these materials in operation to ensure security level in the project and establish more stringent criteria in the analysis of structural integrity. Due to this need, aircraft industry has been using aluminum alloys in their designs and projects. “Currently more than 70% of aircraft structures are built of high strength aluminum alloys among which stand out 7075-T6 and 2024-T3 alloys, which are considered basics for being used in the new alloys development.” (PASTOUKHOV & VOORWALD, 1995). Some years ago ALCOA develops Al 2524 alloy that has emerged as refinement of Al 2024 (Al, Cu. Mg) alloy, with purpose of improve fracture toughness and fatigue resistance on structural components. The present research addresses testing of fatigue crack propagation under variable amplitude loading for Al 2024 alloy, observing the interaction effects from application of overhead blocks and plastic zone at the crack tip and makes an analysis of fracture surface images

Estudo da usinagem por torneamento de ligas de alumínio

The non-ferrous materials have got so many mechanical, physical and chemical advantageous properties so that is provided to them consolidated position in industry. In this context, aluminium alloys have been seen a lot on many applications of engineering areas – specially on automotive, aeronautical and aerospace due to their main properties such as low density, high corrosion resistance, favorable structure weight / material resistance relation, among others characteristics that are mencioned through this study. This study aims to analyze the aluminium alloys behavior on a general context when they are used on turning process, taking for examples the 6262 and 7050 aluminium alloys. In this way, the analysis studies the datas obtained during the turning tests realized on 3 steps each one; those datas are concerning the medium and total rugosities – obtained with the assistance of a portable Surface Roughness Finish Tester, as well as the chips obtained during the tests - visual analysis, and the cutting tools wear – with the assistance of an optical microscope, under different conditions of application of cutting fluids (dry machining, application of coolant in abundance and MQL – Minimum Quantity of Lubricant). The results concerning this study show detailed information about influence of cutting fluids on the machining by turning of the aluminium alloys related on this work and also about aluminium alloys in general when they are used on turning processes with different conditions from one another. By this way, it was evident the MQL technique is the best one for the 6262 alloy. However, for 7050 alloy, it was evident that the dry machining is responsible for the best results

Desenvolvimento de um protetor lateral em alumínio

In view of the need to develop a device for security and lateral protection, due to the Resolution 323/09 of CONTRAN, which requires the use of such equipment for most trucks and tow trucks, the objective of this work is to develop a project for an aluminum lateral protection device, according to the ABNT NBR 14.148 regulation, that, among many specifications, stipulates that the equipment must support a load of 5 kN and suffer a maximum deflection of 30mm, but does not say what material it should be made of. The reason for choosing aluminum is because of its low density, so as not to significantly increase the curb weight of the truck, which, consequently, reduces CO2 emissions and maintenance expenses. Additionally, this material presents a good resistance/weight ratio, high resistance to corrosion, excellent surface finish and it's fully recyclable; reason why it has been gaining the attention of many industry segments. For the realization of the project, profiles were chosen to make the assembly of the set, and then a finite elements analysis was performed in the HyperWorks software, to verify if the designed device would support the loads stipulated by the regulation. One details to note is that these simulation programs could show inaccuracies, because of the size and shape of the elements that compose the mesh, and for many other reasons, so it is necessary that, even with the results coming back satisfactory, actual physical tests are conducted to validate the proper functioning of the equipment, which was not done for this study

Efeito do fornecimento de diferentes níveis de alumínio dietético na qualidade óssea de codornas poedeiras (Coturnix japonica)

O alumínio está presente de forma marcante em nosso cotidiano, com várias possibilidades de contaminação para o ser humano e animais, através da ingestão de alimentos ou aditivos presentes nos alimentos ou, também, através do uso de medicamentos. Por apresentar uma forte carga elétrica, um forte poder de polarização e características similares com elementos da hidroxiapatita, o alumínio age como um competidor de nutrientes na matriz óssea, Por isso, ele pode ser causa danos à saúde dos seres vivos, como a osteoporose. Diante disso, a presente pesquisa teve como objetivos estudar a influência de diferentes níveis de alumínio na dieta de codornas poedeiras, sobre as características físicas e químicas de seus ossos. A densidade e a porosidade óssea foram determinadas pelo método de imersão em água, utilizando o princípio de Arquimedes. Os resultados obtidos mostraram que concetrações até 20 mg de alumínio por kg de ração fornecida causa uma diminuição na densidade óssea e volta a aumentar para concetrações maiores que este limiar. A porosidade óssea, segue o inverso da densidade. Ela aumenta com concetrações até 20 mg de alumínio por kg de ração fornecida e volta a diminuir para concetrações menores

Analise do sistema de medição em peças aeronaúticas através do estudo de R&R (repetibilidade e reprodutibilidade)

The Measurement System Analysis (MSA - Measurement System Analysis) is a statistical methodology developed to study and analyze the behavior of the measurement systems, and, therefore, allow the increased of the confidence readings performed by measuring instruments. It’s widely used in the automotive industry since the 90’s and is a mandatory requirement for the approval of the parts according to ISO Standard of the automotive sector. However, the aerospace industry doesn’t require this type of Study, once which the vast majority of aeronautics parts have characteristics (dimensions) with very tight tolerances, closed, ie, at the home of microns. This work aims to create lists of recommendations for definitions of measuring instruments in developing of control plans, which correlates tolerances fields of characteristics for different settings and acceptance of the instrument, classified as optimum, recommended and not recommended, through of the study of R&R (Repeatability and Reproducibility) in aeronautics parts. Every methodology of the experimental part was based on modern strategy of continuous improvement, the DMAIC (Define Measure Analyze Implant Control), in order to achieve better measurement method used in the control of milling aeronautics parts, identifying and reducing the variations of the measurement process. The results of the R&R Study in large part of measuring instrument manuals were considered acceptable and/or recommended, ie with values of %P/T and %RR lower than 30%, providing statistical data which have enabled the elaboration of tables of recommendations, which, from this work, have turned into very important documents and aid for Process Engineering, having in their hands a technical study able to identify which is the most appropriate instrument to get a more robust dimensional... (Complete abstract click electronic access below)

Processo de fabricação de tarugos pelo método HotTop de ligas de alumínio da série 6XXX e as não conformidades desse processamento

The goal of this work is to report some problems that occur in the in the production of aluminum billets (series 6XXX) produced by the hot top process in the Alcoa aluminum Inc. The aluminum fabrication process is described from its first stage, since the mining until the reduction, smelting and treatment of the metal. One of the plant’s final product, are billets for clients that produce profiles by extrusion. The product’s final quality highly depends on the whole production process. Therefore it’s necessary to use good practices in the treatment of the metal, follow up its fabrication and control its thermal treatment, in order to meet the required standards to satisfy the clients. The billet’s production method and its variables will be detailed through temperature and casting speed, cone of water flow, cooling rate, duration of thermal treatment, degassing and metal “in line “filtering, in other words when it’s still found in its liquid state. The non-conformities of the process were studied by metallographic analysis, both macrostutural and microstructural that will be described and discussed in this work

Níveis nutricionais como fatores de crescimento de Styrax pohlii em cultivo hidropônico

O sucesso de uma espécie em um hábitat é dependente de seu desempenho ecofisiológico, que pode ser definido com variáveis de crescimento, que, por sua vez, pode relacionar-se aos recursos naturais disponíveis. Um dos fatores determinantes da ocorrência de espécies é o fator edáfico. A baixa fertilidade do solo das fisionomias do Cerrado são semelhantes, mostrando altos teores de alumínio (Al3+) e baixo pH. Contudo, solos de matas de brejo, onde Styrax pohlii é freqüente, apresentam teores levemente maiores de matéria orgânica. Logo, é possível que esta maior fertilidade do solo possa influenciar o crescimento de S. pohlii, podendo explicar sua maior ocorrência nestes hábitats. Objetivou-se medir a biomassa de órgãos, área foliar, número de folhas, área foliar específica, razão de massa de folhas e a razão de área foliar de plantas de S. pohlii, submetidas a diferentes cargas de nutrientes em cultivo hidropônico. Testou-se a hipótese de que diferentes cargas de nutrientes (100%, 50%, 25%, 10% e 1% da concentração total de uma solução nutritiva) alteram as variáveis de crescimento da espécie. As plantas foram cultivadas em caixas plásticas (20 L), contendo as diferentes cargas de nutrientes, em solução nutritiva com alumínio (Al3+) e pH 4,0. Utilizaram-se 20 parcelas (caixas plásticas) com cinco repetições (plantas) por parcela, perfazendo um total de 100 plantas. Realizaram-se quatro coletas (a cada 30 dias), onde as variáveis foram medidas. Os resultados mostraram que a espécie não respondeu a incrementos de nutrientes na solução nutritiva, podendo ela ser considerada não plástica a fatores edáficos. Considerando a grande ocorrência de indivíduos de S. pohlii em matas ripárias, ciliares e de brejo, os resultados sugerem que a fertilidade levemente maior nesses ambientes, dada pela elevação da matéria orgânica, não explica totalmente sua maior ocorrência nessas vegetações

Efeitos fotocrômico e termocrômico em ormosils dopados com azobenzenos

The sol-gel process and the wide variety of alkoxides commercially available have facilitated the processing of various Organic-Inorganic Hybrid Materials. In general, the hybrids are excellents matrix to incorporate organic or inorganic dopants that presents photochromic, thermochromic, and halochromic effects and in some cases photorefractive effects. The GPTS-TEOS hybrid matrix when deposited in the form of film is very resistant, adherent, has excellent transparency in visible region and allows to be doped with various azo-dye and metal salts of unusual oxidation states. One of the main characteristics of the azo-dyes when immersed in some hybrid matrix , is the capacity to isomerizes through group Azo (-N = N-) would can be commutated between the Cis (Z) and Trans (E) configurations by means of light or heat. Our goal was through the sol-gel process to prepare hybrid films of GPTS-TEOS doped with azo-dyes Methyl Red and Disperse Red 1, and characterize them optically. The characterizations are performed using techniques of UV / Vis spectroscopy, to identify changes in the absorption band of azo-dyes in the presence of optical pumping, (photochromic effects), in function of temperature (thermochromic effect). These properties are of wide scientific and technological interest because they will contribute to the confection Smart Windows (windows sensible to light), temperature sensors monitored optically and also in the recording of amplitude and phase diffraction gratings

Análise da curva de resfriamento e refino de grão da liga de alumínio AA 356

The macrostructure of an alloy solidification in the raw state is of utmost importance due to its influence on mechanical properties. A structure showing columnar grains is generally undesirable in most applications of cast products and grain refining aims to suppress the formation of these grains and get a fine-grained equiaxed structure that improves the supply of liquid metal and the mechanical properties, as yield strength and tensile strength limit, as well as the tendency of formation of hot cracks. The type and size of grains formed are determined by chemical composition, cooling rate and the use of inoculum for grain refining. Titanium and boron are the major refiners in the aluminum industry and can be added to the molten metal in the form of alloys such as Al-Ti, Al-Ti-B or Al-B. In this paper we will discuss the information obtained from cooling curves and first derivative of the cooling curve to obtain the thermal parameters that influence the process of grain refining alloy AA 356.0

Remoção de matéria orgânica e nitrogênio de efluentes provenientes de abatedouros de bovinos por meio de reator aeróbio operando em bateladas sequenciais com adição de coagulante químico

The volume of liquid effluent generated in cattle slaughterhouses is quite high and cannot be released untreated in water bodies due to its high pollution load of predominantly organic origin. To minimize the environmental impacts of its industrial wastewater and meet the local environmental legislation, abattoirs shall make the treatment of these effluents. The present work aims to develop the study of a reactor by sequential batch pilot scale, in order to optimize their performance in treating wastewater from a cattle slaughterhouse. The treatment system used was developed and installed in the Laboratory of Wastewater Treatment, in Faculty of Science and Technology UNESP, Presidente Prudente campus. The procedure used followed the operation of sequential batch reactors, in which all processes and treatment operations occurring sequentially in a single unit, by establishing specific operating cycles, which comprise the following separated phases: aerobic reaction, anoxic reaction, sedimentation and emptying. Aiming to improve the quality of treatment was planned the addition of coagulant Poly Aluminum Chloride (PAC) in the reactor, by determining their optimal dosage by Jar-test trials. Were prepared four steps with specific operating cycles: step one or acclimatization (10 hour of aeration, one hour and 30 minutes of sedimentation and 30 minutes for exchanging the effluent); step 2 (6 hours of aeration or aerobic phase, 4 hours and 45 minutes of stirring or anoxic phase and 1 hour and 15 minutes for sedimentation and exchange effluent); step 3 (2 hours and 30 minutes of aeration, 8 hours and 15 minutes of stirring and 1 hour and 15 minutes for sedimentation and exchange) and step 4 (2 hours of aeration, 8 hours and 45 minutes of stirring and 1 hour and 15 minutes for sedimentation and exchange)... (Complete abstract click electronic access below)

Desenvolvimento de um sistema para caracterização de dispositivos eletroluminescentes

The materials designed to be used in electroluminescent (EL) devices construction are studied and improved since 1936. Great interests in the development of this kind of devices are mainly due to its low power consumption, flexibility, low cost and easy processing. One class of ELs devices with these characteristics are produced by employing a organic-polymeric/inorganic composite from a conductive polymer blend and an inorganic electroluminescent material (Zn2SiO4:Mn) dispersed in the polymeric matrix. This kind of device operates in d.c. or a.c. potentials, with EL of hundreds candela in the green region of the visible spectrum. However, few studies on the light emission were performed for these devices. In order to characterize devices made from composites, in this work is proposed a method of characterizing the electroluminescence associated with the impedance spectroscopy technique. To implement the technique of impedance spectroscopy was employ an experimental setup consisting of a source of a.c. voltage, an oscilloscope, and a reference resistor. Associated with this system, was use a photo diode and an analog electrometer to characterize the emitted light signal from the sample. The system was implemented allows characterization by impedance spectroscopy in the frequency range from 0.2 Hz up to 2 MHz and voltage amplitudes of 5 mV up to 20 kV. This system permits, at the same time, measurement of the RMS value of the luminance for devices in frequency range from 20 Hz up to 2 MHz. To test the system efficiency, an EL device was characterized showing analogous results to those reported in literature. By doing this, was demonstrated the efficiency of the system for electroluminescence characterization associated with the electrical characterization by impedance spectroscopy, for devices

Estudo do efeito do modificador Al-Sr no tratamento de modificação do eutético da liga AA356

The AA356 alloy is an alloy widely used in the automotive industry and aerospace due to its excellent mechanical properties. Refining the structure of eutectic silicon aluminum alloys is a fairly common practice in the foundry through treatment known as modification. This can be achieved by modifying agent adding chemicals such as contained in groups I and IIa of the periodic table and rare earths (europium, céreioi, praseodymium, neodymium, etc.). Has the ability to modify the structure of the eutectic, but only sodium and strontium produce an action modifier strong when used in low concentrations. The modifying effect of the shafts turn silicon into a fibrous form and branched surrounded by metallic matrix in the form of a composite structure that has the highest limit of tensile strength, ductility and machinability. In this work will be obtained ingots with and without the modifier type Al-10% Sr, made in sand molds and are generated and analyzed cooling curves and also the study of the macrostructure and microstructure of the solidified material. It was found that by adding the Al-Sr made shorten the solidification time and lower the grain size