Additive manufacturing techniques are known for the unrivalled geometric freedom they offer to designers. It is one of the mainstays of “metal 3D-printing”, compared to casting, which, in contrast, ...implies more restrictions because some shapes do not cool evenly or may need moulds or forms. Despite the possible presence of defects inside additive manufactured components, such as oxide films, pores or unmelted powder, they can be strongly reduced or controlled by process parameters optimization. That seems not true for a casting component, in which defects can vary a lot from zone to zone according to the solidification conditions. Porosity inducing process parameters in selective laser melted AlSi10Mg aluminium alloy are carefully analysed with the aim to find optimal conditions that guarantee the maximum material density and the best mechanical properties. Finally, a model is proposed that correlates the amount of pores with the alloy ultimate tensile strength.
The toothed chain joint is a major component in heavy lifting equipment. They are usually fabricated using casting; however, residual casting defects in the joint tend to reduce mechanical strength ...and can lead to crack formation and creep following long-term usage. They also pose a safety hazard. In this study, numerical simulation was used to optimize the investment casting parameters for toothed chain joints of SNCM220 alloy. Optimization was based on predictions of cavity shrinkage, as determined using the retained melt modulus and probabilistic defect parameter, and porosity defects, estimated using the combined defect parameter-Niyama criterion. Preliminary simulation and experiment results were used to guide the establishment of two casting schemes: CaseA (reducing the length of the runner and removing the auxiliary inlets on both sides) and CaseB (increasing the number of inlets). Further simulations were conducted wherein the runner was covered with cotton insulation (6-mm thick). Virtual thermo-dynamical sensors were also used to determine the rate and direction of solidification in the mold cavity. Under nondestructive testing based on X-ray analysis, the investment castings fabricated under optimal conditions exhibited none of the detrimental defects commonly associated with this type of casting.
Scroll compressors are popularly applied in air-conditioning systems. The conventional fabrication process causes gas and shrinkage porosity in the scroll. In this paper, the electromagnetic stirring ...(EMS)-based semisolid multicavity squeeze casting (SMSC) process is proposed for effectively manufacturing wrought aluminum alloy scrolls. Insulation temperature, squeeze pressure, and the treatment of the micromorphology and mechanical properties of the scroll were investigated experimentally. It was found that reducing the insulation temperature can decrease the grain size, increase the shape factor, and improve mechanical properties. The minimum grain size was found as 111 ± 3 μm at the insulation temperature of 595 °C. The maximum tensile strength, yield strength, and hardness were observed as 386 ± 8 MPa, 228 ± 5 MPa, and 117 ± 5 HV, respectively, at the squeeze pressure of 100 MPa. The tensile strength and hardness of the scroll could be improved, and the elongation was reduced by the T6 heat treatment. The optimal process parameters are recommended at an insulation temperature in the range of 595–600 °C and a squeeze pressure of 100 MPa. Under the optimal process parameters, scroll casting was completely filled, and there was no obvious shrinkage defect observed inside. Its microstructure is composed of fine and spherical grains.
This paper deals with the application of Six-Sigma methodology to the flywheel casting process in foundry to minimize the defects in this process. The primary tools used in this interventionist ...process were the process map, cause-and-effect matrix and the failure mode effective analysis. The present study proposes to measure the performance criteria of the process through investigating the effect of working parameters, namely, moisture content, green strength, permeability, and loss on ignition on sand preparation. The experimental results were statistically analyzed and modeled through response surface methodology (RSM). Based on the findings, the optimized process parameters were taken for experiment and better performance obtained in the production process was confirmed. The comparison between the existing process and the proposed process has been attempted in this paper and the results have been discussed in detail.
Software for modeling the casting process Kukartsev, V A; Rukosueva, A A; Ogol, A R ...
Journal of physics. Conference series,
12/2019, Letnik:
1399, Številka:
3
Journal Article
Recenzirano
Odprti dostop
The permanent improving of physical and mechanical properties of cast alloys, the improving of old processes and the introduction of new processes allowing to get a precision casting with a soft ...surface and not demanding the machining and, finally, a constant increasing of the productivity of applied processes change not just technological but economic case of the modern foundry. The computer modeling becomes an inalienable part of processes of the new model design and the engineering of technological processes for its production. It gets a status of an important and often a decisive competitive advantage. The computing of the gating system for casting of 20x5ML steel was completed and the most optimal option allowing getting castings without defects was found with LVMflow modeling program. Output of valid casting was computed, there were finding out a needed metal filling of furnace and selecting batch's material to get the necessary chemical compound of alloy. Based on condition that the smelting will be carried out on return and fresh materials, a spending of acquisition has been defined. Then the way of computing was used as an initial variant to the checking modeling with ProCAST program which allowed to obtain higher amount of valid castings due to the changing the design of gate system. It let change metal filling of furnace and pick up a need in fresh materials in the different way. The calculation of costs for acquisition is revealed that the using of ProCAST let to achieve the reducing to get casting with saving needed quality of alloy.
Semi-solid die casting process due to its advantages of compact process, high performance and low cost is widely applied in automobile, communication and other industries for the preparation with ...high performance aluminum alloy castings. Compared with liquid metal melt, the filling behavior is laminar flow for semi-solid metal melt with higher apparent viscosity. In the process of semi-solid die casting, the semi-solid metal melt from different directions came together, it will lead to "rewelding" defects if with insufficient fusion or uneven slurry state. In this paper, the formation reasons and forms of flow "rewelding" defects are analyzed. By numerical simulation and experimental analysis, the flow state of semi-solid metal melt at the junction of filling frontier is represented, and the state of "rewelding" defect is characterized. The effect of eliminating defects is analyzed by modifying the mold structure, such as redesigning overflow and venting systems at the confluence position. The results show that the microstructure of the "rewelding" defects in the confluence position of the semi-solid metal melts is the segregati12on of solid and liquid phase, gas, oxidation inclusions and other defects. Different semi-solid die casting process will affect the flow state and defect size at the location of different semi-solid metal melt coming together. By means of the process control and the mold structure optimization, "rewelding " defects can be removed from the product cavity. The aluminum alloy semi-solid die-casting products with high performance are obtained finally.
In this contribution, the Sapotech Reveal CAST machine vision-based surface inspection solution is presented in the context of assessing the surface quality of hot steel slabs during the process of ...continuous casting.
Further, a Deep Learning (DL) based approach for defect detection and classification is presented. Deep Learning enables the assessment of surface quality and the detection of defects, which is extremely challenging to be performed using classical machine vision methods. In Reveal CAST, the tools and methods for training, testing, and applying Deep Learning are integrated into a single product.
Finally, a cloud enabled Reveal CAST case for Deep Learning is presented with example results from a hybrid cloud-edge reference production system.
En el proceso de microfundición es común que las piezas fabricadas presenten defectología asociada al manejo de materiales, procedimientos y planes de control que muchas veces no están normalizados y ...que pueden afectar requisitos de calidad. El presente estudio comenzó con la selección de un grupo de cáscaras cerámicas usadas en la producción de piezas microfundidas; luego de verificar su defectología, se procedió a reprocesar y aplicar durante el transcurso de desencerado de los moldes cerámicos, diferentes valores de temperatura y presión. El objetivo del presente estudio consistió en verificar el efecto de dichas variables, analizando los defectos obtenidos en las piezas fabricadas por este proceso. Para esto, se caracterizaron ceras vírgenes y reprocesadas usadas en la fabricación de los patrones de cera, mostrando que el uso de ceras reprocesadas puede afectar la calidad de los moldes cerámicos y, por consiguiente, de las piezas obtenidas si no se tiene un plan de control para impedir su contaminación. Se determinó que existe una relación directa entre variaciones de temperatura y presión con la penetración y la fluidez de la cera usada en la obtención de piezas con menos defectos. Finalmente, las características operativas que mejor respuesta dieron en el proceso de desencerado necesario para la obtención de moldes cerámicos, fueron las relacionadas con la presión de 120 psi y temperatura de 170 °C, demostrando que dichas variables influyen en el proceso de obtención de moldes cerámicos y, por lo tanto, en la calidad de las piezas microfundidas.
In this current scenario of globalization, foundries play a key role for manufacturing industries as they are the major source of castings. Casting has various processes like Pre casting Processes, ...pattern making, core making, moulding and mould assembly making, Casting Processes, furnace charging, melting, holding and pouring, and Post casting Processes, shakeout, inspection and dispatch etc. In India there are many foundry have followed conventional and manual operations. Today’s competitive environment has, lower manufacturing cost, more productivity in less time, high quality product, defect free operation are required to follow to every foundry man. Mould shifting, Crushing, Lower Surface finish, Shrinkage, Porosity, Cold shut and Extra material are common casting defects due to these manual operations. These defects directly affect on productivity, profitability and quality level of organization.
In this paper all data presented is taken from one foundry. As a key industry a foundry’s performance should be effectively high in terms of production with minimum number of rejections. Castings are the major inputs for most industrial products hence foundry industry is most indispensable. Casting is an integrated process considered as an artwork with experienced professionals for high quality yield, even then in highly controlled environment defects are dominant to take place leading to rejections, contrary to rejections a foundry’s key attempt is to satisfy the demands neglecting quality levels. The challenges of casting defects are to be identified and minimized for effective castings. This study provides an intense knowledge of critical casting defects and their root cause analysis. In this paper efforts are made to achieve technically feasible remedies for minimizing several casting defects and improving the quality of castings which will serve as control measures for quality control professionals with zero defect concepts.
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