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José M. Torralba - One of the best experts on this subject based on the ideXlab platform.
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Capillary rheology studies of INVAR 36 feedstocks for Powder Injection moulding
Powder Technology, 2015Co-Authors: Julia Hidalgo, Antonia Jiménez-morales, Thierry Barriere, Jean-claude Gelin, José M. TorralbaAbstract:Capillary rheology was used to determine the shear viscosities of low expansion alloy INVAR 36 feedstocks for Powder Injection moulding (PIM) based on gas atomized Powders and cellulose acetate butyrate (CAB) and poly-ethylene glycol (PEG) binders. Different variables that describe the flow behaviour were analysed, in particular, the relationships between viscosity of the melted feedstock with different conditions, such as shear rate (. γ˙), temperature (T), solid loading (Φ) and particle size (PS). The viscous behaviour was physically interpreted and discussed, and a generalised rheological model was proposed that involves all of the dependant parameters: γ˙, T, Φ and PS. The particular rheological behaviour of the feedstocks, which deviates from typical pseudoplastic behaviour, has a relevant correlation with the proposed model. Moreover, the model can be used when similar behaviours are observed in other systems.
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optimisation of eco friendly binary binder system for Powder Injection moulding
Powder Metallurgy, 2014Co-Authors: C Abajo, Javier Ruiz Hidalgo, A Jimenezmorales, José M. TorralbaAbstract:In recent years, many efforts have been made to obtain more environmentally acceptable Powder Injection moulding processes. In this sense, the purpose of this study is to optimise an eco-binder based on polyethylene glycol (PEG) as a water soluble component and cellulose acetate butyrate (CAB) as a natural backbone polymer derived from cellulose for Powder Injection moulding of zirconium silicate Powders until a solvent debinding stage. Four different feedstocks have been investigated. As well as, a volume fraction of PEG and CAB 70/30 (vol.-%) and a solid loading of 57·5 (vol.-%) were maintained, molecular weights of polymers were combined in order to minimize distortion during binder solvent extraction. Water solvent debinding was carried out at three temperatures stepwise during 5 h. As a result, efficient removal of the PEG as well as free defects samples were obtained after solvent debinding for binder systems based on low molecular weight of PEG.
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thermal stability and degradation kinetics of feedstocks for Powder Injection moulding a new way to determine optimal solid loading
Polymer Degradation and Stability, 2013Co-Authors: Javier Ruiz Hidalgo, A Jimenezmorales, José M. TorralbaAbstract:Abstract Degradation kinetics and the thermal stability of zircon Powder Injection moulding feedstocks (PIM) based on cellulose acetate butyrate (CAB) and polyethylene glycol (PEG) binders were investigated using simultaneous thermogravimetric analysis (STA). The initial decomposition temperature (IDT) and the integral procedure decomposition temperature (IPDT) were used to analyse the thermal stability of the binder system as a function of the solid loading content. The degradation kinetics was studied, and the degradation activation energy was assessed for varying zircon Powder contents using isoconversional methods. All the methodologies revealed changes in the thermal degradation behaviours of the feedstocks for solid loadings that were previously determined to correspond to optimal solid loadings using other experimental procedures. These results may promote the proposal of thermodynamic degradation studies of feedstocks as an alternative or complementary technique to determine optimal solid loading contents in Powder Injection moulding (PIM). The studies in this paper also examined PIM process operation temperatures for zircon feedstocks.
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Powder Injection moulding processing of small parts of complex shape
International Journal of Microstructure and Materials Properties, 2013Co-Authors: José M. Torralba, Javier Ruiz Hidalgo, A JimenezmoralesAbstract:Powder Injection Moulding (PIM), Metal Injection Moulding (MIM) when is limited to metals, is a fabrication route of parts with the final shape desired. This process combines the high capability of polymer Injection moulding to produce complex shapes with the advantages of a Powder route to process metallic, ceramic or composites materials. The process has some limitations that comes from different technological steps involved in the production of the part (feedstock production, Injection, debinding and sintering). All of these different steps can be industrially controlled, being the PIM process a real alternative to produce complex parts in a high rate production method that can compete with many other processing methods to produce materials. In this work, we will go through the different steps of this manufacturing process, making special emphasis on the solutions provided by the Powder technology group of the University Carlos III of Madrid (UC3M).
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torque rheology of zircon feedstocks for Powder Injection moulding
Journal of The European Ceramic Society, 2012Co-Authors: Javier Ruiz Hidalgo, A Jimenezmorales, José M. TorralbaAbstract:Abstract In this work, a cellulose acetate butyrate (CAB) and polyethylene glycol (PEG) blend is used as the binder system in a zirconium silicate mineral Powder feedstock for Powder Injection moulding. These irregular zircon Powders make the mixing process and the selection of an optimal solid loading level a difficult task. Torque rheology methodologies combined with other techniques are used for evaluation of the parameters affecting the mixing process and determination of the critical Powder volume concentration (CPVC). Temperature variations during the mixing process are monitored and used as an indicator of the friction energy of the system and thus for the optimal solid loading selection. There have thus far been limited amounts of work conducted on torque rheology of highly loaded feedstocks that incorporate a study of the system's temperature evolution. A detailed study could be a key factor for understanding the mixing behaviour of highly loaded feedstocks.
Shu Beng Tor - One of the best experts on this subject based on the ideXlab platform.
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mixing and characterisation of 316l stainless steel feedstock for micro Powder Injection molding
Materials Characterization, 2005Co-Authors: L Liu, Ngiap Hiang Loh, Shu Beng Tor, B Y Tay, Y Murakoshi, R MaedaAbstract:Abstract In recent years, micro Powder Injection molding (μPIM) is being explored as an economical fabrication method for microcomponents. μPIM, adapted from Powder Injection molding (PIM), has the same four main processing steps as PIM: mixing of Powder and binder system to form the feedstock, Injection molding, debinding and sintering. Unlike PIM, the feedstock for μPIM requires more stringent characteristics. Thus, commercial feedstock may not be suitable especially for microstructures with high aspect ratio. In this paper, the mixing, characterisation and feasibility of an in-house feedstock for the Injection molding of microstructures, each of ϕ100 μm×height 200 μm, is reported. The feedstock comprises 316L stainless steel and a multi-component binder system. The effects of Powder loading and extrusion on mixing and feedstock homogeneity were investigated. The rheological and thermal characteristics of the feedstock were determined and used in subsequent processing steps. The results show that the feedstock can be used for the fabrication of the microstructures with good shape retention.
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replication of metal microstructures by micro Powder Injection molding
Materials & Design, 2004Co-Authors: N H Loh, Yutaka Murakoshi, Shu Beng Tor, R MaedaAbstract:Abstract In this paper, a study on the production of 316L stainless steel microstructures by μPIM (Powder Injection molding) is presented. Two types of mold inserts were used and the molding was conducted on a conventional Injection molding machine. Based on the characteristics of the mold inserts and the feedstock, suitable processing parameters were selected. Some requirements for the production of the microstructures are discussed. For example, a relatively high mold temperature, high Injection pressure and holding pressure were required. The study showed that 316L stainless steel microstructures of φ100 × 200 μm can be Injection molded, but there were incomplete filling and demolding problem in the case of smaller microstructures of φ60 × 191 μm. The molded parts were successfully debound and sintered.
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Characterization of Powder Injection molding feedstock
Materials Characterization, 2002Co-Authors: Zhen Liu, Ngiap Hiang Loh, Shu Beng Tor, Khiam Aik KhorAbstract:Abstract Powder Injection molding (PIM) is a cost-effective technique for producing small, complex, precision parts in high volumes. PIM consists of four main processing steps: mixing, Injection molding, debinding and sintering. To reduce the design-to-manufacture cycle time for Injection molding, simulation software could be used. To have a good understanding of the PIM process and to provide the necessary data for simulation, characterization of the material is essential. This paper presents the characterization of PIM feedstock consisting of 91 wt.% M2 high speed steel (HSS) Powder and 9 wt.% PAN250 polymer binder. The mechanical properties (Young's modulus, Poisson's ratio, in-plane shear modulus), thermal properties (coefficient of thermal expansion (CTE), softening point, transition temperature, specific heat, thermal conductivity) and rheological property of the feedstock were established. The CTE of the molded feedstock in three perpendicular directions differed significantly. Except for the specific heat, the mechanical and thermal results showed that the feedstock's properties were generally closer to a polymer rather than a metal. Rheological results exhibited pseudoplastic or shear thinning flow behavior, where its viscosity decreased with increasing shear rate. The feedstock viscosity also decreased with increasing temperature and was found to be suitable for molding.
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production of metal matrix composite part by Powder Injection molding
Journal of Materials Processing Technology, 2001Co-Authors: N H Loh, Shu Beng Tor, Khiam Aik KhorAbstract:Abstract The application of Powder Injection molding (PIM) to metal matrix composites (MMCs) comprising of 316L stainless steel and TiC Powders are presented. The processing steps are discussed and a suitable set of Powder loading, mixing procedure, molding condition and debinding schedule was established. Defect-free parts were successfully produced. The effects of sintering parameters on the microhardness and density were studied. The addition of TiC improves the microhardness and density. Increasing the sintering temperature or heating rate also improve the above-mentioned properties.
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Mixing and characterization of feedstock for Powder Injection molding
Materials Letters, 2000Co-Authors: R Supati, Ngiap Hiang Loh, Khiam Aik Khor, Shu Beng TorAbstract:Abstract Feedstock preparation for Powder Injection Molding (PIM) is a very crucial step since deficiencies in quality of the feedstock cannot be corrected by subsequent processing adjustments. Hence, it is important that the feedstock is homogeneous and free of Powder–binder separation or particle segregation. The quality of the feedstock in the mixing process depends on numerous parameters such as mixing time, mixing temperature, sequence of material addition, Powder size and shape, formulation of binder, shear rate, and Powder loading. The present mixing study was conducted with 316L stainless steel and titanium carbide Powders. The main objective was to establish suitable mixing parameters such as Powder loading, mixing speed and mixing temperature. The rheological characteristics of the feedstocks, under various mixing conditions, were analyzed using the capillary rheometer. Results show that 54% volumetric Powder loading gave satisfactory flow properties when mixed at a temperature of 90°C with a rotor speed of 30 rpm.
Gang Fu - One of the best experts on this subject based on the ideXlab platform.
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micro Powder Injection moulding of alumina micro channel part
Journal of The European Ceramic Society, 2011Co-Authors: Junhu Meng, Gang FuAbstract:Abstract A feedstock consisting of submicron alumina Powder and a formulated binder, was developed to fabricate alumina micro-channel part by micro Powder Injection moulding. During small scale-mixing, the mixing torques of feedstocks with four different Powder loadings were used to establish a suitable Powder loading. The thermal and rheological properties of the selected feedstock were examined and used to establish conditions for large scale mixing, debinding and Injection moulding. The micro-channel parts were pressureless sintered at different temperatures. The results showed that the moulded, debound and sintered micro-channel parts had good shape retention. The dimensions of the micro-channel part changed with the different processing steps. High densification of the micro-channel parts was achieved at sintering temperatures of 1350 °C and above. Above 1350 °C, the grain grew significantly with increasing the sintering temperatures and thus it led to a decrease in the microhardness.
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characterisation of micro gears produced by micro Powder Injection moulding
Powder Technology, 2009Co-Authors: F. L. Ng, Gang Fu, X H LuAbstract:Abstract The paper describes the fabrication of micro gears of diameter and height 1 mm by micro Powder Injection moulding. 316L stainless steel Powder of 2.4 µm ( d 50 ) is mixed with a multi-component wax-based binder system. The feedstock is then Injection-moulded into micro gears followed by debinding and sintering. The microstructure of the micro gear at its tooth and hub is studied by electron backscattered diffraction. The average grain size at the hub is ~ 5 µm. However, a high content of annealing twin and a significant grain growth is found at the tooth.
Javier Ruiz Hidalgo - One of the best experts on this subject based on the ideXlab platform.
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optimisation of eco friendly binary binder system for Powder Injection moulding
Powder Metallurgy, 2014Co-Authors: C Abajo, Javier Ruiz Hidalgo, A Jimenezmorales, José M. TorralbaAbstract:In recent years, many efforts have been made to obtain more environmentally acceptable Powder Injection moulding processes. In this sense, the purpose of this study is to optimise an eco-binder based on polyethylene glycol (PEG) as a water soluble component and cellulose acetate butyrate (CAB) as a natural backbone polymer derived from cellulose for Powder Injection moulding of zirconium silicate Powders until a solvent debinding stage. Four different feedstocks have been investigated. As well as, a volume fraction of PEG and CAB 70/30 (vol.-%) and a solid loading of 57·5 (vol.-%) were maintained, molecular weights of polymers were combined in order to minimize distortion during binder solvent extraction. Water solvent debinding was carried out at three temperatures stepwise during 5 h. As a result, efficient removal of the PEG as well as free defects samples were obtained after solvent debinding for binder systems based on low molecular weight of PEG.
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thermal stability and degradation kinetics of feedstocks for Powder Injection moulding a new way to determine optimal solid loading
Polymer Degradation and Stability, 2013Co-Authors: Javier Ruiz Hidalgo, A Jimenezmorales, José M. TorralbaAbstract:Abstract Degradation kinetics and the thermal stability of zircon Powder Injection moulding feedstocks (PIM) based on cellulose acetate butyrate (CAB) and polyethylene glycol (PEG) binders were investigated using simultaneous thermogravimetric analysis (STA). The initial decomposition temperature (IDT) and the integral procedure decomposition temperature (IPDT) were used to analyse the thermal stability of the binder system as a function of the solid loading content. The degradation kinetics was studied, and the degradation activation energy was assessed for varying zircon Powder contents using isoconversional methods. All the methodologies revealed changes in the thermal degradation behaviours of the feedstocks for solid loadings that were previously determined to correspond to optimal solid loadings using other experimental procedures. These results may promote the proposal of thermodynamic degradation studies of feedstocks as an alternative or complementary technique to determine optimal solid loading contents in Powder Injection moulding (PIM). The studies in this paper also examined PIM process operation temperatures for zircon feedstocks.
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Powder Injection moulding processing of small parts of complex shape
International Journal of Microstructure and Materials Properties, 2013Co-Authors: José M. Torralba, Javier Ruiz Hidalgo, A JimenezmoralesAbstract:Powder Injection Moulding (PIM), Metal Injection Moulding (MIM) when is limited to metals, is a fabrication route of parts with the final shape desired. This process combines the high capability of polymer Injection moulding to produce complex shapes with the advantages of a Powder route to process metallic, ceramic or composites materials. The process has some limitations that comes from different technological steps involved in the production of the part (feedstock production, Injection, debinding and sintering). All of these different steps can be industrially controlled, being the PIM process a real alternative to produce complex parts in a high rate production method that can compete with many other processing methods to produce materials. In this work, we will go through the different steps of this manufacturing process, making special emphasis on the solutions provided by the Powder technology group of the University Carlos III of Madrid (UC3M).
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torque rheology of zircon feedstocks for Powder Injection moulding
Journal of The European Ceramic Society, 2012Co-Authors: Javier Ruiz Hidalgo, A Jimenezmorales, José M. TorralbaAbstract:Abstract In this work, a cellulose acetate butyrate (CAB) and polyethylene glycol (PEG) blend is used as the binder system in a zirconium silicate mineral Powder feedstock for Powder Injection moulding. These irregular zircon Powders make the mixing process and the selection of an optimal solid loading level a difficult task. Torque rheology methodologies combined with other techniques are used for evaluation of the parameters affecting the mixing process and determination of the critical Powder volume concentration (CPVC). Temperature variations during the mixing process are monitored and used as an indicator of the friction energy of the system and thus for the optimal solid loading selection. There have thus far been limited amounts of work conducted on torque rheology of highly loaded feedstocks that incorporate a study of the system's temperature evolution. A detailed study could be a key factor for understanding the mixing behaviour of highly loaded feedstocks.
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torque rheology of zircon feedstocks for Powder Injection moulding
Journal of The European Ceramic Society, 2012Co-Authors: Javier Ruiz Hidalgo, A Jimenezmorales, José M. TorralbaAbstract:Abstract In this work, a cellulose acetate butyrate (CAB) and polyethylene glycol (PEG) blend is used as the binder system in a zirconium silicate mineral Powder feedstock for Powder Injection moulding. These irregular zircon Powders make the mixing process and the selection of an optimal solid loading level a difficult task. Torque rheology methodologies combined with other techniques are used for evaluation of the parameters affecting the mixing process and determination of the critical Powder volume concentration (CPVC). Temperature variations during the mixing process are monitored and used as an indicator of the friction energy of the system and thus for the optimal solid loading selection. There have thus far been limited amounts of work conducted on torque rheology of highly loaded feedstocks that incorporate a study of the system's temperature evolution. A detailed study could be a key factor for understanding the mixing behaviour of highly loaded feedstocks.
Joonphil Choi - One of the best experts on this subject based on the ideXlab platform.
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design of trimodal fe micro nanoPowder feedstock for micro Powder Injection molding
Powder Technology, 2017Co-Authors: Joonphil Choi, Junil Song, Wonsik Lee, Jinsoo Park, Jai-sung LeeAbstract:Abstract The design of the trimodal Powder feedstock and its feasibility for micro Powder Injection molding (μ-PIM) were investigated. The feedstock was prepared by mixing Fe microPowder (D 50 = 4 μm) and nanoPowder agglomerate composed of a bimodal particle distribution (D 50 = 330 nm and D 50 = 30 nm, respectively) with low viscosity wax-based binders. The homogeneity of the feedstock was evaluated by torque rheometer, microstructure observations, binder burnout analysis, and an extrusion test. The trimodal concept in this study effectively improved the Powder loading up to 72 vol%, and the feedstock with 70 vol% Powder loading exhibited good homogeneity and flowability. By using the feedstock, the microparts were successfully replicated with sufficient shape retention to be potentially useful for a range of μ-PIM applications.
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sintering behavior of 316l stainless steel micro nanoPowder compact fabricated by Powder Injection molding
Powder Technology, 2015Co-Authors: Joonphil Choi, Geon-yong Lee, Junil Song, Wonsik Lee, Jai-sung LeeAbstract:Abstract The densification and grain growth behavior of Powder Injection molded 316L stainless steel micro–nanoPowder were investigated in terms of microstructural development. The sintered density of the micro–nanoPowder sample increased remarkably in the temperature range of 1000 to 1100 °C due to the sintering effect of nanoPowders which increased the number of grain boundaries acting as high material transport path. A near full density of 98% TD was obtained after sintering at 1100 °C for 5 h with the average grain size less than 10 μm, indicating that there was no drastic grain growth. The presence of nanoPowders in micro–nanoPowder played decisive role in the entire sintering process by enhancing densification but suppressing grain growth. These effects open up the possibility of using micro–nanoPowder feedstock to control the sintering behavior of Powder Injection molding products with full density and fine microstructure.
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evaluation of feedstock for Powder Injection molding
Japanese Journal of Applied Physics, 2014Co-Authors: Jin Man Jang, Jai-sung Lee, Wonsik Lee, Hyeongjae Lee, Yongin Kim, Jong Ha Kim, Joonphil ChoiAbstract:Methods to evaluate Powder Injection molding feedstock without performing the complete processing were developed to reduce the development-to-commercialization cycle time for feedstock. The mixing homogeneity of the Powder and binder, rheological properties, mechanical property and shape retainability during debinding were characterized to evaluate the feedstock. The validity of using these parameters was investigated through comparison with various feedstocks. Based on these results, the evaluation methods developed in this work have potential to aid in the selection of proper feedstock without undergoing the subsequent processing.