Critical powder loading and the rheology of nanosized cemented carbide with titanium carbide as grain growth inhibitor for injection molding

The purpose of this paper is to determine the critical powder loading of WC-Co and to study the effect of TiC powder on the rheological behavior of MIM feedstock. WC-TiC-6Co metal powder was taken as raw material. 60% (mass fraction) palm stearin and 40% low density polyethylene were employed as binders to prepare injection feedstock. Three feedstocks were prepared at different TiC % loadings of 0.5, 0.75, and 1.0 (by weight). A homogeneous metal powders is formed by using ball mill mixer and mixed together with binder system by using Brabender mixer. Based on the result obtained, it was concluded that feedstock with 0.75 wt. % TiC powder show a good pseudo-plastic behavior within acceptable ranges in MIM

Optimization of indoor air quality towards the control of mould formation by taguchi method

The formation of mould in an indoor environment is closely related to the poor Indoor Air Quality (IAQ) which can lead to various adverse health effects such as Sick Building Syndrome (SBS) and Building Related Illness (BRI). Hence, this study was conducted to investigate the relationship between mould formation and IAQ parameters in FKAAS building. The optimization of physical IAQ parameters such as air temperature (A), relative humidity (B) and air movement (C) is conducted by Taguchi Method with L9 Orthogonal Array (OA) at 3 different levels. The response output being measured is the level of carbon dioxide (CO2) and the noise factor was time at morning and evening. The data obtained has been referred to Malaysia Standard (ICOP-2010) and ASHRAE Standard 55-2013 to verify the IAQ contamination level. From the investigation, it was found that the optimized parameters are within the acceptable range of standard and the most significant factor towards the IAQ was air movement, followed by relative humidity and air temperature. The best optimized parameters can be noted as (A:1; B:3; C:3) which is air movement at 0.195 m/s, 61% of relative humidity and air temperature of 25.77 oC. As a conclusion, Taguchi method has proven to be a powerful tool to generate robust physical parameter of IAQ, regardless of time change. In addition, the IAQ parameter definitely influence the formation of mould, and was proven by various signs of visible mould formation which indicates the unhealthy state for the occupant to stay

Kajian pengoptimuman penyahikatan larutan menggunakan kaedah permukaan sambutan

Proses penyingkiran bahan pengikat polietilena glikol (PEG) dari padatan pengacuan suntikan logam dikaji pada pelbagai nilai beban serbuk, suhu larutan dan juga masa rendaman, atau pembolehubah tak bersandar. Rekabentuk gubahan memusat berputar digunakan untuk mengkaji kesan pembolehubah tersebut terhadap kekuatan jasad perang, atau pembolehubah bersandar. Kertas kerja ini membincangkan penggunaan Kaedah Permukaan Sambutan(RSM) dalam mengoptimumkan parameter pemprosesan penyahikatan larutan bagi padatan serbuk keluli tahan karat SS316L (saiz purata 19.6 µm) untuk mencapai kekuatan jasad perang yang maksimum. Berdasarkan nilai optimum yang diperolehi (beban serbuk 64% isipadu, suhu larutan sebanyak 59oC dan masa rendaman selama 3 jam), kekuatan jasad perang maksimum yang dicapai adalah 5 MPa. Beban serbuk memiliki kesan paling signifikan terhadap kekuatan jasad perang, diikuti masa rendaman dan suhu larutan. Kaedah ini memberi kemudahan dalam penyelidikan penyahikatan larutan pada masa akan datang terutamanya untuk menyingkirkan PEG dari jasad anum dengan hanya menggunakan persamaan matematik tanpa perlu melakukan ujikaji

Critical Powder Loading and the Rheology of Nanosized Cemented Carbide with Titanium Carbide as Grain Growth Inhibitor for Injection Molding

The purpose of this paper is to determine the critical powder loading of WC-Co and to study the effect of TiC powder on the rheological behavior of MIM feedstock. WC-TiC-6Co metal powder was taken as raw material. 60% (mass fraction) palm stearin and 40% low density polyethylene were employed as binders to prepare injection feedstock. Three feedstocks were prepared at different TiC % loadings of 0.5, 0.75, and 1.0 (by weight). A homogeneous metal powders is formed by using ball mill mixer and mixed together with binder system by using Brabender mixer. Based on the result obtained, it was concluded that feedstock with 0.75 wt.% TiC powder show a good pseudo-plastic behavior within acceptable ranges in MI

Pengoptimuman parameter pengacuan bagi mengurangkan kecacatan jasad anum proses pengacuan suntikan logam (MIM)

Injection molding parameters of the metal powder mixture has been optimized using L27 (313) orthogonal array. Parameters optimized were injection pressure, injection temperature, powder loading, mold temperature, holding pressure and injection speed. Metal powder mixture used is a bimodal SS316L, and polyethylene glycol (PEG), polymethyl methacrylate (PMMA) and stearic acid as binder. Beside those, interactions of the injection pressure, injection temperature and powder loading were studied. Pareto-Anova analysis for the smallest the best signal to noise ratio (S/N) presents the significance of each parameters and interactions. Results shows that the interaction between injection pressure and temperature has highest significant percentage (19.39 %) followed by interactions between injection pressure and power loading (17.77 %) and, injection temperature and powder loading (14.41 %). Beside those, injection rate was the single parameter that greatly influences the green part defects of 14.41 %, while injection pressure and holding pressure were less significant of about 0.27 % and 0.58 % respectively. Results shows that the optimum injection parameter was as follows: 350 bar (injection pressure); 150 oC (injection temperature); 64 % volume (powder loading); 51 oC (mold temperature); 700 bar (holding pressure); and 15 ccm/s (injection rate). Signal noise ratio at the optimum condition was -2.46 dB 2.05 at 90 % confidence interval. The optimum parameter has been confirmed by the confirmation experiment to ten samples and its signal noise ratio obtained was -255 dB which was within the optimal range

An influence of the SS316L powder particle shape to the densification of metal injection moulding (MIM) compact

Metal injection molding (MIM) has acquired increasing importance as a production technique for small, complex stainless steel components [1, 2]. Sintering is critical for determining the final quality of the parts produced by MIM. Because high sintered density is imperative for good mechanical properties and corrosion resistance, achieving full or near-full density has been a major objective of sintering [3]. Therefore, most research on 316L stainless steel sintering to date has focused on the sintering behavior of the molded parts especially for gas-atomised powder in argon environment [3-6]. An understanding of the factors influencing densification of stainless steels is important as over 50% of the injection molded and sintered components are made from stainless steel compositions [7]. In a metal injection molding (MIM) process, gas-atomised powder is generally used due to their high packing density and associated feedstock rheology. The sintered components exhibit mechanical and corrosion properties similar or superior to that of wrought material. Water-atomised powders in MIM can be economical and have an improvement in shape retention during debinding and sintering. However, their use comes with a penalty of lower powder loading and sintered density, with a corresponding degradation in the mechanical and corrosion properties. Studies reveal that injection molded and sintered components using water-atomised 316L stainless steel powders have a residual porosity of 3–5% for similar particle characteristics and sintering conditions as that of gas-atomised powders [5]. This article investigates a densification of SS316L gas and wateratomised compact sintered in high vacuum environment at temperature ranging from 1340 to 1400 °C

Kajian prestasi penyahikatan larutan dengan menggunakan kaedah taguchi

Proses penyahikatan larutan telah diterima secara meluas dalam proses pengacuan suntikan logam (MIM) berdasarkan kepada kemampuannya yang dapat mempercepatkan proses penyahikatan. Kertas kerja ini akan membentangkan pengoptimuman proses tersebut dengan menggunakan kaedah Taguchi. Selain daripada itu juga, pengaruh faktor-faktor yang digunakan dalam kajian ini seperti suhu larutan, taburan saiz partikel, beban serbuk dan tekanan penyuntikan akan dibincangkan. Dua jenis serbuk logam akan digunakan dalam kajian ini iaitu serbuk SS316L pengatoman gas dan SS316L pengatoman air. Keputusan kajian ini mendapati bahawa suhu larutan yang digunakan untuk merendam jasad anum semasa proses penyahikatan larutan memainkan peranan yang besar sebanyak 91.602 % (serbuk SS316L pengatoman gas) dan sebanyak 84.978 % (serbuk SS316L pengatoman air) ke atas kadar penyahikatan larutan. Bagaimanapun, taburan serbuk logam hanya menyumbangkan sebanyak 6.638 % dan 12.228 % masing-masing bagi jasad anum serbuk SS316L pengatoman gas dan pengatoman air terhadap kadar penyahikatan tersebut. Suhu larutan untuk merendam jasad anum ini juga mempunyai tahap signifikan yang amat tinggi iaitu sebanyak 0.5% bagi kedua-dua jenis serbuk SS316L tersebut. Akan tetapi, taburan saiz partikel serbuk SS316L menunjukkan tahap signifikan yang sederhana tinggi iaitu 2.5% dan 1% bagi serbuk SS316L pengatoman gas dan pengatoman air masing-masing

Rheological properties of SS316l MIM feedstock prepared with different particle sizes and powder loadings

Rheological study has been performed experimentally to evaluate the influence of different particle sizes and powder loadings to the rheological properties of SS316L MIM feedstock. The effects of different particle size, powder loading, shear rate and temperature has been investigated using capillary rheometer. The effect of shear rate to the feedstock viscosity was evaluated and result demonstrated that the feedstocks are pseudo-plastic. Their viscosity also shows strong dependence on the shear rate. The activation energy of each feedstock indicates the sensitivity to temperature and shear stress. The moldability index of the feedstock is also significant. The results indicate that the high powder loading feedstock at 64% volumes demonstrate the best rheological properties. The feedstock achieved desirable injection molding characteristics, such as homogeneous, stable, flow behavior index, n < 1, moderate activation energy (E) and high moldability index (a)

Particle size and injection temperature effect on the injection molding of SS316l powder

Particle size and injection temperature influence on the injection of SS316L powder has been investigated. The feedstocks used for the investigation being 64 vol. % and 65 vol. %. Results found that the success of the molding process depends on the feedstock rheological properties. Fine powder particles at 64 vol. % demonstrated higher temperature sensitivity than the coarse powder feedstock. However, the coarse powder feedstock shows its sensitivity to the injection pressure. The investigation found that the injection temperature has its influence to the final quality of the compact. Injection temperature of 140 oC was found to be the optimum. However, the investigation does not found any significant on the injection temperature to the debinding rate

Pemilihan bahan suapan bagi proses pengacuan suntikan logam berdasarkan kepada kajian sifat reologi

Rheological properties of the metal injection molding (MIM) feedstock prepared with gas atomized 316L stainless steel and, polymethyl methacrylate (PMMA), polyethylene glycol (PEG) and stearic acid as binder have been investigated. Capillary rheometer with die of L/D = 10 was used in the investigation. Coarse and fine stainless steel powders were mixed with binders at powder loading of 64% and 65% volume. All feedstocks exhibit pseudo plastics behaviour as the flow behaviour indexes were less than one, but it is inversely proportional to the powder loading. Moreover, the flow behaviour index of the coarse powder is larger than the fine powder particles. Feedstock 16_64 exhibits higher sensitivity among other feedstocks while 31_65 was least sensitive to the temperature and pressure. However, the sensitivity was alsoinversely proportional to the powder loading. Thus, moldability index of the 31_64 is the best and result shows that powder loading 64% volume gives better moldability to the feedstocks. Finally, the investigation concluded that the feedstocks are suitable to be injection molded because the rheological properties demonstrate a shear thinning when subjected to shear stress. However, feedstock with the powder loading of 64% volume is the most suitable as the moldability index is higher than the 65% volume feedstocks