An influence of a binder system to the rheological behavior of the SS316l Metal Injection Molding (MIM) feedstock

The influence of a binder system to the rheological behavior of a metal injection molding (MIM) feedstock is presented in the paper. The binder systems used are: a) PEG & PMMA b) Palm stearin & LLDPE and, c) Tapioca starch & LLDPE. The viscosity and shear rate of the feedstocks were measured at various range of temperature and shear rate across the L/D = 10 capillary rheometer. The flow behavior index, n and activation energy, E of each feedstock were measured to show its significance as MIM feedstock. Generally, the result indicates all feedstock exhibits a shear thinning behavior and the binders are suitable as MIM binder. Additionally, the present paper has discovered that the binder system does not have much influence to the activation energy. In order to show the relevance of the rheological bahavior to the actual injection molding performance, green parts has been injection molded and the results shows an agreement with the rheological behavior result

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

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 a binder system to the rheological behavior of the SS16l metal injection molding (MIM) feedstock

The influence of a binder system to the rheological behavior of a Metal Injection Molding (MIM) feedstock is presented in the paper. Three different types of binder systems are used consist of: a) PEG & PMMA b) Palm stearin & LLDPE and, c) Tapioca starch & LLDPE. The viscosity and shear rate of the feedstocks were measured at various range of temperature and shear rate across the L/D = 10 capillary rheometer. The flow behavior index, n and activation energy, E of each feedstock were measured to show its significance as MIM feedstock. Generally, the result indicates all feedstock exhibits a shear thinning behavior and the binders are suitable as MIM binder. Additionally, the present paper has discovered that the binder system does not have much influence to the activation energy. In order to show the relevance of the rheological behavior to the actual injection molding performance, green parts has been injection molded and the result shows an agreement with the rheological behavior resul

Perontokan biji kapuk dengan sistim transmisi rantai dibandingkan dengan sitim tradisional

v+17hlm.;29c

Rheological behavior of SS316l gas atomized powder in bimodal particle size distribution in a composite binder system

Rheological properties of the monomodal and bimodal MIM feedstock are presented in this paper. Coarse and fine SS316L gas atomized powders are mixed with PEG and PMMA to form a homogenous paste, which is termed as feedstock. The surface active agent used here is stearic acid. The bimodal powders are blended from 30 to 70 % of the coarse powder distribution. Results show that monomodal feedstock exhibits a higher viscosity over the bimodal feedstock at low shear rate. Binder separation is also likely to occur in the monomodal feedstock prepared with coarse powder especially at a high injection temperature. Furthermore, bimodal feedstock is less viscous than the monomodal feedstock but the particle size distribution has shown its influence on viscosity. The flow behavior index decreases when the temperature increases. The investigation also shows that the feedstock flow sensitivity depends on the fine powder distributions in the feedstock. Since all the feedstock demonstrates a good pseudo plastic behavior, it therefore is suitable to be injection molded

Feedstock characterisation of titanium alloy mix with palm stearin binder system for metal injection moulding

This paper presents the characterization of MIM feedstock consisting 90wt% of titanium alloy (Ti-6Al-4V) powder mix with binder 60wt% palm stearin and 40wt% polyethylene. The characterization of Ti-6Al-4V alloy powder, binders and feedstock includes scanning electron micrograph (SEM), thermogravimetric analysis (TGA), differential scanning calorimeter (DCS) and rheological test were established. Rheological results exhibited pseudoplastic or shear thinning flow behaviour, where its viscosity decreased with increasing shear rate. The feedstock viscosity also decreased with increasing temperature and was found to be suitable for mouldin

A review of workability of wrought magnesium alloys

Despite being the lightest structural metal, magnesium alloys exhibited poor workability at low temperatures due to their hexagonal closed-packed crystal structure, consequently required them to be processed at elevated temperature. Their highly affinity to oxygen lead them to an easy oxidation. Moreover, they are poor corrosion resistance, poor creep resistance as well as fatigue failure but these can be improved by various techniques of surface treatments and alloying additions. Commercial wrought magnesium alloy grades, its mechanical properties as well as its workability at elevated temperatures are presented. Recent literatures showed that the workability of these alloys is increased at temperatures ranging from 100 to 3500C, 200 to 400 to 300 to 5000C and for AZ, ZK and WE alloy systems, respectively. The purpose of this paper is to review and reveal the issues in processing of wrought magnesium alloy

Moulding parameter optimisation for the best sintered density

Injection moulding parameters that simultaneously satisfy green part qualities (green defect, green strength and green density) have been optimised using L27 (313) Taguchi orthogonal array. Moulding variables involved in the optimisation are the moulding pressure, moulding temperature, mould temperature, holding pressure, moulding rate, holding time and cooling time. The analysis of variance (ANOVA) is employed to determine the significant levels (a) and contributions of the variables to the green qualities. Results show that the mould temperature and holding time is highly significant simultaneously to the green qualities, while the holding pressure and cooling time does not show any significance. Besides that, densification of the compact moulded with the optimised moulding parameter is presented in this paper. With sintering temperature ranging from 1340 to 1400 °C while heating rate and dwell time remains at 10 °C/min and 4 hours respectively demonstrates that the optimised moulding parameter is enabled to produce a sintered part with a density which is very close to the solid density of SS316L