Characterization and Rheological Studies on Ready-Made Feedstock of Stainless Steel 316L in Metal Injection Molding (MIM) Process

2013 ◽  
Vol 465-466 ◽  
pp. 709-714 ◽  
Author(s):  
N.H. Mohamad Nor ◽  
Muhammad Hussain Ismail ◽  
Nur Atikah Abu Kasim ◽  
N. Muhamad ◽  
M.A. Taib

Current trend for manufacturers associated to MIM industry try to enhance the feedstock in term of its characteristics, since it is the most crucial part of the MIM process. This paper covered the characterization and rheological studies on a ready-made feedstock of stainless steel 316L which is vital to determine the availability and suit the needs of many advanced applications. There are three different experiments involved which are Scanning Electron Microscope (SEM), Differential Scanning Calorimeter (DSC), Thermogravimetric (TGA) and Capillary Rheometer. Observation through SEM gives an insight of the bonding microstructure matrices of the feedstock and also determines the homogeneity of the feedstock. DSC testing defines the melting temperature of the 3 binders used which are 62.07°C for surfactant, 178.72°C for filler and 236.61°C for backbone binder. From TGA result, it showed that the total weight loss of feedstock was 39%. Throughout the capillary rheometer testing, the feedstocks viscosity was decreasing as the shear rate increasing. The feedstock exhibits pseudoplastic behaviour since its flow behaviour index was less than 1. It is founded that at the temperature of 190°C, the feedstock exhibits the best characteristics for injection.

Author(s):  
Norhamidi Muhamad ◽  
Khairur Rijal Jamaludin ◽  
Sri Yulis M. Amin ◽  
Mohd Nizam Ab. Rahman

Sifat reologi bahan suapan acuan suntikan logam MIM yang disediakan dengan keluli tahan karat 316L pengabusan gas dan, polymethyl methacrylate (PMMA), polietelena glikol (PEG) dan asid sterik sebagai bahan pengikat telah dikaji. Dai kapilari L/D = 10 telah digunakan dalam kajian ini. Serbuk keluli tahan karat kasar dan halus telah diadunkan dengan bahan pengikat pada beban serbuk 64% dan 65% isipadu. Kesemua bahan suapan mempamerkan tingkahlaku pseudo plastik memandangkan indek tingkahlaku alirannya kurang daripada 1, tetapi indek tersebut berkadar songsang terhadap beban serbuk. Seterusnya, indek tingkahlaku bagi serbuk kasar didapati lebih besar berbanding serbuk halus. Bahan suapan 16_64 lebih peka berbanding bahan suapan yang lain, dan bahan suapan 31_65 pula didapati kurang peka terhadap suhu dan tekanan. Bagaimanapun, kepekaan juga didapati berkadar songsang terhadap beban serbuk. Maka, indek kebolehacuan bagi 31_64 adalah yang terbaik, dan hasil kajian mendapati bahawa beban serbuk 64% isipadu menghasilkan kebolehacuan bahan suapan yang lebih baik. Akhirnya, kajian ini menyimpulkan bahawa kesemua bahan suapan sesuai untuk disuntik ke dalam acuan kerana sifat reologinya menunjukkan penipisan ricih apabila tegasan ricih dikenakan terhadapnya. Bagaimanapun, bahan suapan pada beban serbuk 64% isipadu adalah yang lebih sesuai disebabkan oleh indek kebolehacuan yang lebih tinggi daripada 65% isipadu. Kata kunci: Pengacuan suntikan logam, reologi, indek tingkahlaku aliran, tenaga pengaktifan, indek kebolehacuan 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 also inversely 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. Key words: Metal injection molding, rheology, flow behaviour index, activation energy, moldability index


2014 ◽  
Vol 607 ◽  
pp. 83-86 ◽  
Author(s):  
Rosli Asmawi ◽  
Mohd Halim Irwan Ibrahim ◽  
Azriszul Mohd Amin

This paper describes the mixing process and homogeneity analysis of a newly developed binder system based on waste polystyrene (PS) and palm kernel oil (PKO) to produce feedstock for metal injection molding (MIM). Since mixing is a critical step in MIM process, hence the mixture of powder and binder should be homogeneous and injectable. In this study, water atomised Stainless Steel powder was mixed with a new binder system consisting of waste polystyrene and palm kernel oil in a Brabender Plastograph EC rotary mixer. Several tests were performed to assess the homogeneity of the feedstock that was produced at 60 vol.% powder loadings. The 60 vol.% was chosen because the Critical Powder Volume Concentration (CPVC) of the SS316L powder was found to be 64.8 vol.%. The tests conducted were density, binder burn-out and SEM morphology observation. It was found that the feedstock shows good homogeneity and suitable for further processing in MIM.


2011 ◽  
Vol 314-316 ◽  
pp. 713-718 ◽  
Author(s):  
Zhi Qiang Cheng ◽  
Cedric Quinard ◽  
Xiang Ji Kong ◽  
Thierry Barriere ◽  
Bao Sheng Liu ◽  
...  

The viscous behavior of feedstocks plays the crucial role in Micro MIM. It affects directly injectability of the components and finally quality of the sintered component, because of the possible segregation induced by injection. The studies on viscosity of the feedstocks are realized by a series of the tests, in which a torque rheometer and a capillary rheometer are employed. The effects of binder composition, powder size, temperature and powder loading in volume on viscosity of the feedstocks are investigated. The mixtures of three kinds of binder composition, mixed with 5µm or 16µm 316L stainless steel powders, are evaluated. The best binder composition is determined by comparison of the viscous behaviors among the self-mixed feedstocks and the commercial one. It results in the suitable ranges of heating temperature and powder loading in volume for the feedstocks. The critical powder loading in volume is determined by a series of the capillary tests with the gradual increase of powder loading. These works provide the valuable reference for the research on binder composition and the process of micro metal injection molding.


2012 ◽  
Vol 15 (3) ◽  
pp. 112-122
Author(s):  
Ali H. Ataiwi ◽  
◽  
Abdul Khaliq F. Hamood ◽  
Rana A. Majed ◽  
◽  
...  

Author(s):  
M. Carraturo ◽  
G. Alaimo ◽  
S. Marconi ◽  
E. Negrello ◽  
E. Sgambitterra ◽  
...  

AbstractAdditive manufacturing (AM), and in particular selective laser melting (SLM) technology, allows to produce structural components made of lattice structures. These kinds of structures have received a lot of research attention over recent years due to their capacity to generate easy-to-manufacture and lightweight components with enhanced mechanical properties. Despite a large amount of work available in the literature, the prediction of the mechanical behavior of lattice structures is still an open issue for researchers. Numerical simulations can help to better understand the mechanical behavior of such a kind of structure without undergoing long and expensive experimental campaigns. In this work, we compare numerical and experimental results of a uniaxial tensile test for stainless steel 316L octet-truss lattice specimen. Numerical simulations are based on both the nominal as-designed geometry and the as-build geometry obtained through the analysis of µ-CT images. We find that the use of the as-build geometry is fundamental for an accurate prediction of the mechanical behavior of lattice structures.


2021 ◽  
pp. 102104
Author(s):  
Xianglong Wang ◽  
Oscar Sanchez-Mata ◽  
Sıla Ece Atabay ◽  
Jose Alberto Muñiz-Lerma ◽  
Mohammad Attarian Shandiz ◽  
...  

Sign in / Sign up

Export Citation Format

Share Document