scholarly journals Development of Hypereutectic AlSi Alloy Powder Injection Molding Feedstocks by Rheological Analysis

2018 ◽  
Vol 2018 ◽  
pp. 1-9 ◽  
Author(s):  
Jiaqi Ni ◽  
Keqing Han ◽  
Muhuo Yu
Keyword(s):  
Injection Molding ◽  
Alloy Powder ◽  
Flow Behavior ◽  
Powder Injection Molding ◽  
Rheological Parameters ◽  
Powder Injection ◽  
Homogeneous Distribution ◽  
Constant Density ◽  
Flow Activation Energy ◽  
Comprehensive Properties

The comprehensive properties of a feedstock have a critical influence on the powder injection molding process. Proper feedstock with homogeneous structure, favorable flow characteristic, and moldability is the prerequisite for obtaining a final part with excellent comprehensive properties. The objective of the present work was to develop an optimal feedstock for fabrication of hypereutectic AlSi (20 wt.%) alloy parts by the powder injection molding technique. For this purpose, micron-sized hypereutectic AlSi (20 wt.%) alloy powder was mixed with different amounts of a binder which consisted of 35 wt.% high-density polyethylene, 62 wt.% carnauba wax, and 3 wt.% stearic acid. The binder contents of the feedstocks were in the range from 13 wt.% to 21 wt.%. The influences of binder content, shear rate, and temperature on the rheological behaviors of feedstocks have been investigated via a capillary rheometer. The feedstock with 21 wt.% binder exhibited a variable flow behavior and was culled. The rest of the feedstocks showed a pseudoplastic behavior. Comprehensive analysis of rheological parameters such as the flow behavior index, yield stress, flow activation energy, and the general moldability index, the feedstock with 17 wt.% binder exhibited the best rheological performance and favorable moldability. The molded part with 17 wt.% binder had constant density, good shape retention, and stiffness as well as homogeneous distribution of the powder and binder. After solvent debinding, the debound item showed a homogeneous porous structure which is suitable for the subsequent thermal debinding and sintering processes.

Rheological Analysis of Microminiature Powder Injection Molding (μPIM) Feedstock

2011 ◽  
Vol 52-54 ◽  
pp. 238-243 ◽  
Author(s):  
Haw Pei Li ◽  
Norhamidi Muhamad
Keyword(s):  
Activation Energy ◽  
Injection Molding ◽  
Power Law ◽  
Flow Behavior ◽  
Powder Injection Molding ◽  
Powder Injection ◽  
Flow Activation Energy ◽  
Rheological Analysis ◽  
Power Law Exponent ◽  
Flow Activation

A rheological analysis has been performed to evaluate the characteristics and behaviors of Microminiature Powder Injection Molding (μPIM) feedstocks. The feedstocks comprised of 316L stainless steel powder and water-based binder components. Feedstocks formulations with powder loading of 59% to 63% were prepared and investigated. In these formulations, the binder system consists of 65% Polyethelena Glycol (PEG), 25% Polymethyl Methacrilate (PMMA) and 10% Cellulose Acetate Butyrate (CAB) based on the weight fraction. The influences of rheological behaviors such as flow activation energy (E), Power-Law exponent (n), viscosity (η) and temperature (T) of the SS316L/PEG/PMMA/CAB feedstocks are analyzed and discussed. Results show that all of the feedstocks exhibited the pseudo-plastic flow behavior. The homogenous feedstock at 61 vol. % demonstrated the most satisfactory rheological properties for μPIM with the lowest flow activation energy, Power-Law exponent, n < 1 and moderate viscosity values. It was chosen to perform the injection molding process. Micro components have been replicated successfully by using this selected feedstock.

Powder Injection Molding of Ti-6Al-4V Alloy for Defect-Free High Performance Titanium Parts with Low Carbon/Oxygen Contents

2018 ◽  
Vol 770 ◽  
pp. 189-194
Author(s):  
Dong Guo Lin ◽  
Jae Man Park ◽  
Tae Gon Kang ◽  
Seong Taek Chung ◽  
Young Sam Kwon ◽  
...  
Keyword(s):  
Injection Molding ◽  
Alloy Powder ◽  
High Performance ◽  
Physical And Mechanical Properties ◽  
Powder Injection Molding ◽  
Powder Injection ◽  
Solid Loading ◽  
Injection Molding Process ◽  
Low Carbon ◽  
Molding Process

In this work, powder injection molding (PIM) of Ti-6Al-4V alloy powder has been studied. Defect-free high performance Ti-6Al-4V parts with low carbon/oxygen contents have been successfully prepared by PIM. A pre-alloyed Ti-6Al-4V alloy powder and wax-polymer binder system have been mixed together to prepare the feedstock. In mixing stage, the solid loading percentage and mixing conditions have been optimized. Rheological and thermal debinding behaviors of prepared feedstock have been characterized and numerically expressed based on rheometry and thermal gravity experimental results. In addition, the injection molding process of Ti-6Al-4V parts has been numerically analyzed to optimize the injection molding conditions. Consequently, the defect-free Ti-6Al-4V parts with low carbon and oxygen contents have been successfully fabricated by PIM, which exhibits excellent physical and mechanical properties.

Development of Recycled TiH2 Feedstock for Powder Injection Molding

2011 ◽  
Vol 291-294 ◽  
pp. 3024-3027 ◽  
Author(s):  
Bermha Cha ◽  
Jin Man Jang ◽  
Won Sik Lee ◽  
Jung Sik Seo ◽  
Se Hyun Ko ◽  
...  
Keyword(s):  
Injection Molding ◽  
Flow Behavior ◽  
Cost Effective ◽  
Powder Injection Molding ◽  
Powder Injection ◽  
Temperature Synthesis ◽  
Good Shape ◽  
Attrition Milling ◽  
High Temperature Synthesis ◽  
Processing Step

Powder Injection molding (PIM) is a cost-effective process for the fabrication of complex shaped parts, and has a great potential in many applications. In this work, an improved wax-based binder was developed for the powder injection molding of TiH2 powder fabricated by recycling of Ti chip. Fine TiH2 powders of about 350 nm in particle size were produced by attrition milling of Ti chip in less than five minutes, resulting from simultaneous self-propagating High temperature Synthesis (SHS) and fracturing. TiH2 feedstock, a mixture of binder and powders, was fabricated with critical powder loading of 68 vol.%. The rheological characteristics of the feedstock were investigated for subsequent processing step. Viscosity of the feedstock showed pseudo-plastic flow behavior and to optimize injection molding parameter, in-mold rheology curve was generated. The results indicated that the recycled TiH2 feedstock can be used for the fabrication of the complex shaped parts with good shape.

scholarly journals Flow Behavior of Cu/CNTs Feedstocks for Powder Injection Molding

2011 ◽  
pp. 199-202 ◽  
Author(s):  
Ali Samer Muhsan ◽  
Faiz Ahmad ◽  
Norani Muti Mohamed ◽  
M. Rafi Raza
Keyword(s):  
Injection Molding ◽  
Flow Behavior ◽  
Powder Injection Molding ◽  
Powder Injection

Ti-6Al-4V alloy bimodal powders for powder injection molding

2020 ◽  
Author(s):  
Elena Glazkova ◽  
Nikolay Rodkevich ◽  
Nikita Toropkov ◽  
Aleksandr Pervikov ◽  
Marat Lerner
Keyword(s):  
Injection Molding ◽  
Powder Injection Molding ◽  
Powder Injection

Investigation of final-stage sintering of various microsize structures prepared by micro powder injection molding

2010 ◽  
Vol 103 (4) ◽  
pp. 1145-1151 ◽  
Author(s):  
L. Liu ◽  
N. H. Loh ◽  
B. Y. Tay ◽  
S. B. Tor ◽  
H. Q. Yin ◽  
...  
Keyword(s):  
Injection Molding ◽  
Final Stage ◽  
Powder Injection Molding ◽  
Powder Injection

scholarly journals Molding Properties of Inconel 718 Feedstocks Used in Low-Pressure Powder Injection Molding

2016 ◽  
Vol 2016 ◽  
pp. 1-7 ◽  
Author(s):  
Fouad Fareh ◽  
Vincent Demers ◽  
Nicole R. Demarquette ◽  
Sylvain Turenne ◽  
Orlando Scalzo
Keyword(s):  
Shear Rate ◽  
Injection Molding ◽  
Inconel 718 ◽  
Rate Sensitivity ◽  
Low Pressure ◽  
Powder Injection Molding ◽  
Powder Injection ◽  
Sensitivity Index ◽  
High Shear Rates ◽  
The Impact

The impact of binders and temperature on the rheological properties of feedstocks used in low-pressure powder injection molding was investigated. Experiments were conducted on different feedstock formulations obtained by mixing Inconel 718 powder with wax-based binder systems. The shear rate sensitivity index and the activation energy were used to study the degree of dependence of shear rate and temperature on the viscosity of the feedstocks. The injection performance of feedstocks was then evaluated using an analytical moldability model. The results indicated that the viscosity profiles of feedstocks depend significantly on the binder constituents, and the secondary binder constituents play an important role in the rheological behavior (pseudoplastic or near-Newtonian) exhibited by the feedstock formulations. Viscosity values as low as 0.06 to 2.9 Pa·s were measured at high shear rates and high temperatures. The results indicate that a feedstock containing a surfactant agent exhibits the best moldability characteristics.

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