Filling of Microarray Fabricated by Micro Powder Injection Molding

2017 ◽  
Vol 898 ◽  
pp. 1171-1176 ◽  
Author(s):  
Lin Liu ◽  
M.X. Qi ◽  
Z.Q. Xie ◽  
Z.Y. He ◽  
F. Ming
Keyword(s):  
Injection Molding ◽  
Volume Fraction ◽  
Fluid Model ◽  
Flow Analysis ◽  
Mold Temperature ◽  
Powder Injection Molding ◽  
Powder Injection ◽  
Two Fluid Model ◽  
Micro Pillars ◽  
Micro Cavity

Flow analysis during injection molding is crucial for dimensional control in micro powder injection molding. Numerical simulation of injection molding of ZrO2 microarray based on in-house feedstock was conducted. A powder-binder two fluid model was developed to analyze temperature, viscosity and powder volume fraction of the feedstock for micro pillars of different dimensions with diameters of 0.2, 0.5 and 1 mm, respectively. In general the binder temperature decreased with size reduction of the micro cavity caved on the silicon wafer and increased with mold temperature. The micro pillars of φ0.2 mm exhibited the highest viscosity, which indicated difficulty for filling during injection molding. An increase in mold temperature facilitated the decrease of the feedstock viscosity, which improved the filling of the micro cavities. Powder-binder segregation became evident as the size of the micro cavities reduced to 0.2 mm.

Analysis of Powder Segregation in Powder Injection Molding

2011 ◽  
Vol 217-218 ◽  
pp. 1372-1379
Author(s):  
Yu Hui Wang ◽  
Xuan Hui Qu ◽  
Wang Feng Zhang ◽  
Yan Li
Keyword(s):  
Fluid Flow ◽  
Injection Molding ◽  
Volume Fraction ◽  
Fluid Model ◽  
Powder Injection Molding ◽  
Powder Injection ◽  
Exchange Term ◽  
Mixture Density ◽  
Two Fluid Model ◽  
Two Fluid

The powder injection molding (PIM) combines the thermoplastic and powder metallurgy technologies to manufacture intricate parts to nearly shape. The powder segregation is a special effect arising in PIM different from than the pure polymer injection. The two-fluid flow model is used to describe the flows of binder and powder so as to realize the prediction of powder segregation effect in PIM injection. To take into account binder–powder interaction, the mixture model of inter-phase exchange term is introduced in the two-fluid model. The two-fluid equations largely resemble those for single-fluid flow but are represented in terms of the mixture density and velocity. The volume fraction for each dispersed phase is solved from a phase continuity equation. As the key to calculate the phase exchange term, the drag coefficient is defined as a function of mixture viscosity. The effective viscosity of binder and powder are agreed with the additive principle. The volume fractions of binder and powder give directly the evolution of segregation during the injection course. Segregation during PIM injection was simulated by software CFX and results were compared with experimental data with good agreement. The basic reasons that caused segregation are identified as boundary effect, differences in density and viscosity of binder and powder. The segregation zones are well predicted. This showed that the two-fluid model is valid and efficient for the prediction of the segregation effects in PIM injection.

scholarly journals Effects of Cr and B Contents on Volume Fraction of (Cr,Fe)2B and Hardness in Fe-Based Alloys Used for Powder Injection Molding

2012 ◽  
Vol 43 (7) ◽  
pp. 2237-2250 ◽  
Author(s):  
Jeonghyeon Do ◽  
Hyuk-Joong Lee ◽  
Changwoo Jeon ◽  
Dae Jin Ha ◽  
Choongnyun Paul Kim ◽  
...  
Keyword(s):  
Injection Molding ◽  
Volume Fraction ◽  
Powder Injection Molding ◽  
Powder Injection

Fabrication and Bending Strength of Al/SiC Composites with High Volume Fraction of Reinforcement by Combining Powder Injection Molding and Pressure Infiltration

2011 ◽  
Vol 189-193 ◽  
pp. 2945-2948
Author(s):  
Liang Xiong ◽  
Hao He ◽  
Yi Min Li
Keyword(s):  
Particle Size ◽  
Injection Molding ◽  
Bending Strength ◽  
Volume Fraction ◽  
High Volume ◽  
Powder Injection Molding ◽  
High Volume Fraction ◽  
Powder Injection ◽  
Pressure Infiltration ◽  
Sic Composites

The paper presents the result of an experimental investigation on the fabrication of Al/SiC composites with high volume fraction of SiC particles by pressure infiltration of liquid aluminum into preforms prepared by powder injection molding (PIM). To obtain the required high particle volume fraction, SiC powders with a bimodal particle size distribution were used. The influence of powder loading and particle size on the bending strength of the prepared composites has been investigated. It is demonstrated that pressure infiltration permits to achieve high relative densities for the composites (i.e. 98.8%). The microstructure studies revealed a uniform distribution of SiC particles in the composites without interface reactions between the particles and the aluminum matrix. The bending strength increases with increasing powder loading and decreasing particle size of the coarse powders in the bimodal powder system.

Thermo-Physical Properties of SiCAl Composites with High Volume Fraction of Reinforcement Prepared by Combining Powder Injection Molding and Pressure Infiltration

2011 ◽  
Vol 239-242 ◽  
pp. 1832-1837
Author(s):  
Hao He ◽  
Yi Min Li
Keyword(s):  
Particle Size ◽  
Injection Molding ◽  
Physical Properties ◽  
Volume Fraction ◽  
High Volume ◽  
Powder Injection Molding ◽  
Powder Injection ◽  
Pressure Infiltration ◽  
Johnson Model ◽  
Thermo Physical Properties

SiC/Al composites with high reinforcement content were fabricated by pressure infiltration of aluminum alloy into porous SiC preform obtained by powder injection molding using a bimodal powder mixture. The influence of powder loading and particle size on the thermo-physical properties of the prepared composites was investigated. The results indicate that the thermal conductivities (TC) increases and coefficients of thermal expansion (CTE) decreases with increasing powder loading and particle size of the coarse powders in the bimodal powder system. The TCs are below the estimated value based on Hasselman-Johnson model, mainly due to the residual pores and the irregular particle shape. The CTEs of the composites increase with increasing temperature from 100°C to 400°C, and the increasing rates vary at different temperature ranges. Deep cooling in liquid nitrogen is effective to bring dislocations in the matrix and thus reduces the CTEs.

Powder Injection Molding of Cu-Based Amorphous Powders and Fe-Based Metamorphic Powders

2008 ◽  
Author(s):  
Chang-Young Son ◽  
Chang Kyu Kim ◽  
Dae Jin Ha ◽  
Tae Shik Yoon ◽  
Sunghak Lee ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Wear Resistance ◽  
Injection Molding ◽  
Volume Fraction ◽  
Powder Injection Molding ◽  
Powder Injection ◽  
Austenitic Matrix ◽  
Amorphous Phases ◽  
Amorphous Powders ◽  
Injection Molded

Powder injection molding (PIM) process was applied to Cu-based amorphous alloy powders and Fe-based metamorphic alloy powders, and microstructure, hardness, and wear resistance of the PIM products were analyzed. When Cu-based amorphous powders were injection-molded and sintered at 470 °C, sintering was not made since most of amorphous phases were replaced by crystalline phases. When sintered at higher temperatures, volume fraction of pores inside the sintered specimens decreased, but sintering was not properly conducted. When Fe-based metamorphic powders were injection-molded and then sintered at 1200 °C, completely densified products with almost no pores were obtained. They contained 34 vol.% of (Cr, Fe)2B borides dispersed in the austenitic matrix without amorphous phases. Since these (Cr, Fe)2B borides were hard and thermally stable, hardness, high-temperature hardness, and wear resistance of the PIM products of Fe-based metamorphic powders were twice as high as those of conventional PIM stainless steel products. These findings suggested new applicability of the PIM products of Fe-based metamorphic powders to structures and parts requiring excellent mechanical properties.

scholarly journals Simulation on the Two-phase Separation of Powder Injection Molding 316L Stainless Steel

2019 ◽  
Vol 25 (3) ◽  
pp. 246-251 ◽  
Author(s):  
Feng SHANG ◽  
Bin QIAO ◽  
Yan-feng DONG ◽  
Zhen-wei CAO ◽  
Wei SUN ◽  
...  
Keyword(s):  
Stainless Steel ◽  
Phase Separation ◽  
Injection Molding ◽  
316L Stainless Steel ◽  
Volume Fraction ◽  
Solid Volume Fraction ◽  
Powder Injection Molding ◽  
Powder Injection ◽  
Two Phase ◽  
Simulation Results

By utilizing the FLUENT software, finite element simulation analysis was performed on the two-phase separation of powder injection molding, and the simulation results were verified through experiment. As indicated in the simulation results, the optimal process parameters for the injection molding of 316L stainless steel sample were to inject at 70 MPa and 140 °C, at an injection speed of 3.49 cm3/s. Under these conditions, the maximum average solid volume fraction in observation area of the sample was 57.68 %. Additionally, it was discovered that while preparing 316L stainless steel was prepared by powder injection molding, the smaller the average porosity of the sample, the greater the Vickers hardness. And then the higher the average solid volume fraction simulated the slighter the two-phase separation between the powder and the binder. DOI: http://dx.doi.org/10.5755/j01.ms.25.3.19137

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
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