Ceramic Powder Injection Research Articles

Physics of Ceramic Powder Injection Molding Technology

Physics of Ceramic Powder Injection Molding Technology

Real-time Diagnosis of Micro Powder Injection Molding Using Integrated Ultrasonic Sensors

Abstract Real-time diagnostics of ceramic powder injection molding using a commercial micromolding machine was performed using ultrasound. Miniature ultrasonic sensors were integrated onto the mold insert. Melt front, solidification, temperature variation and part detachment of the feedstock inside the mold cavity were observed. It has been demonstrated that ultrasonic velocity in feedstock inside the mold cavity, the ultrasonic contact duration during which the part and mold are in contact, and holding pressure can be used to assist with optimization of injection and cooling parameters to minimize energy consumption and maximize process efficiency.

Bio-inspired 3D funnel structures made by grayscale electron-beam patterning and selective topography equilibration

Electron beam grayscale lithography and selective thermal polymer reflow were combined to realize replication master having a bio-inspired surface topography. It consists of an array of asymmetric denticles with two-directional gradients on different length-scales. Each denticle has a sharp pin of 2μm height on one and a smooth taper on the other side. In contrast to funnel-like structures having only vertical sidewalls, master with a sidewall angle smoothly changing between 15° and 70° were prepared. Discrete patterns, predefined by electron beam lithography, were transformed by reflow into well-defined, continuous, final device structures. Starting from stepped structures with only a few levels, this new approach of tapering allowed a very smooth transition from steep, sub-500nm regions with aspect ratios up to four towards very broad and shallow regions within the same structure. This enabled the origination of master structures to be used for replication as low-frictional, durable, bio-inspired surfaces by ceramic powder injection molding.

Simulation of Ceramic Powder Injection Moulding Based on the Behavior of Flow Stress Depended on the Thermal Viscosity Flowage Property and the Volume Fraction

The prediction of flow pattern and volume fraction distribution in ceramic powder injection moulding (CIM) is very important because their characteristics affect the mechanical stiffness and the sintering shrinkage. The definition of feedstock behavior in the simulation of CIM depends on the various parameters such as temperature, strain rate and volume fraction. The aim of this study is to generate the governing equation based on non-newtonian flow model and predict the distribution of volume fraction from the result of CIM simulation using the subroutine of finite element package. Material parameters of governing equation are obtained from the compressive test of feedstock. Initial volume fraction is defined as the value of 0.5 referred to experimental data. In the boundary condition, the velocity of injection is 3 mm/s and the frictional coefficient between the feedstock material and the die is assumed as the value of 0.7 which means the value in the condition of cold moulding. The flow pattern of feedstock is very consistent with the experimental result. The result indicates that the range of volume fraction is from 0.42 to 0.58 depended on the pressure distribution. This result aids to predict the material stiffness according to the location of product from the relationship of the volume fraction and stiffness via Micro-hardness test.

Simulation of Ceramic Powder Injection Moulding Based on the Behavior of Flow Stress Depended on the Thermal Viscosity Flowage Property and the Volume Fraction

The prediction of flow pattern and volume fraction distribution in ceramic powder injection moulding (CIM) is very important because their characteristics affect the mechanical stiffness and the sintering shrinkage. The definition of feedstock behavior in the simulation of CIM depends on the various parameters such as temperature, strain rate and volume fraction. The aim of this study is to generate the governing equation based on non-newtonian flow model and predict the distribution of volume fraction from the result of CIM simulation using the subroutine of finite element package. Material parameters of governing equation are obtained from the compressive test of feedstock. Initial volume fraction is defined as the value of 0.5 referred to experimental data. In the boundary condition, the velocity of injection is 3 mm/s and the frictional coefficient between the feedstock material and the die is assumed as the value of 0.7 which means the value in the condition of cold moulding. The flow pattern of feedstock is very consistent with the experimental result. The result indicates that the range of volume fraction is from 0.42 to 0.58 depended on the pressure distribution. This result aids to predict the material stiffness according to the location of product from the relationship of the volume fraction and stiffness via Micro-hardness test.

Powder injection moulding of metallic and ceramic micro parts

Industrial use of micro components is determined by the availability of efficient manufacturing techniques. While micro injection moulding of plastic is common practice, metal and ceramic powder injection moulding (PIM) still is under development. High-pressure and low-pressure injection moulding methods complement each other ideally, covering the entire spectrum from prototype to large-scale production. With high-pressure PIM, micro gear wheels with diameters <300 μm can be fabricated using LIGA mould inserts. Densities between 97 and 99% of the theoretical values are achieved. Apart from oxide ceramics, metal materials like copper or powder metallurgical steels like 17-4PH or 316L are often applied. Multi-component injection moulding requires less mounting steps and, hence, offers decisive advantages for effective production of interesting material combinations like electrically conductive/insulating or hard/ductile. Studies relating to the fabrication of immobile as well as mobile shaft-wheel components were performed. Other activities focussed on in-mould labelling with foils containing ultra-fine particles to improve surface quality and detail accuracy. Low-pressure injection moulding allows for the manufacture of small series within 1–4 weeks at low cost. However, the process has features which are not compatible with high-pressure PIM. Although use of a low-viscous feedstock is associated with various benefits, low-pressure injection moulding has not met with acceptance in micro moulding.

Real-time Diagnosis of Micro Powder Injection Molding Using Integrated Ultrasonic Sensors

Abstract Real-time diagnostics of ceramic powder injection molding using a commercial micromolding machine was performed using ultrasound. Miniature ultrasonic sensors were integrated onto the mold...

Effects of Organotitanate Additions on the Dispersion of Aluminum Nitride in Nonpolar Solvents

Organotitanate additives are known to reduce the viscosity of many filled polymer systems, including formulations of interest for ceramic powder injection molding. Mineral oil was used as a model solvent for these systems to examine the effects of Organotitanate additions on the stability and rheology of A1N dispersions. Addition of the titanate coupling agents neoalkoxy tri(neodecanoyl) titanate and neoalkoxy tri(dioctylphosphato) titanate resulted in better dispersion as measured by sedimentation tests and rheological characterizations. Excellent correlation of the sediment heights and measured viscosities with adsorption isotherms for the organotitanates was shown, with both lower sediment height and lower viscosity obtained when a monolayer of the titanate molecules was present on the powder surface. Comparison of the behavior of the mineral oil based systems with the viscosity of corresponding polypropylene based binder systems indicates that the titanate additions are effective in reducing particle‐particle interaction effects in both systems.