Papers by Keyword: Micro Injection Moulding

Abstract: Micro injection moulding is a key technology for mass-production of micro structured surfaces, such as optical and microfluidic devices. The manufacturing of a microstructured master mould with traditional technologies poses challenges about durability, accuracy and high - volume production. This paper introduces a new approach to realize micro mould inserts in a fast and economical way. Suitable engineered materials as alternative inserts to the metallic one are proposed exploiting the following new strategy: a thermosetting epoxy resin from renewable sources was synthesized and used to realize the mould insert via casting. The initial low viscosity of the liquid epoxy resin precursors allows the achievement of a high fidelity replica of different micro structures and provides an inexpensive and convenient route for rapidly duplicate master mould. A staggered harringbone (SHM) micro-mixer geometry was replicated and the epoxy based resin insert withstood 900 moulding cycles showing good features replication and durability.

Abstract: Powder injection molding (MicroPIM) has a considerable potential for the production of high-value metal and ceramic micro components. This does not only apply to technical aspects but, due to the deployability of mass production, also to economic ones. The current status can be summed up by the following key data: latest trials revealed smallest struc-tural details in the 10µm range or lower. Theoretical densities of up to 99% were achieved depend-ing on the particular powder applied. Typical materials processed are metals (Fe, Cu, 316L, 17-4PH, W and W-alloys etc.) or ceramics (aluminum/zirconium oxide etc.). Best surface qualities were obtained with ultrafine or even nano-doped ceramic powders. Another major line of development is multi-component or assembly injection molding. These proc-esses do not only reduce assembly expenditure, but also allow for the use of new functional material combinations. Interesting examples are ceramic micro heating elements or gear wheel/shaft samples which can be performed as fixed or movable combinations. Micro inmold-labelling using PIM feed-stocks offers further promising opportunities.

Abstract: Melt flow properties in micro cavity play an important role in the micro injection molding (MIM). Based on the point view of improving the melting plastification quality, this study focus on solving the problem of melt filling difficulty in micro cavity of MIM by introducing the ultrasonic vibration field into the polymer plastification process. This paper studied the polymer’s ultrasonic plasitfication process by Theoretical analysis and Polymer ultrasonic plastification experiment.

Abstract: The precision control of the injection process in micro injection molding demands precise tracking of the moment that melt front passes through the nozzle so that accurate prediction of the amount of melt being injected into the mould can be achieved. The tracking accuracy, to large extent, depends on the processing of pressure signals followed by the identification of the critical moment that melt front reaches the nozzle. A new adaptive Kalman filter was introduced in this study to calculate and predict the amount of melt injected. The filter eliminated the delay error and was more robust than other filters. The adaptive Kalman filter switches between two Qs for steadystate and transient estimations, allowing resetting of the Kalman gain so that convergence is speeded up in calculations. Experimental and simulation results prove the effectiveness of the method proposed.

Abstract: This research first indicates the melt front delay of wedge-shaped lightguiding plate of backlight module on micro injection molding. This research fabricated the patterns of mold insert of lightguiding plate by photo etching process. The micro-facture of lightguiding plate was manufactured by micro injection molding. The lightguiding plate of backlight module was used for the PMMA material. The single parameter method was used to discuss the flatness and replication properties for different processing parameters (mold temperature, melt temperature, packing pressure, packing time and injection pressure). The results show that there are melt front delays due to the slow injection velocity, the low temperature induced by the little effect of shear heating, the high viscosity, the large flow resistance and the slow flow velocity. The mold temperature is the most important factor for the flatness and the replication of micro-feature of liughtguiding plate. Lower mold temperature induces better flatness properties. The surface roughness of micro-facture of lightguiding plate is 8.8 nm on micro injection molding for this work.

Abstract: To overcome the lack of micro manufacturing processes suitable for medium and large scale production as well as to process high resistive materials a special variant of micro injection molding is currently under development: micro powder injection molding (MicroPIM), which already enables the manufacturing of finest detailed components with structure sizes down to a few ten micrometer. In order to expand the scope of application of MicroPIM, tests are being conducted with pure tungsten powders or tungsten alloy powders. As further improvement, micro twocomponent injection molding allows, for example, the fabrication of micro components consisting of two ceramic materials with different physical properties.

Abstract: Understanding the solid conveying process is important for the optimal design of micro injection molding machines. To solve problems such as starve feeding and process instability during plastication of polymers, which deteriorate product qualities, studies have been carried out on the conveying process of discrete polymer pellets. The effect of screw axis inclination on the speed of solid conveying is investigated with both simulation and experimental approaches. A discrete element modeling method (DEM) specially designed for simulating polymer particle movements in screw channels, which takes into account the effect of gravity while maintaining the simplicity of calculations, has been developed. The agreements between results of simulations and experiments verify the integrity of the models developed herein. The proposed modeling method is capable of optimizing the design of plasticizers of micro injection molding machines.

Abstract: In this work, we made micromolds using SU-8 photoresist and adopted electroless Ni-P deposition, well known as a hard coating material, to improve the rigidity and durability of SU-8 micromolds. After a micromold using SU-8 was defined by conventional lithography, Ni-P layer was electrolessly deposited on SU-8. By means of electroless Ni-P deposition, it was possible to increase the hardness of a micromold as much as about 17 times. In addition, it will be able to make various sized micromolds with one photomask by regulating the thickness of Ni-P layer.

Abstract: The purpose of this paper presents the optical properties of microstructure of lightguiding plate for micro injection molding (MIM) and micro injection-compression molding (MICM). The lightguiding plate is applied on LCD of two inch of digital camera. Its radius of microstructure is from 100μm to 300μm by linearity expansion. The material of lightguiding plate uses the PMMA plastic. This paper uses the luminance distribution to make a comparison between MIM and MICM for the optical properties of lightguiding plate. The important parameters of process for optical properties are the mold temperature, melt temperature and packing pressure in micro injection molding. The important parameters of process for optical properties are the compression distance, mold temperature and compression speed in micro injection-compression molding. The process of micro injection-compression molding is better than micro injection molding for optical properties.

Abstract: Analysis of the residual stress state, the microstructure and surface topography of ceramic microcomponents made of Y2O3-stabilized ZrO2 produced by micro powder injection moulding were performed. During the production of the microspecimens sintering conditions were varied. The measurement of residual stresses has been carried out using the MAXIM (MAterials XRay IMaging) diffractometer at HASYLAB beamline G3 at DESY in Hamburg (Germany). The microstructure and surface topography of differently moulded specimens were examined using a scanning electron microscope (SEM) and a confocal white light microscope type NANOFOCUS. The findings are used to establish correlations between process parameters and characteristics of the microcomponents. These will allow to improve the production process with respect to the mechanical properties of the microcomponents.