Papers by Keyword: Micro-Features

Abstract: The method of using microwelding machine to fabricate micro features on a stainless steel micro mould has been studied. The micro features obtained from molding using an ultrasonic microwelding machine have shown distinctive characteristics. The microflow behavior of polymer melt during the microwelding process is also studied. The micro molds of 0.2mm thick and through holes of 0.05mm and 0.2mm in diameters were used. Results show micro features can be produced using the microwelding machine with molding speed comparable to that of micro injection molding.

Abstract: The method of using ultrasonic heating to aid high precision moulding of micro features has been studies. The study developed a method of using ultrasonic vibration to heat the polymer and hot embossing high precision micro features. A commercial ultrasonic welding machine is converted to provide the heating of polymer and mold then into precision micro features for study of ultrasonic heating and the microflow of polymer under ultrasonic agitation. A stainless steel microporous mold of 200µm thick with through holes of 50µm and 200µm in diameter were used. Using a frequency of 35kHz, the microflow behavior of PC (Polycarbonate) and PE (Polyethylene) in the microchannels were investigated. The differing properties of microflow for these two types of polymer give indication on the theoretical and practical agreement on prediction of microflow under ultrasonic energy.

Abstract: This study demonstrates the replication property and surface roughness for metal micro-mold that combines the replica molding (REM) and electroforming techniques. The micro-mold firstly uses the silicon wafer to fabricate the master mold by UV-LIGA method, and then uses the sputtering method to sputter the Ni element as the seed layer on the surface of master mold. The electroforming method manufactures the Ni mold insert from the master mold with seed layer. Finally, this study uses the PDMS material to replicate the micro-feature from the Ni mold insert by replica molding. This study indicates the replication property and surface roughness of different micro-feature shapes and sizes (concave and convex) for Ni mold insert and molded PDMS.

Abstract: This study succeeds to replicate a micro-feature by ultrasonic nanoimprint. The conjunction effect of the pressure and the ultrasonic vibration enables flowing of plastic into a more precise micro-feature of the metal mold. The longitudinal wave generated by an ultrasonic system of the frequency 35KMz and output power 900W. The micro-feature of the Ni mold insert used in the experiment is a groove shape. The groove’s width is 49 µm and its depth is 25 µm. The PMMA, PC and PP are chosen with the replication materials. This study also discusses the replication properties of plastic film by different processing parameters (delay pressure, fusion pressure, embossing pressure, delay time, fusion time and embossing time).

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: A workpiece with a large surface area is likely to be uneven due to form error and waviness. These geometric disturbances can cause inaccurate micro shapes to be formed when micro features are micro-grooved into the surface and cause the resulting workpiece to fail to function as desired. Thus, the real-time monitoring and compensation is required to guarantee the form accuracy of micro features while machining the workpiece with a large surface area. In this study, a method is suggested for real-time measurement and compensation of geometric errors for the micro grooving of a large flat surface using a laser displacement sensor placed ahead of the cutting tool. Experimental results show that the compensated surface profiles fit the measured ones within an allowable tolerance even at cutting speeds as high as 200 mm/s.