FABRICATION OF HIGH ASPECT RATIO MICROCHANNELS ON BOROSILICATE GLASS USING MICRO-USM PROCESS

Abstract

Micro-USM has many applications, especially in machining hard and brittle materials like glass, silicon, zirconia, and titanium. These machined components find their applications in various science and engineering fields. Microchannels are a term that is common in the microdomain. The first microchannels were fabricated using chemical etching and lithography. After realizing the potential of micro-USM for the fabrication of micro-products, it was successfully employed to manufacture microchannels on materials like glass and silicon. However, limitations like tool wear and debris accumulation in the machining gap tend to hamper the geometrical capabilities of micro-USM, especially when machining at higher depths. In order to mitigate these effects, variations of micro USM like rotary tool micro-USM and electrophoresis assistance have been developed. This study analyzes the geometrical capabilities, depth of channel (DOC), the width of the channel (WOC), stray cut, form accuracy, and surface roughness of the fabricated microchannels. In the current experimentation, a microchannel of maximum depth of 605.65µm and reasonable form accuracy was obtained without the help of other assistances like chemical, rotary tool, or electro rheological processing. A series of rectangular cross-sectioned microchannels of depths varying from 120µm to 600µm were fabricated on borosilicate glass using the micro-USM process. However, the preferred cross-section of microchannels, which is rectangular, could not be obtained due to the tool wear and debris accumulation in the machining zone. The stray cut was an inevitable phenomenon associated with micro-USM, which can be related to the velocity of abrasives in the slurry medium. All the geometrical parameters were also compared at various power ratings to identify the setting which could provide microchannels with appreciable dimensions. Similarly, the microchannels fabricated at the three different power ratings were also analyzed to understand the effect of power rating on the surface finish. Microchannels fabricated at a lower power rating exhibited the best surface roughness. As the depth of the microchannels increases, the surface finish deteriorates. Numerous plastically deformed grooves were observed in the SEM images of the microchannels, indicating the repeated indentations of trapped abrasives and debris at higher depths.