High resolution micro ultrasonic machining for trimming 3D microstructures

Abstract

This paper reports on the evaluation of a high resolution micro ultrasonic machining (HR-μUSM) process suitable for post fabrication trimming of complex 3D microstructures made from fused silica. Unlike conventional USM, the HR-μUSM process aims for low machining rates, providing high resolution and high surface quality. The machining rate is reduced by keeping the micro-tool tip at a fixed distance from the workpiece and vibrating it at a small amplitude. The surface roughness is improved by an appropriate selection of abrasive particles. Fluidic modeling is performed to study interaction among the vibrating micro-tool tip, workpiece, and the slurry. Using 304 stainless steel (SS304) tool tips of 50 μm diameter, the machining performance of the HR-μUSM process is characterized on flat fused silica substrates. The depths and surface finish of machined features are evaluated as functions of slurry concentrations, separation between the micro-tool and workpiece, and machining time. Under the selected conditions, the HR-μUSM process achieves machining rates as low as 10 nm s −1 averaged over the first minute of machining of a flat virgin sample. This corresponds to a mass removal rate of ≈20 ng min −1. The average surface roughness, S a , achieved is as low as 30 nm. Analytical and numerical modeling are used to explain the typical profile of the machined features as well as machining rates. The process is used to demonstrate trimming of hemispherical 3D shells made of fused silica.

Discharge current effect on machining characteristics and mechanical properties of aluminum alloy 6061 workpiece produced by electric discharging machining process

“…With the development of high-precision technology, more and more high-strength, high-hardness, and hightemperature materials are needed. A number of material removal processes such as electrical discharge machining (EDM), [1][2][3] electrical ultrasonic machining (USM), 4,5 electrochemical machining (ECM), 6,7 and laser beam machining (LBM) [8][9][10] are developed for better ways of machining complex shapes in these highstrength materials.…”

Batch Mode Microultrasonic Machining (<inline-formula> <tex-math notation="LaTeX">$\boldsymbol \mu $ </tex-math></inline-formula>USM) Using Workpiece Vibration

“…Stainless steel tools have a lower tool wear ratio, i.e. the ratio of the tool height worn to the machined depth [2], [6]. For this letter, the µUSM tools were fabricated by micro electro discharge machining (µEDM) of a 500-µm thick stainless steel (SS#304) plate.…”

“…These ceramic materials are mostly transparent, insulating, and brittle and are not well suited for machining by laser, electrodischarge machining (EDM), or micromilling/drilling. The µUSM process is appropriate for micromachining both planar and 3-D structures of brittle materials without inducing stress or subsurface cracks [1]- [6]. Batch mode µUSM, which is performed with a patterned planar tool, facilitates die-scale or wafer-scale transfer of complicated lithographical patterns onto ceramic substrates with high throughput [2].…”

A Novel Mechanical Frequency Tuning Method Based on Mass-Stiffness Decoupling for MEMS Gyroscopes

“…Moreover, a directional lapping technique can decrease the frequency split well but it is complicated to determine the position of the rigid-axis [ 6 ]. Although adding mass has little effect on the quality factor, it requires high-precision equipment and is high-cost, which creates many difficulties for frequency tuning [ 7 , 8 , 9 ].…”