Vibration-Assisted Machining for Microsystems

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Abstract

Supporting Materials

Abstract

The Ultramill EVAM tool is used to machine MEMS scale features with complex 3-D geometry. A procedure is developed to establish the toolpath needed to produce a desired surface, using the morphological operation “dilation” to determine the required tool center offset given the tool cutting edge profile and the dimensions of the elliptical vibratory motion. Test parts are machined using tools with both round-nose and sharp-nose geometry. The parts made with round-nosed tools have sculpted 3-D and non-orthogonal planar features. These features are up to 20 µm tall, whereas parts previously made by EVAM had heights of less than 1 µm. Because round-nosed tools can only make low aspect-ratio structures with shallow curved sidewalls, sharp-nosed tools are tested as a way to overcome these limitations. Relative motion between a sharp-nose tool's cutting edge and the workpiece is found to result in non-orthogonal cutting, whereas round nosed tools can be modeled by orthogonal cutting. Sharp-nose tools are used to make two types of part: 80 µm tall trihedrons and small (< 15 µm wide) groove structures featuring sculpted 3-D geometry with an aspect ratio of 0.3. Suggestions for improving sharpnose tool geometry are developed based on examination of these test parts. Tool wear results are presented for sharp nose tools used to machine stainless steel. Thermal expansion of the Ultramill, which can cause form error in parts, is measured and found to be partially caused by expansion of the base block upon which the piezoelectric actuators rest.

Supporting Materials

Micro-structure Fabrication Using Elliptical Vibration-assisted Machining (EVAM) , (1860K PDF)

Micro-machining Using EVAM (329K PDF)

The following faculty, students, and PEC affiliates are involved in this project: