Micromachining has been increasingly used to manufacture high-tech micro- and miniature-scale devices from a variety of materials for many applications. Realizing significant advances in the quality and productivity of micromachining processes is vital to transform micromachining into an industrially-viable process. Thus, fundamental knowledge on process and system characteristics are urgently needed. Since micromachining forces embody and manifest critical information on the mechanics, dynamics, stability, and health of the micromachining processes and systems, accurate measurement of those forces is paramount to gaining fundamental understanding on, and thus, to realize transformative advances in, micromachining science and engineering. The state-of-the-art force measurement systems are incapable of measuring micromachining forces accurately, thereby hindering further advancements. This award supports scientific and technological investigations on accurate measurement of three-dimensional micromachining forces. The research will create a unique dynamic modeling approach to inform next-generation dynamometer designs. They will facilitate tremendous advances in the capability to manufacture a myriad of micro- and miniature-scale devices for many fields, including medical/biomedical, aerospace, military/defense, and consumer products.
The research objectives of this project are (1) to understand the relationship between structural dynamics and force measurement characteristics of dynamometers; (2) to create compensation approaches to significantly expand three-dimensional measurement bandwidth; and (3) to construct/validate models to enable future dynamometer designs. To achieve Objective 1, experimental modal analyses will be conducted on commercial miniature machining dynamometers. The dynamic excitation will be provided using a custom impact excitation system, and the dynamic response will be measured using laser Doppler vibrometery. Both the excitation (from the impact system) and the forces from the dynamometer will be collected and compared. Different boundary conditions (solid, elastic) will be considered. From these tests, both the receptance and force-to-force frequency response functions will be obtained within the 0-60 kHz bandwidth. Towards Objective 2, inverse-filtering techniques will be used to devise a compensation approach to expand the measurement bandwidth by at least 20 folds. Both experimental validation and functional evaluation (using micromilling and microdrilling processes) of the developed compensation approach will be performed. For Objective 3, structural-dynamics models of the dynamometer structure, including different boundary conditions and workpiece dynamics, will be developed using the spectral-Tchebychev technique. These models will also be experimentally validated using the same experimental modal analysis techniques as those for achieving Objective 1.