Laser-Induced Plasma Micro-Machining (LIP-MM)

Northwestern University, Evanston IL

Investigators

Abstract

The objective of this research project is the conception of a new micromanufacturing process that emulates the material removal mechanisms that characterize micro electro-discharge machining. It will not require the use of electrodes and will not be limited to conductive materials only. The process will use ultra-short laser pulses focused in a dielectric slightly above the workpiece surface - instead of electric discharges between an electrode and a conductive workpiece - to create plasma whose explosive expansion facilitates material removal. The work will involve a substantial experimental component focused on the physical realization of the process. In addition, process characterization will be performed through the use of embedded micro-sensors to measure the temperature and stresses just below the source of the shock waves created by the plasma. The theoretical work will focus on the modeling and control of plasma properties and on the investigation of the physical principles that govern the laser-induced plasma-assisted process with emphasis on plasma-matter interaction and the material removal mechanisms. The new processes will offer unique capabilities not achievable by other currently existing competing methods for the manufacture of micro-scale components and features with high relative accuracy and complex geometries in a wide range of engineering materials. It will also entirely circumvent problems and costs associated with tool manufacture, wear and compensation in micro electro-discharge machining and the complexities of conventional laser processing. Real time process monitoring of the newly developed process through the use of embedded micro-sensors will offer an unprecedented instantaneous insight into the thermal and mechanical responses of the material during processing. This monitoring technique, once successfully realized, will also be applicable to other micro- as well as macro-scale process monitoring tasks.