The purpose of this research project is to improve the capability of the laser micromachinning process, so that any desired 3D surface can be produced by taking the 3D information from a CAD system and automatically generating the NC part programs. In addition, surface quality should be able to be controlled by specifying optimised parameters. This paper presents the algorithms and a software system, which processes 3D geometry in an STL file format from a CAD system and produces the NC part program to mill the surface using the Excimer laser ablation process. Simple structures are used to demonstrate the prototype system's part programming capabilities, and an actual surface is machined.

A prototyping and microfabrication CAD/CAM tool for the excimer laser micromachining process.

In this paper a novel technique, referred to as a vector setting in the aerospace industry, is reported which has been developed for positioning and orienting drilling bushes on curved surfaces. The position and orientation of holes and their axis in parts and tooling in the aerospace industry must conform to strict tolerances, however, the process of locating and orienting the bushes in drilling plates having curved surfaces is slow and time consuming. This is because the existing process used is a trial and error one, and past research in automated drilling in the aerospace industry has not covered this area. A prototype device has been developed which reduces the setting time. The device has two angular adjustments, which are computed using software specially written for this purpose. The device is used in conjunction with a 3D spatial measurement system in order to determine reference points on the part or tooling and the device. Experimental results on a prototype indicate a substantial time saving as well as good accuracy in orienting the drill axis at a given point on a surface.

MEMS CAD tools have been developed for conventional micromachining processes, however, the simulation of the mask projection Excimer laser process has not been researched. This paper describes the development of a 3D visualization software for simulating micromachining of 3D microstructures using an Excimer laser system. Currently, the surface produced by a program manually written for an Excimer laser is not predictable, except for simple cases, and the surface has to be machined to verify the program. Therefore, a desired surface geometry is achieved by a trial and error process. The visualization software described uses a standard parametric solid modelling CAD system to simulate the micromachining process by transforming the program data into 2D color-coded depth map and a 3D surface. This increases the number of surfaces that can be investigated, making it appropriate for studies of the resulting surface texture on the 3D structure formed. The machining path and ablation rate can be controlled, and because ofthe universality ofthe software routines, the simulator is applicable to different shaped masks. Several examples of 3D simulated surfaces are presented using a rectangular shaped mask, and a comparison is made with actual machined surfaces.

A 3D CAM tool for rapid prototyping and small-scale production of MEMS devices based on excimer laser ablation process has been developed. The system's algorithms use the 3D geometry of a microstructure, defined in a CAD model, and parameters that influence the process (etch rate, wall angle, stitching errors, etc.) to automatically generate a precise NC part program for the excimer laser machine.The performance of the system has been verified by NC part program generation for several 3D microstructures and subsequent machining trials. Stitching errors of 23.4±2.2 lm wide and 3.4±1.5 lm height were observed when overlap size between adjacent volumes were zero, when ablating 100·100 lm features in PC at fluence of 0.9 J/cm 2 using a workpiece dragging technique.When the size of the overlap was optimised by software based on optimal process parameters determined by Taguchi design of experiment method (DOE) and incorporated in the mask design the maximum stitching errors are reduced to 13.4±2.2 lm wide and 1.4±0.9 lm in height under the same conditions. Employing the hexagonal shaped mask with incorporated size of the image overlap, horizontal-stitching errors with width of 2.4±0.2 lm wide and 1.4±0.2 lm high were observed.The software simplifies part program creation and is useful for excimer laser operators who currently use a tedious trial and error process to generate microstructure parts.