Fabrication of a 3D structure and surface texture using excimer laser mask
projection ablation processes typically requires the machine operator to develop a specific
NC part program for the desired structure geometry, and also incorporate appropriate
machine parameters to achieve the desired surface finish. The capability of the laser
ablation process could therefore be significantly improved by developing a CAD/CAM
system that automatically generates the NC part program using the 3D information of the
CAD model of the desired structure. Accordingly, the focus of this research was to
develop such a system that is, an effective CAD/CAM system specifically for excimer
laser mask projection micromachining tools.
To meet these requirements, a unique combination of commercially available
systems was used to develop the new CAD/CAM system. The systems used comprised of
a computer aided, feature based parametric design system (SolidWorks), together with
its extended programming capabilities based on Automated Programming Interface (API)
functions for Windows applications, and Visual Basic (VB) 6.0 programming utilities.
The system's algorithms use a novel methodology to extract the 3D geometry of a
microstructure. Two different techniques have been developed to extract the 3D data.
First, where 3D geometry information from a CAD model was defined as a Stereolithography
(STL) file, and second, where this information has been contained in a set of
bit-map (BMP) files that represent a sliced or layered structure of a CAD model. Based
on this, first an algorithm to create NC part programs to support Step-and-repeat
micromachining technique was developed and then successfully extended to be applicable
for another commonly used micromachining method, Workpiece-Dragging technique.
The systems algorithms for both techniques are based on the raster-colour
programming technique, resulting in substantially reduced mathematical complexity and
computational time. This is the first time this approach has been used to support direct
conversion of 3D geometry from a CAD model into an NC part program compatible with
the excimer laser CNC controller. 2D mathematical models for controlling edge and
stitching errors were also implemented in the system.
An additional technique, named as 'Common Nest' has been developed with the
aim to enable automatic NC part programming when microstructure design to be
completed successfully, requires use of multiple complex mask patterns as a projection
tool instead of just a single square aperture.
The effectiveness of the system was verified by NC part program generation for
several 3D microstructures and subsequent machining trials using polycarbonate (PC) and
Polyethylene terephthalate (PET), and optimised processing parameters. Excellent
agreement was obtained between the laser machined geometries and the microstructure
CAD models. The Laser Scanning Confocal Microscope (LSCM) measured the lateral
dimensions tolerance of 2m.
The system was also successfully applied for a practical micro-engineering
application, for the development of a microfluidics cell transportation device.
| Identifer | oai:union.ndltd.org:ADTP/216610 |
| Date | January 2006 |
| Creators | Mutapcic, Emir, n/a |
| Publisher | Swinburne University of Technology. Faculty of Engineering and Industrial Sciences |
| Source Sets | Australiasian Digital Theses Program |
| Language | English |
| Detected Language | English |
| Rights | http://www.swin.edu.au/), Copyright Emir Mutapcic |
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