الفهرس Only 14 pages are availabe for public view
 |  | from | 81 |  |  |
| | | from | 81 | | |
Abstract
CO2-Iaser is one of the techniques that serve manufacturing of micro-products. Given that a source of light can be concentrated to produce a small spot of intense heat energy, the use. of lasers for putting can offer many advantages including; minimal part distortion absence of tool wear, cutting materials regardless of their hardness and unlimited profile machining capability. Lasers have many applications in industry like; shock hardening, micromachining, drilling/cutting, glazing, welding, cladding alloying and transformation hardening. The areas of applications include diesel injector drilling, inkjet nozzles drilling, surface cleaning of art, writing gratings, orifice drilling and optical circuits.
The objective of this study is a theoretical and empirical study of some quality aspects associated with microdrilling of acrylic material using CO2-laser. The main goals include’ quantitative understanding of the process, parametric optimization of laser machining process and using experimental (empirical) models to reveal the physical processes in depth and detail.
The test sample comprises round holes, squared holes, rectangular slots and circular slots. Three values (levels) of size were machined 140,210 and 280?m.
The considered parameters are classified mainly into process parameters and material parameters. The process parameters related directly to the machining process and controlled in the study are variable parameters such as; laser average power (P, W), head traverse speed (S, m/s), laser feed rate (FR, dpi) and laser pulse rate (PR, ppi). Material parameters include the material type and sheet thickness (T, mm). Other process parameters such as; laser wave length (?, ?m), focal length of lens used (F, ?m). depth of focus (DOF. ~m) and optical mechanism were kept constant during the study.
In order to assess and analyze the quality of micromachined parts, an image-processing technique was applied for measuring the dimensions, geometry, and profile of microdrilled holes. A calibrated CCD camera was used to capture a microscopic image of the inspected object. An image-processing package was used for the analysis and evaluation of the captured images. A least squares method (LSM) was applied to evaluate the diameter and roundness error of the drilled holes using the data colleted from the captured image.