CO2 Laser Micromachining of Acrylic Sheets to Increase Their Thermal Insulation

Abstract

In this work, electro-pneumatically operated x-y table was fully designed, installed, tested and operated in order to micro-machine coloured acrylic sheets to increase thermal insulation. The x-y table had been designed and installed to give a longitudinal distance of 100mm, with variable speed from 500 mm/s down to nearly 21% of it. The lateral electrically operated part of the table was designed to give a step of 1mm down to 47μm distance along the overall lateral distance of 50mm. The table was used to move Polymethylmetacrylate, PMMA, sheets of 100 x 100 x 2mm under irradiation of CO2 laser to engrave micro-channels resemble blackbody cavities. Five colours of PMMA were chosen for this purpose, namely red, green, blue, black and white sheets, RGBKW. Laser power 30, 25, 20 and 15 Watts, beside 1, 2, 3 and 4 laser passes were also chosen to give a combinations of 35 samples different in parameters. When thermal infrared radiation enter these micro-channels they will undergo multiple reflections and re-emission losing some of their energy and resulted in reduction of the transmitted thermal radiation crossing the channels. Experimental results showed temperature reduction between micro-machined and standard samples of PMMA, when using different colours, laser powers and laser passes, which fulfilled the state of increased thermal insulation of acrylic sheets when laser micro-machined, and consequently fulfill the purpose of this research.