An experimental investigation of micro-channels on transparent material using Nd: YAG laser transmission technique

Abstract

Among the fastest growing basic materials, polymers have good strength-to-weight ratios, easy to shape, relatively economical, and recyclable which enabled it to become substitutes for metals and alloys in the fields of medical, automobile, aerospace, electronics, thermal and chemical engineering. But a thick transparent PMMA plate creates deep sub-surface cracks due to the burning and charring of polymeric chains, making the operation with Nd: YAG laser radiation extremely difficult. In the current research, a 75 W nanosecond pulsed Nd: YAG laser system is applied to make micro-channel with adequate depth on a thick transparent PMMA plate by using transmission cutting technique. The input process factors considered are pulse width, laser power, cutting speed, and pulse frequency in order to examine the quality characteristics, the depth of cut and heat affected zone (HAZ) in and around the formed micro-channel. To design the experiment of laser transmission channelling of thick PMMA plate of 11 mm, a central composite design (CCD) methodology is used. Due to open-air laser processing, undesirable laser processing effects have been minimised, resulting in a finer and cleaner micro-channel structure with adequate depth of cut, kerf width and minimal Heat Affected Zone (HAZ) width with laser power of around 9 W, pulse frequency of around 33 kHz and cutting speed of 2 mm/sec.