Drilling of CFRP with Reduced and Non-Directional Heat-Affected Zone by Using 3-kW CW Single-Mode Fiber Laser

High-precision drilling of carbon fiber reinforced plastic (CFRP) using a 3-kW continuous-wave (CW) single-mode fiber laser has been demonstrated. Holes with a diameter of 6.4 mm have been successfully drilled on a 2-mm-thick thermoset CFRP. The laser was scanned at a scanning speed of 10 m/s with a galvanometer scanner by a multi-pass method with a time interval of 20 ms. The processing time was 2.7 seconds, which was equivalent to that in mechanical processing. By optimizing the conditions of scanning and gas injection, the width of heat-affected zone (HAZ) was controlled to about 100 mu m. Although a HAZ tends to expand in the direction of carbon the fibers, the zone was well-controlled in all directions. The results show the potential of the high-power CW single-mode fiber laser for the application to high speed and high quality drilling of CFRP.