HOLE DRILLING CAPABILITIES USING AN ULTRAFAST VARIABLE PULSE DURATION LASER IN COMBINATION WITH A MULTI-AXIS SCANNER: Paper # Micro 1204

摘要

TRUMPF has a novel compressor design which maintains beam pointing while tuning the laser's pulse duration. With our prototype system, we can tune the pulse duration between <400 fs and 24 ps in only 300 ms. This allows for rapid pulse duration changes during materials processing. Previous work has shown that while 1 ps and shorter pulse durations give superior material removal rates in stainless steel, it can come at the expense of reduced surface quality such as the appearance of micropits and cone like protrusions. In contrast, longer pulse durations have lower material removal rates but decreased tendencies for surface defects. SCANLAB has a highly integrated 5-axis scanning system, the precSYS. This scanner allows for dynamic control of angle of incidence, focus position, and spiral tightness. In addition, rotation frequencies up to 500 Hz on diameters ≤ 1 mm are achieved. Most material interaction studies examining the impact of pulse duration have concentrated upon volume removal on sheet stock. Here, the laser is normally scanned in a square or rectangular pattern, and the depth and surface finish of the pocket is examined. With the ability to tune the pulse duration without beam drift, we can explore processes where fine alignment is required. Here, we examine hole drilling with different pulse durations and scanner settings. We present data on hole machining efficacy, hole shape control, sidewall profile, and roughness.