ole tolerance, and laser drilling to 20–150 µm on drilling of surgical needles. “We’ve done some ceramics and some silicon, all with IR and it’s just a question of what are the requirements for that hole? How clean does it have to be? What are the requirements of debris coming off? How to handle that debris that’s coming off?”
Drilling techniques can be either stationary, with percussion drilling, or employing the trepanning method, moving the laser in concentric circles, Boyle said. “In trepanning drilling, we are using the galvonometric scanning head, mapping out an X-Y plane, marking at about an inch to five inches a second.”
Picosecond Laser Prices Falling
After starting out cost-prohibitive, picosecond lasers’ costs have fallen and these lasers have emerged as viable manufacturing solutions, noted Sascha Weiler, program manager, microprocessing applications, Trumpf Inc. (Farmington, CT). The company’s TruMicro series 5000 picosecond laser systems excel at hole drilling in injection nozzles for automotive and turbine blades for aerospace applications. The TruMicro 5000 short-pulse lasers offer pulse durations under 10 ps, as well as one model rated at 800 femtosecond (fs) pulse duration.
“Picosecond lasers have come quite a way down in costs,” Weiler said. “On the high-quality side, if you use picoseconds, there it’s really more ablation. You get the highest quality on 100-µm holes, and you need that on injection nozzles. It competes with EDM, not only in quality, accuracy and time, but also on price. The cost per part is incredibly low.”
An advantage in drilling with these lasers is the quality offered by ablation, with virtually no HAZ. “It’s more or less direct vaporization,” Weiler said. “In the real world, there’s always a little heat, but with picosecond lasers, there is very little HAZ.”
Drilling strategies vary, but Weiler said percussion drilling makes sense when the aspect ratio is low, say with a 300-µm hole and material that is 300-µm thick. “If it’s a 1:10 aspect ratio, it’s not possible with percussion drilling,” he said. “With trepanning, you move the laser, and it’s like you’re steering inside of the hole. In addition, you can do the so-called helical drilling, which allows you to make undercuts.” ME
This article was first published in the November 2013 edition of Manufacturing Engineering magazine. Click here for PDF.
Published Date : 11/1/2013