 about the hole size and geometry, then they can check it less.”
The latest capabilities enable users to drill production parts to air-flow tolerances of ±3% on parts with thermal barrier coating (TBC) or ±1% on simple metallic parts, Barry said.
Micro Drilling for Medical
Laser micromachining in medical or microelectronics applications often uses short-pulse fiber laser markers for drilling holes in applications including wafers, medical cannulae and microchannels for fluids, noted Mark L. Boyle, laser product engineer, Miyachi Unitek Corp. (Monrovia, CA).
A laser systems integrator, Miyachi Unitek integrates 1070-nm, pulsed fiber lasers into complete laser systems for drilling holes in metals and other materials for a range of different applications. “We also have the vanadate green and vanadate UV technologies, for plastics and for some metals, and also the picosecond lasers,” Boyle said. “We’re running the whole gamut of IR to UV and nanosecond to picosecond lasers, but metal processing with fiber lasers is really where we’ve been focused.
With short-pulse lasers, users can get very fine precision and very clean walls, Boyle noted. “It’s all dependent on what the user requires. What we find is for most applications, most people are fine with the results from an IR laser. Now and then they’ll have stiffer requirements on the edge quality of those holes. As you go smaller and smaller, into the hundreds of microns, to sub-hundred micron, everything becomes a lot more critical because you don’t want any melt around it, you don’t want it to re-form and grow back over the hole.”
Picosecond lasers offer the advantage of virtually no HAZ for holemaking operations, Boyle said. “Particularly from the picosecond lasers, those are no HAZ or very little HAZ. When you get to the nanosecond lasers, particularly the IR has a little bit more, but in some cases, you can still get a very good edge quality.”
These picosecond lasers have applications drilling metals, stainless, and aluminum, Boyle said, to about a 10-µm typical hole 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 per