Ultra-fast laser micromachining has been getting a lot of press lately; does it live up to its billing? In my view, ultra-fast micromachining has terrific potential, but I’d like to temper the enthusiasm with a little dose of reality. Amada Miyachi America has a new micromachining applications laboratory set up with a variety of different ultra-fast laser micromachining sources and motion platforms, so I am in a perfect position to show some examples of what ultra-fast laser micromachining can do from a laser independent systems integrator perspective
I’ll begin with one, big caveat: you must first match the laser source to your particular application, considering both performance and budget. Ultra-fast lasers offer unique micromachining capability, but they are not inexpensive, so it pays to do your homework to determine whether the benefits the laser provides to your specific process are justifiable via direct return on investment (ROI), or because it can provide unique features for a specific part. When considering the ROI for ultra-fast lasers, it is most important to factor in the reduction of post processing steps, including cleaning and de-burring, both mechanically and chemically. Refer to the recent blog "Cutting with femtosecond disk laser - ROI in less than a year" for more information.
What is micromachining – and how fast is ultra-fast?
Micromachining has some very specific processing requirements, chief among which are quality, dimensional accuracy, debris management, and the thermal impact of the process on the part. The actual definition of micromachining is somewhat vague. In general terms, it usually means creating feature sizes of 1 millimeter (mm) or smaller in materials that are 1mm thick or even thinner. The micromachining umbrella includes cutting, drilling, scribing, ablation, and texturing processes, each of which requires material removal.
The laser is a great micromachining tool – it offers the benefits of a non-contact “tool-less” process, optical spot sizes less than 10 microns, and extreme control on how much material is removed, down tothe micron level. Micromachining processes use lasers that operate in “pulsed mode,” so the optical energy is delivered to the material by discrete pulses that have a certain time duration, frequency (repetition rate) and power level.
The term “ultra-fast” does not refer to how quickly the laser processes, but rather to the pulse duration of the laser. For many years, lasers with pulse durations in the nanoseconds (ns) (10-9s, or one billionth of a second) were used, which provided a certain level of processing. Now, we’ve graduated to ultra-fast or ultra-short pulse lasers, with pulse durations measured in picoseconds (ps) (10-12s, or a thousandth of a nanosecond) and femtoseconds (fs) (10-15s, or a millionth of a nanosecond). Now we are really talking short (or fast). These shorter pulse widths fundamentally alter how the laser interacts with the material, offering some really significant benefits for some applications, as summarized in Table 1.
Ultra-fast lasers are definitely worth a look to see if they might work in your micromachining process. For a start, take a look at a few examples of what ultra-fast laser micromachining can accomplish. Note, these images show the laser-finished part from the machine with no post processing apart from an ultrasonic bath clean!