One Stop Micro

A long time back, a senior colleague of mine introduced me to the phrase “Superstitious Pigeons”. I will describe the real thing before I relate it to laser micromachining.

There was this psychologist named Skinner at Harvard in the 1950s, and he conducted some experiments with pigeons to study how superstitions developed. He put some really hungry pigeons in a cage, with an automatic timed food dispenser. The timing was independent of what the pigeons ate or did- food would pop out every so many minutes.

The pigeons of course didn’t know the auto-timing part, them being bird-brained and all that. They associated the delivery of food with whatever action they were performing at that instant. Lets say Pigeon #1 was singing an Elvis song (this was the 1950s, mind you) and food popped out just when he started singing the song, he thought Elvis was delivering the food. So, he would sing the same Elvis song whenever he wanted food. Even if the food never appeared after numerous attempts, he wouldn’t give up. That is, Mr. Pigeon got superstitious. And this kept getting even more strongly re-enforced in the face of repeated failures. Wouldn’t you say there is a subtle difference between superstition and perseverance? Hmmm, may be a gray area separates the two.

So, what does this have to do with laser micromachining? Very often, customers send exotic materials or composites to be machined. To get good cut quality, there are numerous parameters that can be (or need to be) adjusted. The list includes: focal length of the final lens, laser energy, spot-size, machining rate, pulse-overlap, ambient gas, pulse-energy, average energy… Many of these are inter-related.

An inexperienced machinist might change multiple parameters at the same time, and after numerous attempts and a multitude of parameter-sets, would start to see what he believes to be a pattern of good machining. But he never is able to refine it and narrow it down. Of course, he never gives up too. He has a coffee break every hour, comes back fresh, believing intently that a particular parameter is the answer. By evening, he has tried so many processing parameters, and starts believing intently that he can solve this thing today. His faith in his ability to solve this problem has gotten stronger. He becomes more persevering, and has a book full of test results.

His manager, meanwhile, is distraught. Not at the micromachinist’s plight, but because of repeated promises that the solution is at hand. An experienced manager will, by now, realize that machinist has lost it, has become superstitious. Time to bring in the big honcho.

The senior guy has gone through the drill numerous times over the last many years. He calmly selects 3 parameters to change, changes them one at a time, and arrives at the solution in an hour. There you have it- the difference between a rational person and a superstitious person. Or pigeons.

Experience matters.