Tuesday, June 7, 2011

My Newest Baby Lives!

The main reason that I chose the graduate lab that I am in, is because we BUILD things here. Of course I spend a lot of time on the computer, and a decent amount on theory and modeling, but in the end - I get to MAKE things. Hello, machine shop. My personal therapy.

My Master's degree was spent designing, building, and testing a machine. I built a second machine sort of between Master's and PhD project, which was a improved and smaller version of the first machine, applied to a different manufacturing process.

And now, I have built a third machine as part of the "make it happen!" stage of the PhD. This third machine is basically a stamping machine. The stamping manufacturing process will go like this: I put a rubber stamp onto a spincoating chuck, squirt on some ink, spin the stamp to spread the ink into a thin even coating, and then I carefully press a substrate onto the stamp to transfer the inked pattern. I then heat up the substrate to evaporate any remaining liquid and make sure the pattern is dry.

The trick here is that the substrate has to be very precisely aligned with the stamp. To do this precise alignment, I used kinematic couplings and designed a flexure to control the movement of the substrate during the stamping process. I wrote about the fixturing and the flexure design on Engineer Blogs, so go check it out there.

The key takeaway is that the machine I designed looked like this in CAD:

And then I spent some time in the machine shop, and the machine in real life now looks like this:

Two weeks ago, I prepared to press the "On" button for the first time. I had my safety glasses on, and I stood for a good thirty seconds with my finger poised over the button, running through everything in my head to make sure I had everything hooked up properly.

Finally, with a deep breath, I took the plunge.

And nothing happened.

Now, actually, this is not the worst thing that could happen. Nothing blew up, so it's still a minor success. The base of this stamping machine is a spincoater, available commercially. But of course the warranty is completely voided, because the first thing I did was take it all apart. And in the process of putting it back together, because I am making so many modifications (taking off the fairing and the bowl, adding an internal valve to change the vacuum chuck to a positive pressure chuck, changing to air purge instead of N2 purge, etc.), I had to short out all the safety interlocks.

So it's not at all unreasonable that something might blow up upon applying power for the first time.

(Actually one would think I should have turned this on and tested it BEFORE I took it apart... but where is the fun in that?)

Upon consulting the owner's manual, I discovered that the machine will not power on until sufficient vacuum and purge pressures are applied. So I proceeded to hook up the required inputs.

(Actually one would think I should have read the owner's manual first, but again, the fun? where is it?)

Then, not expecting much, I tried hitting the On switch again. Instant power! Lights started flashing, I could hear the pump running, and a faint hiss where I hadn't sealed a fitting well enough. Gees. I didn't even have my safety glasses on... and I didn't get to do any build-up or suspenseful pause, or anything!  Oh well, it turned on, fanfare or no. :) With that progress, I called it a day, and went home for dinner.

And by last week, I had the machine not only turning on, but programmed with recipes, a homing routine, manual internal valves, and a vacuum chuck on the substrate side. My presentation at my weekly progress meeting with my advisor last week was one small square of glass stamped (badly, at that) with green food coloring.

It's not much to look at, but this means that my PhD stamping machine is designed, fabricated, assembled, and capable of running experiments.

So I'm pleased to report, my baby lives!

No comments:

Post a Comment