I'm considering buying an IH mill for prototyping in mostly plastic and aluminum. To help pay for it, I might be able to get some work doing various production runs in plastic for a company I know. The issue is the tolerance is really, really tight.
The production run consists of 300 to 500 parts in acrylic plastic. Dimensions are .3" wide x .160" tall and range from 2" to 6" long. Down the length of the part is a groove. The groove is 0.072" wide by 0.036" deep. I've attached a very ROUGH sketch.
Tolerance required. This is the TRICKY part. The drawing calls out standard tolerances, but IP (Inspection Protocol) is ridiculous and holds much tighter tolerances.
The actual 0.3" wide has to be between 0.299 and 0.297 so that it can 'easily' slide into a tool holder for production. If it's a tight fit, or too lose, it's rejected.
The 0.160" height has to be slightly undersized between 0.1595" to 0.158", again to fit into the tool holder. This is where issues come in because two parts are placed together and if they're too tall or short, the total (0.160+0.160 = 0.320") dimension issue is magnified.
Lastly, looking at the groove, it needs to be .036 to 035 deep or it won't do it's job correctly.
These are currently made on an older 199x FADAL VMC. It's done by using a larger piece of acrylic, approx 14" x 9" (guessing on this one) and double sided sticky taping it to a plate mounted to the table, and cut as many as we can depending on the 2" to 6" length. We cut down to the tape and then 'pop' the parts out when finished and clean up.
My question is - can I make this part repeatably on an IH CNC setup? I've read in http://www.cnczone.com/forums/showpo...7&postcount=52 that ksanalytical thinks he can do better than +-0.001 in the Z. Based on that thread, it's a matter of spending the time to make sure I setup the machine correctly. Any thoughts?
Thanks in advance,
Mark