Checking Weight For Spc Pass/fail

[Kirby K.]

I've come upon an idea to check identical machined parts by weight to ensure that there are no missed operations (like deburring, broaching, counter bores, etc). I found that each operation removes a repeatable amount of material to a tenth of a gram. Each part is checked for height, out of square, OD and bore by a SPC program ran on a computer that is interfaced to the lathe (GE 18i T control) to make offsets. I would like to add another configuration to the computer to check the weight of the finished (green) part and depending on the results; place the part for rework or reject the part and take the lathe out of 'continuious' or repeat operation. Now, all this I can do. The part I know little about is: should I buy a scale with a 232 port, or can I build a load center that will give me an analog output with the ability to measure 0 to 600 grams with .1g accuracy?

[Wordman]

How are you going to calibrate/zero it if you built it yourself? Are you brining this into a SCADA PC or a PLC? I don't think what you save building your own is worth it. If you dont' want to read serial, most models have analog outputs as well, standard with 12 bit resolution.

[Edward Mayer]

Follow this link, I have used these guys before and they have quite a selection of options Including communications protocols http://www.blh.com/ Ed

[Kirby K.]

Yes I believe that you can call this a SCADA system. We are running a Kurt software for statical process control. It incorperates a 24 point discreet I/O card and space for five A/D converter cards 4 input ea. Measurement is done with LVDT's presently but gives wide range of various sources with the ability to span, set gain etc. etc... The software gives the ability to 'calibrate', which would be a zero or tare function in this instance as the data collection and control is a user defined upper and lower limit. Anyway, still looking and thinking about buying a load cell (40 of them). My thinking is why pay for duplicate electronics that I allready have in the A/D converters. That is unless I have to. Still researching - need more data. thanks for the help.