I was wondering if anyone has any experience implementing SPC in a dry edible bean processing environment. I have a dry bean processing/cleaning line with a sieve mill, destoner, gravity table, polisher, color sorter, two X-ray inspections and magnets. QC samples and grades finished product hourly as well as sorts and catalogs the rejects from the X-ray inspections and color sorting. My question is can we/should we implement SPC control charts on the reject data, and if so, what type of control charts would we use? We sample rejects hourly and can both count the rejects (e.g. 10 stones, 5 dirt balls etc. etc) or we can also weigh the rejects and represent them as a w/w ratio of rejects/total product run.
My theory is if the rejects are not highly variable, then the line is stable and in control.
Any help or ideas would be appreciated. I'm not convinced this is the best way to monitor the line for control.