Re: Overall equipment effectiveness - Computing OEE taking all machines taken togethe
At a macro level, measure OEE like you would any other machine or part. You are just likely to have more set-up time that needs to be accounted for, and the consideration of different cycle times for different parts. Make sure you break it down into one shift increments for data collection and analysis. Trying to record an entire day if running three shifts and your likely to run into complications from lost information/data, changes in parts requirements or other variables throughout the day that makes it more difficult to track.
Something to heavily consider though, is that OEE isn't a one size fits all application, it is really meant to be used in conjunction with a larger system to identify and then address waste (machine downtime, poor cycle times, long set-ups, quality, etc.) present in the system. I wouldn't try to apply OEE to every piece of equipment, there really isn't any need, but instead use it as part of the larger strategy to identify root causes.
If you have more questions about a specific machine, it may help to download one of the
OEE spreadsheets available here and populate some of the basic information (shift length, breaks, etc). Create another worksheet inside the file and populate it with some of the information you have available by part number (keep the part number generic: A, B, C, etc.) so there is no issue of non-disclosures not being signed. Information that will be needed is set-up time, cycle time (from the start of one piece to the start of the next piece on the machine), first-pass yield, scheduled maintenance, and typical lot sizes (just make an educated guess for this exercise).
Do that and shoot me an e-mail with the information. I'll then re-post the spreadsheet with my comments.
Wayne
