Extra Point

October 2006

by Jack Tenney, Publisher

Run-Change-Down Times

You are no doubt familiar with some version of what custom manufacturers use to schedule orders — it’s called R-C-D, which stands for Run-Change-Down-times.

Like you’re making wallpaper, let’s say. It takes you an hour to set up the machine to run the polka dot 44723, which can be output at 30 rolls per hour, and history tells you to schedule the machine as if it were a psychiatrist and only worked 50 minutes an hour. Therefore, if you had a factory order for 90 rolls of that ever-popular 44723 polka dot paper, you’d need to schedule the machine and crews for four hours and 40 minutes (three hours for run time plus one hour for change time and 10 minutes of down time per hour). You get the picture: Longer runs are more efficient, as in you can produce more finished product per hour the more units you produce at a time.  If you ever set up to run just one roll, you’re looking at two hours 10 minutes!

It’s not unlike driving to Boston. It’s 210 miles to your friend Louis’ house, and the speed limits are such that you can expect to average the old mile-a-minute. It will take you about a half hour to pack the car and fill up with gas. You should figure up to a half hour for pit stops and traffic jams on average, like over 10 trips. If you were thinking of going 15 miles farther to Logan, figure more like an hour on top of that.

If it’s 8 a.m. and Louis has tickets for the BC game with a noon kickoff, how do you make it? The mileage takes three and a half hours. Then there’s the gas run you should have made  last night and you pray there won’t be any delays or pit stops. Right? But you always make it in three and half hours, even with gas, McDonalds’ breakfast in Randolph and  a little traffic snarl in Brighton.

How?

I get it. The messing around still takes a half hour, but you drive at 70 instead of 60. 

That’s how it works running a factory, too. Not much you can do about C and D, you make it up in R, which, like speed limits, is based on less than maximum mechanical limits. And no factory crew ever was issued a ticket for going too fast.