Friday, October 28, 2011

Example of Production Culture KPI: Volumetric Productivity

Say you are running a 2g/L product from a ten-day process at your 1 x 6000L plant, with strict orders from management to minimize downtime. This product is selling like gangbusters, which means every gram you make gets sold, which means you've got to make the most of the 80-day campaign allotted for this product.

The volumetric productivity for the process is 2g/L/10days = 0.2 g/L/day.Running a 6000L capacity plant gives you
  • 12 kilos every 10 days.
  • 8 run slots given the 80-day campaign
  • Maximum product is going to be: 96 kg for the campaign.

But suppose your Manufacturing Sciences team ordered in-process titer measurements and found that Day 8 titers were 1.8 grams per liter. in process titersHarvesting at day 8 means:
  • 10.8 kilos every eight days.
  • 10 run slots given the 80-day campaign
  • Maximum product is going to be 108 kg.
By harvesting earlier, you gain two additional run slots... during which time you can make 21.6 kg; but since you lost 1.2 kg/run for 8 runs totalling 9.6 kg, the net gain is 12 kgs.

There are a lot of assumptions here:
  • Your raw material costs are low relative to the price at which you can sell your product
  • Your organization is agnostic to doing more work (ten runs instead of eight).
It is difficult for plant managers to end a culture early to get 10.8 kgs when simply waiting two more days will get you 12 kgs. It quickly becomes easy when you see how two-run slots open up and you have the opportunity to make 21.6 kgs to make up for the lost product from ending the fermentation early, or rather, the point of maximum volumetric productivity.

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