PlantmarginCost per unit by production lot: let the best shift set the standard
Most plants know their monthly cost per unit. Few know that the best shift last week made product 15–25% cheaper than the worst, on the same machines and the same raw material.
Why the spread matters
The spread between the best and worst lots is a saving the plant has already proven it can achieve. It needs no new equipment, only repeating the conditions of the best lot:
- the order of starting machines;
- dryer temperatures;
- loading, and idle running at shift change.
How lot costing works
A lot (a batch, shift run or order) has a start and an end. Over exactly that period, sum:
- the electricity of every section;
- the fuel;
- the output.
Then:
cost per unit = (kWh × all-in rate + kg fuel × fuel price) / units produced
Compare each lot with the recent average and with the best lot.
Making it stick
- Show the current lot's cost per unit live in the control room, against the recent average.
- Review the best and worst lot of the week at the production meeting, and agree what was different.
- Turn the answer into a standard operating procedure, and check that the next week's spread narrows.
Plantmargin creates lots automatically per shift, or from your batch records. It works out each lot's energy, fuel, cost, quality and yield from the meters, so the conversation starts from facts.