Production leveling (Heijunka) calculator
Enter each product's orders for the period and the production days: it gives you the daily quantity and a repeating cycle with the mix already interleaved.
100 per day
80 per day
20 per day
Total per day: 200 units, every day, with the same mix.
Shortest repeating cycle (10 units): 5 of A, 4 of B, 1 of C. That way the sequence can be repeated several times a day:
The preloaded values are the example from Manuel Tornell's article (University of Cádiz): monthly orders of 2000, 1600 and 400 pieces over 20 production days are made as 100, 80 and 20 per day. The order of the sequence is this site's proposal: it spreads each product as evenly as possible within the cycle.
How it works
You enter each product's orders for the period and the production days.
- Quantity per day = orders for the period ÷ production days, for each product: the same quantity and the same mix every day, as Tornell describes.
- If all those quantities are whole numbers, the shortest repeating cycle is built by dividing by the greatest common divisor. With 2,000, 1,600 and 400 pieces in 20 days you get 100, 80 and 20 per day, and a cycle of 5 of A, 4 of B and 1 of C.
- The sequence spreads the products as evenly as possible within the cycle, each time choosing the one that is furthest behind its proportion.
The order of the sequence is this site's proposal: Tornell describes the principle of leveling, not that algorithm. If the daily quantity is not a whole number, the tool does not build the cycle: adjust the days or round the orders. For leveling to work, product changeovers have to be short.
If you prefer to work in Excel, there is a leveling spreadsheet in Excel with these same calculations.
Sources
These are the ones from the article where the theory behind this tool is developed.
Why level, and what is the Heijunka box? It is in the article Heijunka: production leveling.