On behalf of Michael O'Connor, Larry Loucka, and myself, I would like to thank you for investing your valuable time this year reading our posts and sometimes sharing your thoughts. We truly appreciate your readership and we hope that we have, in some way, provided assistance in your lean journey.

In that spirit, some basic holiday lean math follows...


We are coming to the end of the year so it is a good time to reflect on where we have been and start thinking about next year. And to make the thinking definite, let’s suppose that you estimate that 85% of your customers will stick with you next year and 10% of your competitor’s customers will switch and become your customers. Is it time to open the champagne and give everyone a big holiday bonus???

And just to make the math easy, let’s just suppose that you presently have 1000 customers and your competitors have a total of 1000 customers as well. 

Heijunka, also known as level-loading, production-leveling or production-smoothing, is a foundational element of the Toyota Production System. It facilitates system stability by addressing workload unevenness (mura) through the leveling of both volume and mix over time, see Figure 1. Heijunka also serves as a pacing mechanism for operations, often reflected in the use of heijunka, leveling, or schedule boxes, which are typically designed using pitch intervals, see separate pitch post.

Accurately determining the appropriate stocking levels of perishable items is very important. Stock too few items and you will have disappointed customers. Stock too many and you’ll have unsold product - which has a high probability of turning into a loss.     

A number of industries face this dilemma each and every day.

WIP-to-SWIP Ratio

The WIP-to-SWIP ratio is a simple comparison of a process, line or cell’s actual work-in-process count versus its standard work-in-process inventory (SWIP). Among other things, a process’ target condition reflects the consistent execution of standardized work, including SWIP maintenance (which is why it should be a leader standard work audit point). No SWIP maintenance, no standardized work adherence. Accordingly, the target WIP-to-SWIP ratio is 1. 


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