Kaizen Song: (SWIP Can’t Be) Zero

Tony asked in a comment to an article about how to calculate standard work in process (standard WIP):

Can I ask you a question: Standard WIP = One piece flow?

No Tony, the two are not the same. The minimum necessary amount of stock to keep flowing one piece at a time is known as SWIP. The key point to remember is that one piece flow does not mean zero work in process. The work in process (WIP) levels will drop drastically when compared to traditional batch and queue process design, but the pace of customer demand (takt time) and the process cycle times will require that the standard work in process (SWIP) quantity is calculated and maintained in order to keep the process flowing.

If one piece flow is a river flowing to the ocean then SWIP (also called standard in-process stock) is like a series of locks that let the water collect to a certain level before continuing to flow through obstacles. As the article above explains, processes with cycles times longer than takt time require one or more pieces of SWIP in order to maintain flow. These include batch processes, outside processing, drying or curing time and several other specific conditions explained in the article.

Most people are not aware that David Bowie was answering this same question in one of his hit songs, although for some reason the record company decided to change the words when the record was released. Here from our kaizen songs archives is…

(SWIP Can’t Be) Zero (from Heroes by David Bowie)

Why, why do we think
“Oh when, will we become lean?”
Though kaizen will drive waste away
We’ll always see waste, just flow one piece
SWIP can’t be zero, when we flow one piece
And you, you can go see
And I, I’ll check all the cards
Because we’re leaders, we manage by fact
Yes we’re leaders, we have our own takt
Though on-time, and stock turns keep getting better
To shorten lead times, just flow one piece
SWIP can’t be zero, when we flow one piece
P-D-C-A
By counting our SWIP
From the dock lanes, the dock lanes to ship
Though on-time, and stock turns keep getting better
We can see waste, for ever and ever
Oh SWIP can’t be zero, when we flow one piece
Why, why do we think
“Oh when, will we become lean?”
Though kaizen will drive waste away
SWIP can’t be zero, when we flow one piece
We can see waste, just flow one piece
I, I can remember (I remember)
Standing, in the circle (in the circle)
Andon lamps, flashed red over our heads (over our heads)
Targets missed, workers stopping to call (stopping to call)
And the blame, was always assigned
Problems were hidden, hid by high stock levels
SWIP can’t be zero, when we flow one piece
SWIP can’t be zero
SWIP can’t be zero
SWIP can’t be zero
Just flow one piece
SWIP can’t be zero
“We’re batching, and batching protects us”
Like we were blind, when we covered mistakes
But stock could be lower, just flow one piece
Oh-oh-oh-oh, oh-oh-oh-oh, just flow one piece