Single Piece Flow

Single Piece Flow is something I wish someone would have told me about when I first started scrum. For me, this is at the heart of the agile mentality. When I first learned it, it kept me up all night thinking about it.

Single Piece Flow is part of the Toyota Production System (TPS), which is where we get Lean. And Lean is Agile’s daddy. Best to know your roots!.

Single Piece Flow is a manufacturing concept. Traditionally, in manufacturing, companies produce items in what’s called a batch-queue. In the example below, we have a monitor producing company. First, the upper part of the monitor is created. In this example, they produce 10 in a batch. When the upper part sections are completed, the batch goes to the next department and the base of the monitor is added. When the bases are completed in that batch, the now assembled monitors go to QA and are tested in another batch.

Single Piece Flow2

Lets pretend that it takes each department 1 hour to finish each batch. So, for the first department, it will take 10 hours to complete all 10 monitors. The second department will take another 10. QA will take another 10. So, to complete all monitors from assembly to QA, it will take 30 hours to complete. The easiest way to do this is just count each monitor or QA going left to right in each row.

Follow me so far?

So, lets ask ourselves a few questions (just count left to right on each row to get the answer).

Questions 1

Lets throw in a hypothetical. Let’s say the first department created a defect in one of the monitors (indicated with the X through the screen).

Single Piece Flow defect

Now lets ask a couple of more questions.

Questions 2

That’s the traditional batch-queue mentality. Now, lets look at Single Piece Flow. Single Piece Flow approaches completing one item at a time. In other words, the first department makes one top portion of the monitor, the second makes the bottom, then QA tests it. Boom. One monitor done. Lets now ask ourselves the same questions again. NOTE: in Single Piece Flow, once a department finishes its portion of the monitor, it goes right to the next monitor. So, when the second department is attaching the base of the first monitor, the first department is already working on the next monitor. Kapish?

Here’s the chart again to help you out. (hint, count by columns instead of by rows).

Single Piece Flow defect

Questions 3

Pretty incredible isn’t it?

For me, single-piece flow demonstrates the power of agile. Its focused, its flexible, its faster, and it decreases waste.

Now imagine if instead of hours we were using days? Weeks? And all that time equates into dollars. Amazing. Be sure to pass this around. It could rock some exec’s world.



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