Flow means to move steadily and continuously in a current or stream.

From a lean manufacturing standpoint, we’ve previously discussed that value is defined by the customer and the importance of mapping the entire value stream for your product or service.

Your value stream is what you’re trying to make flow.

This may seem quite apparent and like something that scarcely needs to be said. Except that most value streams don’t flow well or at all. Most products spend most of their time waiting their turn, sitting on the shelf, and being transported. All the while, they get jostled up and down and often have to sit around in their unfinished stages for months at a time. This excessive storage and processing both makes your product sad and reduces the profitability.

I find that thinking about my product as a person with thoughts, feelings, and desires helps me wrap my head around the lean production concept of flow.

I grew up on a farm, so I’m going to use natural spring water as the analogy here.

A spring comes from natural underground water sources and flows out, mostly continuously. Imagine a tiny drop of water leaves the spring. The water then trickles into a stream (or creek, in my case in Tennessee). That stream will flow into a river. The river will flow into an artificial lake created by a dam (thanks, TVA), where it will then, at some point, make its way downstream to its final destination, the ocean.

Every drop of water that leaves the spring wants more than anything to splash around in the ocean (and who can blame it?). So, our water doesn’t like waiting, loitering, or queuing. The biggest queue of them all is the man-made lake.

If you think about just how long any droplet of water, having made its way into the lake takes to then leave the lake on the other side, it’s easy to say that it’s a hell of a long time (for most decent-sized lakes).

So, what is our tiny little drop of water doing in the lake? Well, it’s probably floating around, observing various fish and marine wildlife that inhabit such lakes. It may get splashed around by a boat before dropping back below the dark surface. It may make a few friends with some marine algae. But mostly it’s just waiting. It wants to get to the ocean, but it can’t. It’s bottlenecked by a dam. In short: Our drop of water is lonely, bored, and not moving forward.

Why take the time to discuss a single drop of water?

A single drop of water in a stream is like your products going through their value stream. Each one desperately wants to get in the hands of the customer. Your products don’t like waiting on shelves or being picked up or put down continuously (over processing). They don’t like sitting in their incomplete and unfinished state (certainly feeling vulnerable as such). They want to be as valuable as possible as soon as possible and in the hands of your customer.

But what most often happens is that your product spends greater than 90 percent of its production life waiting, often on a shelf or in a computer folder somewhere. Your product often remains in its ugly, unfinished state for months, when the entire value stream is considered.

And what kind of boring life is that?

The goal of flow from a lean enterprise standpoint is to reduce all eddies, lakes, and pools where your product collects (we typically call these “storage” or “warehouses” or “inboxes”). It’s about optimizing the value stream to where the handoffs from one person to another are smooth and the product flows continuously to meet the demand of your customer.

And, just like how the customer defines demand, so the customer also defines the rate of flow through the organization.

Understanding flow is best done by pretending your product or service has feelings and remembering that it desperately wants to be with your customer. If you put yourself in the shoes of your product and walk its path backwards, from finished good to its raw materials (and even the sourcing of those raw materials), you’ll find your products are sad much of the time, as they’re unfinished, sitting on a cold shelf, and not fulfilling their potential.

In future posts, we’ll discuss specific ways to achieve flow.