Flow

Making operations flow is the ultimate goal of Lean. When all the waste is reduced, every process is improved, and the excess inventory is eliminated, you are left with work that effortlessly glides through operations.

Flow is often talked about reverently. The senseis I worked with from a premiere Japanese consulting group frequently talked about flow. Next to “waste”, “flow” was one of the few words they would speak in English, to stress its importance.

Operations that flow are things of production beauty, whether in the office or in manufacturing. But flow takes a long time to fully achieve. It takes years to become a true master at making operations flow. As a result, not many companies do it well.

So, what is flow? It is the seamless linking of value-added steps in a process. Most people think they achieve flow when people and materials interact effortlessly. But there’s more.

As you peel back the layers, you start to realize how the flow of information plays its role. You see how equipment adds to flow. Even engineering plays its part in developing flow. Marketing affects flow by smoothing out the sales peaks and valleys.

Achieving flow is not limited to the shop floor.

In Lean operations, flow is often used synonymously with several other terms. Continuous flow, one-piece flow, and single piece flow all mean roughly the same thing. The more descriptive ones, though, highlight the goal of making a single part (or work unit in Lean office operations) flow through a system.

James Womack and Daniel Jones devote seventeen pages to flow in the initial discussion of the subject in Lean Thinking.

In fact, most of the principles of Lean are devoted to improving flow. Getting rid of waste makes processes flow better. Creating a U-shaped cell makes flow better. Making things visual improves flow. Reducing inventory speeds flow along.

Are you sensing a theme here? Making operations flow is important.

Unfortunately, it is hard to implement. It is surprisingly easy to recognize, though. Even a rookie at golf can identify a smooth, fluid golf swing. The same is true of Lean. If you have even a bit of production experience, you can nearly immediately tell a well-oiled, streamlined Lean organization from a traditional batch manufacturer.

As you get better and better at flow, you will even start to recognize how the movements of your hands flow during production. You will learn to place tools where you need them when you finish the previous step, instead of at a place where you have to reach for them. You will learn to orient tools for use, rather than having to shuffle them, disrupting flow.

Because process improvement is always changing operations, flow tends to get disrupted by additions of work, whether it is a new product, new machines, or an acquisition. Flexible workstations let you quickly move machines so flow can be maintained. When machines are anchored to the floor, or offices are contained in cubes, flow is harder to preserve with changes.

Spaghetti charts are great instruments for seeing how your flow really is. Track the people on your team and see how often they walk back and forth. You should strive for a single smooth line that finishes right where it started. You can even show parts flow in a different color if there is a lot of movement around a facility.

In shop floor operations, flow is easier to observe than in the office, primarily because you can see how materials move. But that doesn’t mean it can’t exist in the office. In office operations, flow is characterized by a lack of waiting for approvals or customer responses, minimal walking around the office and little or no searching for computer files. It also has few interruptions, since minor hiccups go away.

Be relentless at getting rid of anything that disrupts flow.