Category Archives: Flow

Flow Where You Can, Pull Where You Can’t

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The Shingo Model™ captures ten timeless principles that apply to all, regardless of our beliefs or level of understanding. In my experience working with companies over the past 20 years, the principle that is least practiced addresses the idea that value should be flowed and pulled. So what does it mean to flow value? Why is flow considered a principle? How does pull enter the picture and what is its relationship to flow? Finally, why is flow the least practiced of the principles?

Value for customers is maximized when it is created in response to real demand and a continuous and uninterrupted flow. Although one-piece flow is the ideal, often demand is distorted between and within organizations. Waste is anything that disrupts the continuous flow of value.

– Shingo Discover Excellence Course

It seems that since the beginning of time we’ve all learned, “Lean is about continuously developing people and improving processes to create and flow value to customers using the least possible resources required.” Value of products and services is created through a series of work processes, some which create value and some that definitely do not (think of rework, inspection, waiting and expedited shipping). One objective of operational excellence and lean is to eliminate non-value added work to improve the flow of value to our customers, the result of which is shorter delivery cycles and higher levels of quality. Some people describe this as “creating value as efficiently and effectively as possible.”

What does it means to flow value? – Flow is the relentless, steady, continuous forward progress of products, services and information to the customer. In business we create flow by removing the roadblocks that delay or prevent the continual forward motion and throughput of work. The usual suspects are the eight wastes – inventory, defects, motion, transportation, over-production, over-processing, waiting and unused employee creativity; unevenness (variation) – both in the amount of work and in the way work is performed; and overburden of people and machines with more work than can be successfully handled on a sustained basis.

The best way to describe flow is “Make One, Move One,” which is often referred to as one-piece flow, single-piece flow or continuous flow. As the names suggest, creating flow is about making and moving one item at a time (or the smallest batch size possible) through a series of uninterrupted steps, with each step in the process making exactly what is requested by the next step while never knowingly passing poor work forward.

Why is flow a principle? – If you may recall from your Shingo training, a principle is a foundational rule that has an inevitable consequence. Universal and timeless, principles apply equally to all businesses and all people. They are self-evident, meaning they seem obvious once they are identified and explained. In fact, after learning about the Shingo Guiding Principles, many people respond, “Well that’s just common sense!” Most importantly, regardless of our understanding of a principle, we are subject to its consequences.

It is important to note that Mr. Shingo did not create the Shingo Guiding Principles. Principles cannot be invented, rather they are revealed, and the core principles we cover in the four Shingo workshops come from a wide variety of people including Deming, Toyoda, Ohno, Shingo, Fukuda, Imai, Womack, Covey and many others.

Flow is a principle because it governs consequences regardless of our beliefs and understanding of flow. For example, if we don’t honor and observe the principle of flow to the extent that we stop flow in our business, what will be the inevitable consequence? Another way to ask this is, “If we stop shipping products and services our customers are willing to pay for, what will be the result?” Can you say, “We’ll be out business!”? Regardless of opinion or beliefs, this outcome would be the same for any organization: no flow = no value delivered = no sales = no cash = out of business!

What about pull? – For many years, there has been a saying in lean environments that goes like this, “Flow where you can, pull where you can’t.” Pull is a system to control production using a signal to let upstream operations know something is needed downstream. The key to a pull system is that nothing is produced or moved until an authorization signal (kanban) is received from a downstream operation. In a perfect world, we would have a seamless, uninterrupted flow of value-creating activities from order receipt, to order release, to production, to packing, to shipping, to billing, and so on and so on.

In the real world, we often encounter disconnects in the production process that force production to become decoupled. This is where flow stops and pull is introduced. For example, let’s say you run a cheese factory and production is divided into cheese making, aging, cutting, packaging, picking and shipping. In a one-piece flow environment, you would make one and then move one. With cheese, it might make more sense to produce a large batch for a number of good reasons (efficiency, quality, product consistency, etc.).

You accept this principle and know there will be negative consequences if you do not strive to create flow in your factory. You apply the principles, methods and tools of lean to remove the waste, variation and overburden from your production processes, but still do not achieve uninterrupted flow from beginning to end of the value stream. Don’t panic – this situation is encountered when production processes, machinery and physical locations create barriers to flow by decoupling the connection from one part of the value stream to the next.

This is where pull systems can be introduced to coordinate production activities between upstream (think of cheese cutting) and downstream operations (think of packaging) when their connected interdependence has been broken.

Why is flow the least practiced of the principles? – Flow is often not actively pursued because people feel it is more realistic to eliminate waste from work processes, introduce workplace organization through 5S or apply other lean tools. This is a mistake – it turns out that, when you introduce flow into any process, problems (i.e., opportunities to deliver customer value) become vividly apparent and demand immediate attention. Introducing flow can be a bit scary, but it can also sharpen your focus on improvements that will be immediately felt by your customers!