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What is Lean Manufacturing?

Updated: Sep 29, 2023

The word Lean explored with the definition

What is lean?

lean is often defined as "the elimination of waste to reduce costs" and this is a fine entry level definition.

Starting a conversation on Twitter or LinkedIn about the definition of “lean” is a little like taking the top off a beehive. Many in the lean community fiercely defend entrenched positions around the differences between Lean manufacturing, Toyota Production System (TPS) and Operational Excellence (OpEx). This isn’t an article in that vein, it’s more of a personal journey of how our Co-founder - Russell's - definition of “lean manufacturing” has changed over 20 years of gemba learning.

Russell's children are 18 and 16 respectively and they used to struggle to explain to their friends what Sempai does and what lean manufacturing is. The latest offering came from the 16 year old over dinner:

“Is lean about looking at a process and working out how to make it more efficient and use materials better and make it easier for employees?”

Not bad given that he’d formed that view by osmosis. This is what got us reflecting on how Russell's personal definitions have altered over time. He's spent most of his waking life in factories since 1994 and worked for almost a decade consulting to Toyota Group and non-Toyota companies.

He's periodically reflected on his “current” definition of lean manufacturing as a kind of loose Plan, Do, Check & Act cycle (PDCA). The nine definitions below span 20 years and they’ve evolved to reflect many plateaus in understanding. Before launching into it, hat tips all round people who have influenced Sempai – Japanese Toyota trainers through the years (Muraoka-san especially), the work of Jones, Womack, Shook, Smalley and Dennis, plus others too numerous to name.

The evolution of the definition of Lean Manufacturing

It started, as it does for many, in 1998, with this:

A chart showing Toyota's approach to cost reduction

Definition 1) the elimination of waste to reduce cost…

A decent entry-level answer before a broader understanding came into view, away from purely cost and towards flow. This shows an understanding of the flow of value but in a very basic way.

Definition 2) the elimination of waste to reduce cost… and reduce lead-time

Focusing on collapsing the timeline between “paying” and being “paid” i.e success comes from whipping material rapidly through the factory so that the money sits in your bank rather than somebody else’s. Working capital improves through having less inventory on hand and dispatching rapidly to raise an invoice on your customer.

Russell got bamboozled, like everyone else, by the apparent panacea of VSM at this point and then took a diversion into VSM for non-production environments to really think about value. So, his definition morphed into something like…

Definition 3) adding more value using fewer resources

We're certain he pinched this definition from somewhere in the sphere. It ties us end-to-end from the customer (as a consumer of the product/service) all the way through the customer again (as all of us trying to conserve finite natural resources).

One drawback of 3), however, is its failure to mention “people”. Russell had been training and coaching hundreds of people in the gemba but hadn’t fully grasped “monozukuri wa hito zukuri” (make good people to make good things, broadly). Apologies but the next definition was a wordy one.

Definition 4) adding more value using fewer resources and developing the capability of people to run the right experiments in the right way, for their span of control.

There were several steps forward here as Russell started to understand PDCA deeper, rather than just parroting the words and coaching a weak version. Look anywhere in TPS and two things are required for a high level of capability:

(a) the ability to self-diagnose the gap (in your gemba and your skills);

(b) and the ability to run a decent, directionally sensible experiment to fill it.

This is why Kata is so fashionable. Put another way, (a) + (b) = self-reliance – a state of thinking-and-doing that we try to coach people towards. The beauty of “self-reliance” lies in its fractal quality for different spans of control at different levels of the business. At the top level we get to… lean as a strategy. Hat-tip again to the likes of Ballé et al for their recent work articulating this.

The next definition is when he hit peak wordiness:

Definition 5) adding more value using fewer resources by developing the capability of people to run the right experiments in the right way, for their span of control, for the benefit of the organization given current and future market conditions.

Then Russell got to thinking about Hoshin Kanri and the fact that almost everyone in a business has more work to do than time available, a basic load vs capacity issue. Of course, the load side of the equation is overstated by significant chunks of muda, muri and mura. But, for today, if you’re facing 11 hours of apparent work to do in a 9 hour day, your time to kaizen is limited.

Time has always been scarce, so any kaizen effort yields more power if it contributes, with others efforts, to a common goal. We frequently draw an alignment picture that Russell's old Manufacturing Director sketched some years ago (see below). It visualizes the power of hoshin alignment to harness many small improvements.

A picture showing Hoshin kanri with 2 different arrows

These two arrows led to another definition:

Definition 6) Alignment of effort from customer to shop floor and everyone in between.

Interestingly the definitions are coming thick and fast these days, 6) was restated to 7) below:

Definition 7) lean is about connecting your gemba to the customer in a flow of value kind of a way.

The key skill to make definition 7) a reality is “sensitivity". “Sensitivity” and “gemba sensitivity” have a very specific meaning when you spend time around strong Japanese manufacturing businesses. It’s about being attuned to your area, being present and alert, understanding the process and product to the point where you grasp deeply the SQDCP risk points and change points in whatever work you are doing.

Thus, the next stop, as a definition, was:

Definition 8) “lean is about developing sensitivity”.

Although we’re considering people now, there’s no mention of collaboration across functions. Successful lean transformation requires us to look left and right, up and down in the organization to better understand how we fit, and who we need to service better.

There's not much harm in developing the ability to recognise the challenges of your internal customers to understand their perspective; as long as it spurs action through mutually beneficial collaboration and kaizen. Which brings us to…

Definition 9) “Customer aligned gemba sensitivity and collaboration to deliver value”

Ironically, Russell's not sure he likes the way this one sounds. In trying to prune it back the fear is that it sounds like management double-speak!

In reality, we're not sure a definition matters but the act of reflecting every so often on your lean understanding is useful.

Dwight D Eisenhower once said a profound thing: “planning is useful, plans are useless”. Lean is similar: “Defining lean is useful, lean definitions are useless”.


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