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How to find Abnormalities and not Problems in a lean factory

Updated: Sep 13, 2023

A car parked by traffic lights on a hill

Real life examples of lean thinking

The picture at head this blog is a great way to explain Change Points (Henkaten) - an important lean principle - through real life. People serious about understanding lean and kaizen tend to embrace the world around them, by mining for examples. We've put out blogs ourselves about discovering kaizen examples in elite pro sports and improving flow, by reducing delays, in a department store cafe.

Change Points (Henkaten) and traffic lights

The picture shows the traffic lights at the bottom of the long raking downhill drive into the market town of Ashbourne in Derbyshire (where I currently live). On this day, I was walking back up the hill and noted something of interest. If you look closely at the middle left of the picture, a car is parked up on the kerb. Squint a little harder and you'll note that the sign on the back of the car says "Traffic Signal Maintenance".

This I noted because it represents a potential change point and those who run strong lean businesses love Change Point Management (even though they may not use that exact terminology). In tandem, they embrace the time-travelling benefits of the mantra "find abnormalities NOT problems"

What are Change Points in manufacturing?

Change points were a Eureka moment for us at Sempai. Think about this statement:

Most defects and accidents happen after something has changed

If you had the same...

  • trained people (Man/Woman) turning up every day

  • with good quality parts (Material) that arrived on time

  • manufacturing with the right machines/tools that didn't break (Machine)

  • following strong Standardised Work (Method)

  • with the right lighting and temperature (Environment)'d have less problems that you do currently, right?

Example Change Points (5M1E) with examples

Man/Woman (People)

changes to people working in the area that might affect how well things run

e.g absenteeism or holiday


changes to machines, jigs and fixtures that might affect how well things run

e.g a change to settings of a machine tool


changes to the way the machine operates or the Standardised Work of the operator

e.g process conditions altered during the outgoing shift


changes to the parts or components (materials) used to make the products you sell

e.g trialling new material with a current supplier

Measuring Equipment

changes to the gauges used for quality assuring the products you sell

e.g torque wrenches going to, or returning from calibration


changes to the conditions you make your products in

e.g it's a hot or cold day – known variability caused by temperature changes

Find Abnormalities NOT Problems!

The key lies in recognising that many defects and accidents happen after something changes. As I knew I would be driving down the hill later, several thoughts occurred to me;

1) This is a potential abnormality as there's no guarantee that the lights will behave exactly as before

2) Is it routine maintenance OR a change to the sequence OR a change to the timing?

3) Either way, the lights might operate differently OR the confirmation that they work as intended after the maintenance may be flawed.

When I approached the lights later that day it was with a heightened sense of awareness for my own driving with an eye on the potential confusion of others. This is the strong operational practice of spotting & reacting to abnormalities (traffic signal car parked) rather than sorting the subsequent problem (accident).

We summarise this approach in our award winning digital lean toolkit SempaiGuide with an example from a pub/bar:

a screen shot from SempaiGuide

another screen shot from SempaiGuide

Spotting the bottle leaning against the glass, and standing it back up, is a lot easier than clearing up smashed glass and sticky sugary mixer.

Lean Manufacturing Examples

Factory examples? take your pick... new operator on line, new supplier for an existing part, change to the way a machine operates, kaizen changing the work sequence on an upstream process etc. If we brief these out to our people on the shop floor in advance, they are forewarned and we can manage around the Change Point.

The great thing about living the 'Change Point' life is that it holds your feet to the fire to define normal (Standardisation) so that abnormal becomes very obvious. It also draws supporting functions like engineering and materials into closer communication with Team Leaders on the gemba. What's not to like about that?

If you'd like to know more about training your Shopfloor Leaders to see problems before they occur, take a look at our courses and coaching.


48 views2 comments


Hey Russell, great post. We have recently been adding to our lean language dictionary. Your explanation of how henkaten is different from gemba or value (change in the product that the customer will pay for) is exciting and very helpful. I also appreciate that you tie in the fact that people are part of the process in a way that isn't derogatory or belittling. One thing this bit made me think about was how people naturally aren't the same day to day: maybe we had a row with our spouse, perhaps there is political tension within a workforce, or even an accident the previous day that changes the outlook that individuals have about the work or themselves. Of particular note…

Replying to

Hi Andrew, thanks very much for your kind comments and your interesting point about people changing day to day. It ties in well to one of the other skills of a Team Leader & Supervisor I think - The Daily Huddle / Start of Shift Brief. One of the first things a strong TL does is take a look at their gathered team and think "does anyone look different?" - people who are normally up might be subdued, someone mifght look a bit stiff or preoccupied or have dilated piupils even. A good calibration to know who they ned to check in with quickly after the 5 min Team Brief / Huddle ends. It's a part of this blog


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