In developing a Lean operation we seek amongst many things to stabilise what is otherwise often an unstable manufacturing environment. Some authors have likened the manufacturing environment to the 2nd law of thermodynamics in that left by itself the system will gain entropy – in this case order will over time become disorder.
If you like you can consider that plans are like the structuring of ice when water freezes: left by itself the ice melts and the structure is lost. Management is like the constant energy that must be applied to cool the ice.
(remember the old chestnut: There is an open fridge in an empty room, what happens to the temperature of the room?)
To put it another way, it is like Murphy’s Law:
If anything can go wrong then it will.
Lean system theory places significant emphasis on managing stability. It argues against over-reliance on conventional top-down management which is often seen as bureaucratic, unwieldy and slow to react, replacing it instead with bottom-up techniques that focus on shop-floor activities and teamwork. These are centred around the concept of Visual Management rather than IT-centric solutions.
In doing this, Lean is seeking to empower the shop-floor workers and supervisors/team leaders to respond to any sign that the desired system state (like the ice above) is degrading by taking immediate corrective action. In this way the stability of the system is maintained.
Note: Top-down planning is required in Lean and is addressed by Hoshin Planning.
Why is stability important?
It is easier to maintain and then improve methods if the nature of the work is in some way regular, standard or even. In this kind of environment abnormal situations stand-out like a sore thumb; recognising that a problem exists is the first step in dealing with it. In a stable environment the inputs and outputs are more repeatable and as result we are likely to observe better quality levels, less waste and higher efficiency.
These benefits are not limited to individual work-centres or factories but also extend into much greater systematic benefits across the value-stream and across the supply chain. Recall that the Forrester Effect is caused in part by the amplification of errors from one level to the next. Instabilities are direct causes of errors and are also the reasons why planners amplify the signals: they do this to ‘protect’ themselves from uncertainty – both in their own company’s system but also in those of their suppliers and also their customers.
Denis identifies 5S and TPM as pre-requisites for Lean. Although there are many other necessary activities that will improve the environment for Lean these are as a good a starting point as any.
So whats this 5S thing then?
5S is a useful starting point before starting to implement lean, it helps establish a more controlled environment in which stable operation is easier to achieve. It is not limited to lean but can be usefully employed at the start of any major improvement activity.
Why ‘Engineering Stability’?
As engineers we are charged with finding ingenious ways to solve problems. Stability is rarely the natural case, customers’ needs are constantly changing and most companies are having to serve increasingly fragmented markets. So we have to find ways to manipulate the environment in some way to achieve an operational stability i.e. we need to engineer a solution.