This image, used as a depiction of a process with minimal waste, was first examined last week with regard to defining what lean is. This timeline shows an ideal state for any process, where there is zero time for the product/service/work-in-process (WIP) to be spent between steps of a process – this means there is zero waiting between steps, and as one step is completed it immediately flows into the next step with no stopping.
This is a very simplified example of continuous flow – one of the lean tools (that will be examined later).
The beauty of continuous flow is that it features stability, continuity, balance, and doesn’t waste time (the non-renewable resource). No time wasted on waiting between steps means time is being maximized for its capabilities. You can’t have a waste-less process without continuous flow, as it is the truly ideal process state.
However, the troubles with continuous flow are that it’s very hard to achieve, process steps aren’t generally balanced, and all process contain inherent waste activities. When one starts out to achieve continuous flow, many process problems will appear and come to the surface. Most individuals think this is bad – it’s actually a good thing. The optimal process features continuous flow, and any problems that stand in your way from achieving continuous flow are problems that are now visible and can be rectified.
And this is Toyota Way Principle #2.
“Create a continuous process flow to bring problems to the surface.”
Waste activities do a few bad things. First, you’re wasting time and money on their existence since they delay the time it takes for you to get paid. Next, they mask big problems within the process that could be fixed if they were more visible. They also provide a degree of insulation from stockouts.
By trying to force continuous flow on a process, the insulation goes away and the problems come to the surface – this means you have to attack those problems instead of ignoring them.
All lean activities should be organized with the intent of generating continuous flow – identifying problems and solving them, balancing the load and the lines, reducing wasteful activities during and between process steps.
We’ll cover continuous flow later on – more details about what it is and how to implement it – but suffice to say that by reducing wasteful activities in a process and optimizing steps within a process so that the load is balanced between operators and little time is wasted on products/services/steps waiting, you will get closer to creating continuous flow.