Stability

The term stability is the tendency of something to keep its current state. The opposite of stability is Lean operations is variation, or the state of things fluctuating wildly, or drifting away from normal.

Stable processes tend to not only produce high quality outputs, but also do it in a predictable time with a minimal amount of waste.

In continuous improvement, stability is most often used to describe a process. If a process is stable, there is little fluctuation in the output. This is sometimes referred to as being “in control”. Out of control processes exhibit a trend, or significant fluctuation.

Continuous improvement generally strives for a reduction in variation, and that occurs by stabilizing processes. Stability means predictability. Predictability means planning gets easier.

Ways to Increase Process Stability

1. Implementing Standard Work. The more consistent the process, the more consistent the results.
2. Ensure teams are properly trained. Take as much human error as possible out of the system.
3. Use good components. If parts are inconsistent, they disrupt the flow of a process.
4. Maintain your machines. Keep your machines from making your processes fail.
5. Use high quality tools and machines. Poor tools are hard to use consistently.
6. Use daily management. It is hard to stabilize a process that is not measured.
7. Implement countermeasures. Systematically eliminate the little things that disrupt processes.

Stability also is used to describe other things, such as a computer system that doesn’t crash or change, or a functional system, like a materials system. If a system is stable, it will provide consistent results.

You may also hear about stability when talking about demand. Employees like stable demand, as it is comfortable, and easy. Companies, however, want a smooth increase in demand. They have to be careful, though. If the increase is too fast, problems develop, and the trendline gets jittery. If the increase is too slow, though, shareholders complain, and financing becomes more challenging.