Process Reliability vs Process Capability: The Differences

There is a lot of talk about process reliability and process capability in lean circles, and while many leaders believe that they have a firm grasp on both concepts, the reality tends to be a bit different in some cases. Understanding what both factors are and how they affect your work is critical if you want to make sure that the organization is evolving smoothly, and that there are always good opportunities for improvement available.

Process Reliability

Process reliability is a measure of how much the output of a process deviates from some expected values. Usually you’re aiming for high reliability, especially in situations where the quality of the output is critical for another process later on. There are various ways to improve process reliability, but it mostly comes down to tracking past performance and adjusting some variables accordingly.

It’s also important to understand that sometimes there will be an inherent low limit to process reliability and there’s nothing you can do about it. In those cases, performing well is mostly a matter of adjusting your expectations and knowing how to deal with variability as it arises, rather than trying to perfect every run.

Process Capability

On the other hand, process capability is the upper limit for how much a process can produce in a given period of time, and it’s much more flexible and open to improvements. There are various ways to improve the process capability of a system, including some relatively inexpensive ones that most companies should be able to successfully implement, and it’s important to study this aspect of your organization in order to know how to prepare it for the future.

Sometimes you don’t actually need to improve process capability to keep seeing good results from each run of a specific process though, and it’s important to learn to recognize those situations. Spending unnecessary effort on improving the capability of processes where it’s mostly irrelevant is one of the biggest sources of waste in lean organizations, and it’s a good idea to familiarize yourself with methods to deal with that. There are various statistical analysis tools that can show you exactly what’s going on behind the scenes of each process in your organization, and they can be a great way to figure out what kinds of changes you need to make in the next optimization iterations.

Aligning Both

Now that you know what both process reliability and capability are about, it’s also a good idea to understand how you can align both so that there are no conflicts between them in your organization’s processes. How you’re going to go about this depends on the specific structure of your organization itself, and in some cases you’re going to have to make some compromises. For example, you may have to sacrifice some reliability in order to improve the capability of a process, and if that improves the bottom line of the project as a whole, then it’s obviously a viable move that shouldn’t be ignored.

You’ll have to rely on statistical analysis methods quite a lot if you want to ensure that you’re moving in the right direction when trying to align these two aspects of your company. If you’re unsure about the potential impact some of your moves could have, it’s best to discuss the situation with outside experts who can shed some light on your current situation. Don’t be afraid to involve external assistance if it could potentially result in significant improvements in the company’s performance, but of course, try to solve the problem yourself first to see if there isn’t some viable solution available.