As quality professionals, we are often asked to fix parts or processes that are not functioning as intended. In most of these cases, only a small percentage of parts or process occurrences are non-conforming. There are two choices we face when deciding how to address the issue—change the design, or reduce the variation. Changing the design is the lazy choice. Why? Because it’s easy. Something is broken, make it thicker! A process takes too long, add extra manpower! There are a lot of consequences associated with the lazy choice—long lead times, added part cost, tooling costs, manpower costs, unintended failure modes—all costing your company money and time that don’t need to be spent. However, the biggest transgression with the lazy choice is that you never truly understand root cause. Therefore, the failure mode can return again in the future—perhaps on a similar part or process—and you’ll be right back in the same boat again. My challenge to you is to make the hard choice. Practice DMAIC and reduce the variation! Choosing to reduce the variation is the difficult choice because it forces you to understand how the part or process is supposed to work, through engineering, physics, or logical thinking. This understanding will likely lead you to a meaningful hypothesis test, designed experiment, or multiple regression, which will guide you to the root cause of the variation. Reducing the variation can be as easy as changing a process parameter, altering a preventative maintenance schedule, or replicating best practices. Not only are these changes generally free, they are also fast to implement—saving your company precious time and money. The best part of making the hard choice is the learning. You will be able to protect new designs and processes from this failure mode because you will have complete understanding of how the part or process is supposed to work. My question to you—what choice will you make?
Scott C. Sterbenz, P.E.
ASQ Six Sigma Forum