ONE GOOD IDEA
Categorizing another form of muda can help you eliminate it
by Jim Navetta
If you’re like me, you learned the acronym TIM WOOD to remember the seven wastes of lean, also known as muda—transportation, inventory, motion, waiting, overproduction, overprocessing and defects. Toyota also defined an eighth waste: unused employee potential.
Keeping these eight wastes in mind when creating a process flowchart is a great way to target improvement opportunities. Typically, I place an entry in red next to the particular operation and note what type of waste is in play. The idea is that the parts of the process in which we can’t find the eight wastes are probably OK, while solutions should be considered that eliminate the muda in red.
Marking on a process map is easy enough, but during the course of several projects, I’ve come across another waste that isn’t one of the traditional muda.
For example, a gas-cutting bed cuts blanks from a steel plate, leaving a skeleton behind. Obviously, this is waste of some form because you haven’t used 100% of the plate. Perhaps you’ve maximized its use, but this type of waste doesn’t fall into one of the traditional seven wastes.
In most situations, the excess material is dealt with, but not necessarily by a lean manufacturing professional. If it’s brought up by the lean expert, it’s because he or she is trying to eliminate a waste that doesn’t seem to fit in the seven categories.
Going back to the example of the gas-cutting bed, there are times when the skeleton is overused, and because of a lack of spacing between parts, thermal warping occurs, which leads to defects. It would seem the ideal scenario is one in which you max out the resource without compromising the robustness of the process.
Let’s call this waste "material underutilization." It’s important to include the word "material" so it isn’t applied to personnel—in that case, the muda is waiting, which can be addressed by line balancing.
If you’re going to address this new waste, what are the potential solutions? Start by marking a process map, or otherwise note there is a potential area for improvement. You may not have the resources to know whether there is maximum use, so identifying it is the first step.
If possible, measure defect waste separately from material waste. In a web offset printing environment, for example, roll slab waste was thrown into the same recycling bin as the defect muda that resulted from something called make-ready.
In a perfect world
Remember from single-minute exchange of die principles that you strive for the first piece of production to come out perfectly—no adjustments. Make-ready is the period from the first running piece to an acceptable product—one that has been "dialed in."
You could call the slab waste a defect depending on why the operator needs to trim the material. Some people think buying material at size is the most efficient approach. Due to variation in the supplier’s product, however, it’s common in some applications to purchase the next largest size of raw material, which is then trimmed. But the point is that completely different improvement methods are at work depending on the source of the muda.
Ensure the personnel who laid out the material use are involved in your study. If your product development engineer did the layout, were studies done on efficiency vs. defect introduction? Was a process capability study conducted on the current layout vs. other layouts?
If there is potential for improvement, perform testing and capability analyses. The lean practitioner doesn’t need to do all of this, but the leader and the team should consider the potential benefits. This testing might be handed off to another group, such as a quality or Six Sigma department, but no stone should go unturned.
Document and present your findings. There’s nothing quite like the feeling of doing a ton of analysis on a project and then neglecting to document it, especially when someone asks you about it three years later. If you’ve made an improvement, you’ll want to capture it in formal documentation for good manufacturing practices. This might include standard work.
Conversely, if you experiment and find the process is at its best, capture that finding in the event that future studies could benefit. The assumptions you based the study on today may not be valid in the future; but if they are, you want to show someone else how you approached the potential waste reduction.
Working on the ninth waste may not fit best in the realm of a traditional lean-only organization, but it doesn’t mean the lean practitioner can’t identify it. For an organization that is more disciplined—for example, one that uses lean Six Sigma—it’s a great idea.
Jim Navetta is a process improvement engineer at Reynolds Packaging Group in Louisville, KY. He earned a bachelor’s degree in mathematics from Empire State College, State University of New York. Navetta is an ASQ senior member and an ASQ-certified quality engineer and Six Sigma Black Belt. He is also a certified lean leader through the Rochester Institute of Technology’s Center for Leadership Excellence.