The traditional approach to process improvement focuses on identifying local efficiencies—“Go to the equipment, the value-added processes, and improve uptime, or make it cycle faster, or replace the person with automated equipment.” The result might be a significant percent improvement for that individual process, but have little impact on the overall value stream. This is especially true because in most processes there are relatively few value-added steps, so improving those value-added steps will not amount to much. Without lean thinking, most people can’t see the huge opportunities for reducing waste by getting rid of or shrinking non-value-added steps.
In a lean improvement initiative, most of the progress comes because a large number of non-value-added steps are squeezed out. In the process, the value-added time is also reduced. We can see this most vividly by taking a process like the nut-making example and creating a one-piece-flow cell.
In lean manufacturing, a cell consists of a close arrangement of the people, machines, or workstations in a processing sequence. You create cells to facilitate one-piece flow of a product or service, through various operations, for example, welding, assembly, packing, one unit at a time, at a rate determined by the needs of the customer and with the least amount of delay and waiting.
Take the case of the nut. If you line up the processes needed to create it in a cell and then pass the nut or very small lots of nuts from one operation to another in a one-piece flow, what once took weeks to complete can now be done in hours. And this case is not unusual. The magic of making huge gains in productivity and quality and big reductions in inventory, space, and lead time through one-piece flow has been demonstrated over and over in companies throughout the world. It always seems miraculous and the results are always the same. This is why the one-piece-flow cell is the ultimate in lean production. It has eliminated most of Toyota’s eight kinds of waste.
In fact, the ultimate goal of lean manufacturing is to apply the ideal of one-piece flow to all business operations, from product design to launch, order taking, and physical production. Anyone I know who has experienced the power of lean thinking becomes a zealot and wants to rid the world of waste, applying it to every process, from administrative to engineering. But I caution that, as with every other tool or process, the answer is not to blindly apply it by putting cells everywhere.
For example, the nut plant had created a cell for cutting and tapping. Unfortunately, they also bought very expensive and complex computerized equipment. The equipment was broken a lot of the time, creating delays. And the nuts still had to leave the cell for heat-treating—taking weeks before they came back. Inventory still piled up. The “lean cell” became a joke to the shop-floor workers who could see the waste—a serious setback to the lean improvement process.