For more than 80 years, Sunnen Products manufactured bore-sizing equipment without lean principles in place. That all changed in the spring of 2006, when the St. Louis-headquartered company embarked on its journey into lean manufacturing.
Far from a machine-building giant, Sunnen is proof that lean isn’t just for billion-dollar multinational OEMs. And its effects reach far up the value stream to where the controls engineers paddle.
“They are a bit more aware of needing to find things that are readily available off the shelf in the marketplace, which allows smaller inventories and more rapid replenishment,” explains Karen Broyles, director of operations and lean leader at Sunnen. “We are looking for common components and parts that can be considered as industry standard parts. We are more aware of trying to spec parts that might have wide usage in the world, since we are not a high-volume shop.”
Sunnen’s lean approach also forces controls engineers to be more aware of the structure of the bill of materials and the effect it has on manufacturing flow. “We’ve done quite a bit of work on flattening the bill of materials, which, coupled with the standardization of design and components, allows us to have more flexibility in responding to mix changes,” says Broyles.
But that transformation didn’t happen overnight at Sunnen. Almost a year after lean initiatives were implemented, Sunnen’s first new unit reorganized around a value stream was operating in future state mode (Figure 1).
|Figure 1: Muda Free Zone
Future state maps were used to create a new machine final assembly area with significantly reduced muda.
Source: Sunnen Products.
“We previously built machines in batches of 10,” explains Broyles. “Now, we operate in one-piece flow for the machine builds. Sunnen has 13 manufacturing value streams, each with its own profit-and-loss statement. Currently, three of them have implemented the first future state map and are in continuous improvement mode. Several others are in the process of implementing the future state vision, and a few others are now in the midst of the mapping process. All value streams are scheduled to be completed by the end of 2008.”
Impressive? It is, if you understand what Broyles is talking about.
Lean manufacturing is based on the Toyota Production System, a manufacturing process developed to remove waste, focus production flow and improve customer value.
In their book, Lean Thinking, Jim Womack, founder and chairman of Lean Enterprise Institute in Cambridge, Mass., and Dan Jones, president of Lean Enterprise Academy in Ross-on-Wye, U.K., define lean organizations through five distinguishing principles—value specification, value stream identification, flow, customer pull and the pursuit of perfection.
First, companies specify value in a product that meets a customer’s needs at a specific price at a specific time. Then, the product’s value stream is identified by mapping all actions required to bring it from either concept or order-taking to delivery. Non-value steps are identified in present state maps and eliminated in future state maps. Once the value stream is mapped, parts are manufactured one at a time and flow through production based on customer orders, rather than traditional batch-and-queue assembly. Instead of scheduling based on sales forecasts, customer orders actually pull products through the process so nothing is produced upstream before a customer asks for it. Finally, the first four steps constantly are scrutinized and reevaluated as part of a continuous improvement process.
The ability to reduce batch size—critical to one-piece flow—is dependent on reducing setup times. The shorter the changeover time, the more setups can be completed.
“Lean really helped us look at product lines as a whole and work on improving the flow through the overall value stream, versus working on specific areas like setup reduction across the board,” says Broyles. “We now would find the process that would have the largest interval—the largest lot size based on setup—and improve the setup on that process.”Up the Creek
As a machine is traced upstream, it ultimately starts with the vendors’ components. And eliminating waste by reducing inventory begins before the first parts are even built. “Vendor-managed inventory has been implemented with many of our key suppliers,” explains Jeff Martin, director of operations at Washworld, builder of high-velocity vehicle wash systems in DePere, Wis. “In many cases, inventory now is delivered directly to the point of assembly. It is much more efficient, and provided a means for us to be more responsive to customer needs. We’ve been able to support and handle a significant growth in sales while at the same time increase inventory turns. Lower inventory has sped up the design process by allowing design releases to be phased into production faster.”