Lean Manufacturing For The Job Shop

Lean practices are not just for predictable production. Here are the common-sense ways this low-volume job shop has implemented a leaner process.

Article From: 11/16/2007 Modern Machine Shop, ,

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For the few jobs the shop runs on a kanban basis, tools are kitted and stored in a single location. Recognizing the value of having this tooling all together and ready to go, shop personnel now consider it practically taboo to dip into one of these kits for the sake of using a tool for a different job.

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The shop specializes in complex work in challenging materials, much of it for military applications. The cylindrical part in the top photo, for example, is a housing for an airborne laser system that was machined from age-hardened titanium.

multitasking turn-mill machines

As an alternative to separate setups on milling and turning machines, the shop is moving toward more use of multitasking turn-mill machines for efficient processing of low-volume parts. Operator Gary Barnes can be seen here at one of the shop’s Mazak Integrex machines.

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Instead of sitting idle while operators search for tooling, machines now produce while operators stage the next jobs. A step as simple as buying more straps made it easier to prepare workpieces to be quickly loaded as needed.

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Tricia Gerak is CEO of the business. Anthony Gerak is president. The machine behind them is their newest purchase, an Integrex able to accommodate 30 inches of swing and 100 inches of length.

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Another lean manufacturing discipline is cellular manufacturing. The shop applies this practice in just one case. A regular customer has the shop machine hubs for tire testing machines. The hubs come in various sizes, but there is enough family consistency from hub to hub for the manufacturing process to be standardized. A milling machine, a CNC turning machine and dedicated gaging are grouped into a tight cell so that one operator can easily produce these parts as needed. Here Mr. Gerak speaks with that operator, Dave Brozovic.

“Ninety percent of ‘lean’ is useless to us,” says Tricia Gerak, CEO of Canton, Ohio-based Precision Component Industries.

Precision Component is a job shop specializing in high-end, low-volume, complex parts made from hard-to-machine materials. Much of the shop’s work, for example, relates to hardware for precision military systems. Lean machining tends to accept cycle time as a given, optimizing the surrounding process to minimize inventory and waste. Setup time reduction is an important component of this. However, for Precision Component, setup time is a given as well. Many of the shop’s jobs are short-run parts for which the setup has to be invented on the fly. For this reason and others, Ms. Gerak assumed that the disciplines of lean manufacturing had nothing to offer her shop.

Then she attended a session on lean as part of a supplier seminar held by a major defense contractor. She posed questions to this session’s presenter. He was astute enough to perceive how her shop’s situation was different, and he interpreted lean principles for her in light of how a low-volume job shop might apply them. That conversation changed her thinking.

“I realized I had to let go of my paradigm that lean didn’t make sense for the job shop,” she said.

In fact, there was a part of lean that did make sense. Specifically, there was the other ten percent.

Clearing The Aisles

Anthony Gerak is president of Precision Component. He and Ms. Gerak committed to streamlining both the business and the shop floor in light of their new understanding of lean, and they explained these changes to the company’s staff. To begin, they cited the many well-known aspects of lean that they would not be implementing. There would also be no kaizen events, they said. There would be no 5S, and the shop would not even install peg boards. That’s because the range of potential jobs is so vast that the range of tools needed is unpredictable.

However, there would still be fundamental change. One of the most striking examples is a move to a more lean approach to ordering raw material. The purchasing manager used to order stock as soon as the production order was received from the customer. The perceived advantage was that the shop would have the stock on hand “just in case” it had a chance to run this job. Pallets of raw stock crowded the aisles of the shop floor.

Today, the aisles are clear—but that means they are also clear of this reassuring visual evidence of the shop’s backlog. Employees wondered: Does the shop still have plenty of work?

Absolutely yes, the Geraks explained. They went on to explain the reason for the change—a reason they now see as common sense. In the past, the shop had not stopped to consider just how much money it was spending to own and store that material. Today, the plant manager and the purchasing manager coordinate their actions. Material is ordered no earlier than two days before it is needed. As a result, all of that capital that used to be tied up in raw material is set free for a more productive use, such as investing in additional tooling and equipment.

“I Had To Go Find X”

Streamlining processes on the shop floor came next. To do this, the shop simply looked at one recurring job that had a variable processing time to discover where the variability was coming from. From this, the shop learned a great deal about where time was being lost on all of its jobs.

In analyzing how shopfloor personnel spent their time, a common theme emerged. To account for one instance of a job running long, the operator said, “I had to go find the right gage.” In another case: “I had to go find a toolholder.” Operators were walking the shop floor in search of the tools, hardware and accessories they needed. The solution to this problem was to purchase more of all of these items so that whatever operators needed could always be close at hand.

The Geraks now stress this important point to employees: Whatever you are looking for is not as valuable as the time you spend looking for it.

The appearance of frugality can be deceptive, they say. When the shop acquired its most recent machine, a used Mazak Integrex 50 multitasking machine able to run workpieces as long as 100 inches, the management decided to buy new toolholders that would be dedicated to it. Employees questioned the need because there seemed to be enough toolholders in the shop. However, it would be far less expensive in the long run simply to have plenty of toolholders, Ms. Gerak says. She adds, “If I can spend $1,000 on tooling to save 30 minutes per day of walking around, then that is easily worth the expense.”

In fact, because they are not searching, employees now have time they didn’t have before. While the machines are running, they can now stage the next job and the job after that. Staging jobs in this way ultimately revealed another shortage that was leading to waste. Operators were walking the floor searching for the belted straps that wind around large workpieces so the crane can lift them. The shop was short on straps—a simple, low-cost item. Employees spent labor cost on looking for straps because looking around was such a common part of the shop’s practice. Now, the shop has decisively remedied this problem simply by purchasing many more straps for the shop floor.

Move To Multitasking

The move to multitasking machines such as the latest Integrex began when the shop purchased a smaller Integrex machine in 2004. In addition to realizing it could benefit from multitasking, the shop discovered that its CAM system, GibbsCAM, makes it relatively easy to program even this more complex type of machine.

Many production facilities would not see a multitasking machine such as this as being consistent with their application of lean manufacturing. One station where a lot of machining is performed could be seen as a “monument”— a place where parts queue because batching is necessary to hold down the unit cost of this work. For established parts in predictable production, a series of simple stations can often avoid this work-in-process inventory.

However, that doesn’t describe Precision Component. Many of this shop’s jobs involve short runs of complex parts that were unknown to the shop just days prior. Batching these jobs isn’t a danger—the quantities are too low. Running jobs such as these in one setup on a multitasking machine has proven to be much more efficient than setting up the part first on a lathe, then on a machining center. Thanks to the shop’s growing reliance on multitasking, machining centers now run just one shift instead of three.

More Multitasking

In fact, multitasking of a higher order represents the direction in which the shop now finds itself headed. Instead of stopping at just machining the components, one major customer has asked the shop to also assemble the finished product. That product (a specialized machine—the shop asked to keep its nature confidential) is now built on the shop floor to the customer’s specification, then sent to the customer complete.

The result could be thought of as lean manufacturing from the customer’s perspective, because the customer’s ordering process has become much more streamlined. Instead of making separate expenditures for separate manufacturing steps, Mr. Gerak says this customer can now obtain the fully manufactured product for just one line item on a purchase order.

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