Building Better Powertrains Through Lean Approaches at Toyota

Toyota Motor Manufacturing West Virginia (TMMWV) makes some of the most efficient and reliable four- and six-cylinder powerplants in the world. This month, the facility will become the first outside of Japan to be entrusted with making automatic transmissions, and in 2003 it will begin making powertrains for Toyota's crème de lá crème Lexus channel. You might think advanced process technology is the secret to their success. The truth is that while the people at TMMWV are not exactly Luddites, the dogged pursuit of the Toyota Production System—through simple visual management techniques and standardization, standardization, standardization—helps set them apart.

The first thought that enters your mind when you step through the doors that open onto the plant floor at TMMWV is, "Where is everybody?" For a facility that is cranking out 800 four-cylinder engines and 600 six-cylinder engines every day, and machining an additional 400 engine kits, there is a definite dearth of human activity. Tow motors pulling carts laden with parts are not whizzing by.Clipboard-toting managers don't brush past on their way to monitor some new production problem. All is quiet except for the gentle hum of the long line of machining centers making parts with an exactitude measured in microns. As it turns out, this first impression is pretty accurate. There are only seven maintenance team members ("team member" is Toyotaspeak for everyone from the president to the janitor) assigned to the four-cylinder machining areas and seven more for the six-cylinder areas. The addition of three machinists known as the "kaizen team" swells the ranks to a grand total of 17. And this kind of lean staffing exists throughout TMMWV. Toyota can operate in this mode because of a single-minded pursuit of the lean practices of the Toyota Production System (TPS). Oh yeah—and some merchandise from the local Wal-Mart.

Traffic Cones and Bicycle Flags
Phil Duncan, assistant general manager of Manufacturing, points out the multitude of little things that add up to lean production at TMMWV. Passing by one of the many machining centers, Duncan indicates a bar of purple color painted along the top edge of a machine and corresponding bar on the controller for the machine. With so many nearly identical machining centers, finding the right controller in an emergency could take some time. With this simple color coding system identification is immediate, which saves precious seconds in a down time situation. Similarly, of the four bolts that secure the steel mesh guarding on each machine, only one is torqued down; it's painted red. The other three are slotted. When a repair is necessary only one bolt need be removed, reducing the time needed to access the problem by 75%.

TMMWV on JIT
"I've seen many, many industries try to go in and have just-in-time inventory, the first thing they do is drop their inventory and they crash and burn, they can't make production and they're running out of parts and lines are shutting down and they think, this stuff doesn't work. Well, just-in-time is a result of doing all other things well–preventive maintenance, logistics, quality approach, safety–all those things done well end up allowing you to run with low inventory." – Phil Duncan, Assistant General Manager of Manufacturing, TMMWV

The sum of small measures like these allow Toyota to staff leanly and get the most out of every team member. The kaizen team of three machinists bears that name largely because they spend most of their time fabricating parts based on someone's kaizen idea, not making repair parts. Duncan estimates the percentage of their time spent on planned maintenance versus unplanned repairs at "Way over 50%." (He says this in a way that makes the listener think 80%, not 57%, but Duncan refuses to jinx his team by giving a more exact number.) Based on his many years of experience at both General Motors and TRW, Duncan calls this salutary ratio "extremely unusual."

Moving on toward the production control area, Duncan stops to indicate a red traffic cone sitting inside a square taped on the floor. Beside the cone there is an identical taped square. Duncan moves the cone from one square to the other. "This means we don't need material at this operation," he says. He moves the cone back to its original resting place. "This means we do." Duncan almost looks a little embarrassed by the stone knife level of technology, but it works. That's what matters. In the same exceedingly simple-but-effective vein, each parts rack in production control is topped by an orange bicycle flag. When the flag is up it means that a minimum inventory standard has been violated and more parts are needed. This "high-tech visual control," as Duncan jokingly refers to it, allows any production control manager to immediately assess his parts situation without reference to a clipboard or a computer screen.

Piling On
Stationed beside the final assembly line is another key to Toyota's low tech visual management–the yamazumi board. Yamazumi translates as "to pile in heaps," and that is a fair description of what one sees on the board. Magnetic strips of varying width are stacked one on top of the other forming several columns across the board. A scale of seconds is marked off beside the columns, and a pink thread is pulled taunt across the board at the 65 second level. Each strip represents the time it takes for an assembly team member to complete a task; each column represents total takt time. Whenever process rebalancing needs to be done because of increased production or a new product introduction, tasks can be quickly rearranged. Also, any underutilization of a team member's time can be recognized immediately by seeing a column that does not make it up to the pink thread.

While standardization of process times for assembly is familiar territory to the automotive industry, Toyota is seeking ever greater efficiencies by expanding the use of the yamazumi board beyond on-line processes. In the production control area at TMMWV there is a yamazumi board that breaks down in minutes the total time per shift that it takes to load and unload trucks. And Toyota is even targeting such non-standard work areas as equipment maintenance for increased standardization. Their belief is that the more concrete tasks they can pin down and document, the more efficiency they can wring out of their already lean operations.

New and Improved
TMMWV (along with Toyota's new truck plant in Indiana and its upcoming V-8 engine plant in Alabama) represents the second generation of Toyota's manufacturing plants in North America. As such, it exemplifies the company's latest thinking on lean plant layout and operation. According to David Copenhaver, general manager of Administration, "We are more lean than some of the other Toyota North American facilities. We have tried to stretch the envelope a little bit further on the second-generation facilities. We have taken a new look at everything across the line." This comprehensive re-thinking is evident in the plant layout itself. Phil Duncan explains that TMMWV is "Very streamlined and straightforward–we have tried to minimize internal logistics and material handling as much as possible." And these efforts have paid off big time. Launch timing from the beginning of engine assembly operations to the launch of machining operations was reduced significantly over older sibling Toyota Motor Manufacturing Kentucky's previous mark. In West Virginia they did it in eight months for the four-cylinder plant and only five for the six-cylinder plant. Inasmuch as no good deed goes unacknowledged, this efficiency has led to TMMWV's biggest challenge yet: automatic transmissions.

Transmission Impossible
"Because the transmission is without question the most complicated part of the automobile, it is the last thing to be sourced in North America," says Copenhaver, "This being the first time, obviously we have a lot of eyes watching us." TMMWV begins low- volume mass production of automatic transmissions for Camry and Solara this month and plans to ramp up to near full volume of 360,000 units per year by the end of 2001. Though the team members in West Virginia have cut their teeth on a product that requires great precision, making transmissions raises the bar a notch. The number of tiny parts involved in transmission assembly has forced Toyota's managers to focus heavily on ergonomic issues. And the potentially disastrous results of contamination has led to higher cleanliness standards. Duncan admits: "With the transmission, the quality and cleanliness expectations are much higher." This is in part due to the fact that TMMWV is taking the mindset of building Lexus-quality transmissions from the beginning of production, though they will not build a powertrain for the RX300 for another two years.

Toyota's management team in West Virginia has been talking about what Lexus quality means since the RX300 announcement in January. The consensus so far is that making products for Lexus will require further development of the current quality culture, but not a complete overhaul. Phil Duncan quips, "I can't imagine that tolerances can get much tighter."

Toyota utilizes skillets to take its engines through assembly. These platforms allow team members to quickly access any part of the engine. Toyota's Georgetown, Kentucky, engine plant will install this system in the future.

Toyota's Second Generation
TMMWV represents Toyota's second generation of plants in North America. These young upstarts have learned a thing or two from their elders and the result is a leaner production flow.
  • After machining, components go to the interim assembly department where major components like crankshafts, pistons and oil pans are assembled onto the block. These incomplete engines then move on to final assembly to be finished.
  • Castings and forgings are delivered directly to the machining departments. They are loaded into the machining centers by TMMWV team members and then not touched again by human hands until they reach the assembly line. Toyota subsidiary Bodine Aluminum (Troy, MO) supplies castings for the head, lower case and cylinder block; Louisville Forging(Louisville, KY) provides the crankshafts; CWC Castings Textron (Muskegon, MI) makes iron castings for the camshaft, and con rod forgings come from Japan.
  • The final assembly department employs skillet conveyors that allow team members easy access to every part of the engine. Toyota's engine operations in Kentucky will install this system for production of a future engine.
  • From final assembly, the completed engines go to the motoring test department, where they are cold fired to check for defects. The engines are run at RPM levels where problems tend to become audible. The relative quiet of cold testing means defects are easier to hear, and there is no gasoline to drain (or pay for) before shipping. TMMWV is the only Toyota plant outside of Japan to do cold firing.
  • To optimize workload balancing, some operations can be moved between interim assembly, final assembly and motoring test.
  • TMMWV's quality department takes one engine at random every shift, runs it for an hour, tears it down, inspects it for unusual wear and feeds back test information to the appropriate departments.
  • TMMWV can complete an engine in six to seven hours, but actual process time is closer to one full day. This is because anywhere from 1/2 shift to a full shift of engines are regularly held back until quality confirmation results can be calculated.