GEORGETOWN, Ky. -- You wouldn't think it to look at the cars side by side. The Toyota Camry and its new gasoline-electric variation, the Camry Hybrid, look much the same.
But slipping the new hybrid version - Toyota's first North American-made hybrid vehicle - into production on the same assembly line as the Camry in Georgetown, Ky., is no small feat. The Camry Hybrid, which begins production this month, is more complex than the regular model and requires radically different parts. Toyota had to find a way to pare line-side assembly parts to a handful at a time and adjust line speed to accommodate the extra time needed to install the parts.
That meant tinkering with the revered Toyota Production System. Changes are not taken lightly. What works in one Toyota factory must work in all.
"Minomi is a big reason we were able to do this," says Dave Cox, Georgetown's general manager and project engineer for the Camry Hybrid.
Minomi is Japanese for "part only." It is a new evolution of the just-in-time world of Japanese auto assembly, where colored kanban cards traditionally have signaled parts delivery technicians to bring in another box of parts.
Normally, such delivery crews would bring a 4-by-4 box to the line worker. Instead, the same crew now wheels a rack of parts that might be just 10 inches wide. The rack might have just two stamped metal parts standing upright on a fixture, like a display of hors d'oeuvres on toothpicks. And behind them on the same rack, ready for plucking, stand the next two parts, and so forth. The supply will last only a few minutes, and then a delivery crew will rush over another rack.
The plant is working with outside suppliers to load their parts into minomi cartridges. The small batches will flow off delivery trucks and straight to the assembly line every few minutes.
Ask Georgetown's managers why the term is Japanese instead of English, and they will admit they're not sure. The concept was developed by a small team of Kentucky engineers, assigned by Toyota Motor Manufacturing Kentucky Inc. President Gary Convis to go to Japan to solve a problem.
Lot of scurrying
But can this really be efficient for a company obsessed with eliminating wasteful activity?
Cox says there now is a lot more traffic moving up and down the aisles of Georgetown, delivering the small batches. But the bigger issue was space.
By replacing 4-foot boxes with 10- to 12-inch racks, Georgetown compressed the space required on the assembly line for various jobs. By switching several consecutive line jobs over to a minomi approach, Toyota freed large stretches of the Camry assembly line. Because the vehicle is moving, that extra space created extra time for team members to take on the more complex and time-consuming jobs associated with building the hybrid sedan.
Among the jobs were installing:
- More than a dozen new floor bolts that hold the hybrid's high-voltage wires in place
- The car's power inverter
- A more complex fuel tank that has a smaller fluid capacity than the regular Camry's but has several different connections
- A large battery in the car's trunk.
There also was an issue of timing. Part of Toyota's efficiency obsession calls for nagara, or an "even flow" of work. The Georgetown plant is like a slow-ticking clock. But that smooth flow is jeopardized by the mixing of vehicles that requires different production cycle times.
Nothing is truly simple at Toyota.