For a few years now Honda and Toyota have been playing a quiet game of one-upmanship as they work to update plants for better efficiency and productivity. The lynchpin for both makers are body shops that replace inflexible hard tooling with robots capable of quickly adapting to build new models. The potential rewards of these efforts are huge. Randy Shiplett, project leader for the recent renovation of Honda’s Marysville Auto Plant in Ohio, says that one goal of the project is to reduce future new model exclusive investment by 50. Another is to cut in half the development time needed after final stamping die designs are kicked off (a point of no return known as “die go” in Hondaspeak), which could reduce overall development time by several months. Similarly, Toyota Motor Manufacturing Kentucky’s vice president of Manufacturing, Don Jackson, says that the new “Global Body Line” (GBL) at the Georgetown plant should reduce investment by 70% for future new model changeovers while halving both energy and maintenance costs. It has already slashed the ramp-up period for the Camry from three months to three weeks. And as for development time, Jackson says, “With this concept in place we can reduce our lead time to whatever the suppliers can support.”
Both automakers began globally implementing their body shop visions in the mid-90s and have almost completed the conversion of their major plants. Honda has either refurbished plants to coincide with the introduction of a full model change, or built the new system in from the get-go in new plants like Honda of Canada Manufacturing’s light truck plant and Honda Manufacturing of Alabama. Toyota says that 30 of its 34 body lines have been converted to GBL. Its truck plant in Princeton, Indiana, which makes Tundra pick-ups and Sequoia SUVs, and will soon add a re-modeled Sienna minivan, is currently being updated. And Toyota Motor Manufacturing Canada will have GBL in place for the launch of the Lexus RX300 next year.
When Toyota began developing its Global Body Line it wanted a system that could work in all of its plants–from labor-intensive, very low-volume facilities to high-volume giants like Georgetown. To make that work it had to make a fundamental change in the way its vehicles are welded together. In the past, heavy, complicated jigs clamped panels and essentially surrounded the vehicle frame as it was welded together. This method reduced the amount of maneuvering space automated welders could use, which lead to fewer welds per station and, consequently, more weld stations. It also required a cumbersome circulating pallet system in which both the palletized vehicle body and its surrounding jigs moved together from station to station. Production flexibility was reduced because each body had to have its own specialized pallet and the weld shop could only store 50 pallets.
Under the GBL system, the outside jigs are replaced with one master jig, which has all of the specialized tooling needed for a given body style, and is lowered through the top of the frame, holding the panels from the inside. This approach not only eliminates the pallets and the heavy transfer system needed to move them, but increases the number of different models that can be produced from five to eight. Coupling this with the use of more precise electro-servo robots has allowed Toyota to double the number of welds per station at Georgetown and reduce the length of the line by half.
To add more flexibility to its body line, Honda decided to lose its backbone. That is, the old layout of the weld department at Marysville was described as a “fishbone” approach in which ancillary processes were physically connected to the main welding stations. This created a direct flow of components that was efficient for mass producing a few models, but hampered the introduction of new vehicles. The new layout is modeled after a jellyfish, where the sub-processes still lead up to the main welding area, but are not connected, giving each area more freedom to introduce new components without affecting final production.
Like Toyota, Honda’s old body shop relied heavily on hard tooling that was expensive to build and difficult to adjust. For example, the “general welder,” where all of the major exterior panels are brought together, could easily experience 30 minutes of downtime for a minor adjustment. Under the new system, robots can be re-programmed in minutes and, since the lines now have standard configurations and equipment, programming only has to be done on one line and then transferred to the next. Tim Downing, engineering project leader for the 2003 Accord, says that the ability to transfer programming “saved a tremendous amount of time” during equipment maturation, and helped lead to the fastest and smoothest new model launch in Marysville’s history. He goes on to say that, “The ultimate goal is to program the robots once for the whole world.”
Though neither Honda nor Toyota will put a price tag on their body shop projects, its not likely that such a thorough re-working will be paid back within just one or two model changes. But once it is, the lower cost of production combined with speedier new model introductions should continue to keep the two companies in a class where their main competitor is each other.