I went down promptly at 6 and spent two full hours there eating and getting to know my companions a bit better.
Then first thing on the agenda was boarding the bus to Nissan's main assembly plant in Oppama. Here, Nissan manufactured the LEAF along with several other models but not side by side. The build order is based on customer orders and is built in the order received. A look down the line would show the different models intermingled on the line. Rarely would two of the same models be consecutive on the line and if that were to happen, the odds of both having the same trim package was very rare. This created a huge logistical challenge of having the exact right part matching up with the exact right car. Each vehicle had a sheet complete with all options and the customers name taped to it to reduce any confusion
In fact, the one thing that was very clear in the plant tour was the level of coordination in the plant between the workers, the line and the multitude of vendors. The plant puts out a vehicle in just over 70 seconds during its two shift 6 day a week operation. Despite being small in size compared to other auto manufacturing plants of its volume, they are still able to maintain a high level of efficiency with the limited space while implementing continuous improvement which they called "Douki-Seisan" method. It is just one part (a very important part) of NPW (Nissan Production Way) that has brought the company from near bankruptcy less than 15 years ago to its current position as a global leader in the automotive industry.
After the order comes in, the sheet metal stamping plant punches out the various body components 4 days in advance. The components are then coated, painted, etc. and then shipped to the factory. They take up so much space that they simply cannot build them farther ahead of time. The rest of the components that go into the car that must be built from scratch have no more than a two day lead time. Here is a LEAF that has already gone thru several assembly stations
The line is supplied in lots of 4 orders at a time by an automated system run by "Carrybees" which are guided electronic robot trains. They are programmed to supply the right part to the right station at the right time. I watched one as it dropped off 4 trays filled with interior door trim to a station then make its way back to an automated storage rack system where it picked up its next 4 components and then it headed off to a different station with a different set of parts. All done without any human intervention at all. Pretty cool! Now, they all play music and sounds more like an ice cream truck than a freight train but they still get the job done!
Worker removing tray from Carrybee
The only component that must be built farther in advance than the 4 days is the LEAF battery pack. The battery pack is installed at the gas tank installation station and is a quick and simple 4 bolt procedure to install with a few cables to attach.