John Deere: Nothing runs like an AGV
Automatic guided vehicles engage specially-designed frames to transport cabs through the assembly process.
A better mouse trap
Deere investigated several different solutions before choosing AGVs. These included an overhead handling system, an old-fashioned chain drive assembly line and even going back to a manual push line. At least with the old system, an operator could push a cab out of the way to fix a problem rather than shut down operations.
Then the Waterloo group learned about an AGV spec that had been designed for Deere’s line of harvesters in East Moline, Ill. “There is a lot of commonality across our cabs and we like commonality across our factories,” says Olson. “East Moline also had a no fault forward policy and their spec had the necessary line speed and weight specifications for our facility. We jumped on board.”
The AGV design Deere chose is a tugger vehicle known as “a mouse.” The “mouse” is designed to go under the load, engage the dolly with a pin and then tug it along. Since there is no longer a conveyor on the floor, an operator can walk completely around the cab itself.
The mouse features a low profile base that rises just 8 inches off the floor and shares the same footprint as the dolly that carries the cab. The total load from the shop floor to the bottom of the cab is just 12 inches. At that height, the roof of the cab is accessible to an operator without a ladder. The step up from the ground into the cab was a normal height. These features both brought a level of ergonomics to the line. “There are certain stations that require additional height,” Olson says, “but we address those with lift tables.”
The vehicle navigates by following a magnetic tape on the floor: If the line needs to change in the future, Deere can simply move the tape.
Deere was also attracted to the mouse vehicle because it was a mass-produced product and not custom-made. If Deere needs another vehicle, it can simply place an order.
Finally, a systems integrator was available with the experience to integrate the AGVs into Deere’s existing production line. “We needed a design for the dolly that carries the cab, we needed to modify the ergonomic lifts and the vehicles needed to communicate with the existing systems over the Ethernet,” Olson says. “We did not have that expertise in-house. The fact that our supplier had an experienced integrator made this a full package.”
The new system went live on Sept. 17, 2010. Prior to the implementation, Deere gathered a team of technicians, management and assemblers to take ownership of the project. Still, management and the skilled trades group at Waterloo saw a test run of the new system to allay any reservations. The supplier brought in an AGV that picked up a cab, ran a loop and then dropped it off at a staging area, just like the mouse would do once it went into production. Seeing was believing. “I’m sure that our skilled groups and management were skeptical,” says Olson. “Once they saw the system do what it was designed to do, people were excited.”
In the year since going live, there has been a reduction in labor associated with moving the cab from one station to the next.
More importantly, Deere is now able to adhere to its mistake proofing policy without shutting down the line: If an error is discovered, the AGV carrying the cab with a fault will stop, while the cabs behind and in front of it continue to move forward.
And, the vehicles have brought a new level of flexibility to Deere. “Not that long ago, we did a project over a weekend that allowed a cab to go to five different testers instead of two,” Olson says. “It was me, a couple of electricians, the integrator, someone from factory automation and some magnetic tape. We could not have done that with a conveyor.”
Having worked with AGVs for the last year, she adds, “We are looking at where else we can use them and there are several other projects in the works,” Olson says. “This has been a stepping stone for us.”
Automatic guided vehicles move tractor cabs through the production line at John Deere’s Waterloo plant.