If there’s one word that describes industry’s approach to automation today, it’s flexibility. End users want the improvements in productivity, throughput and accuracy that come from automation. At the same time, they also want technologies that scale up or down with the volume of activity in a facility and can adapt to new products, processes and services that haven’t even been thought of today.
Flexibility was a key motivator behind T.E.A.M. Systems’ implementation of 36 automatic guided carts (AGCs; Daifuku North America, daifukuNA.com) in 2013 in the Toledo, Ohio, plant that services a nearby Jeep plant. AGCs are a simplified version of an automatic guided vehicle (AGV) designed to carry smaller payloads. They are guided by magnetic tape that can easily be reconfigured to create new routes for the vehicles.
T.E.A.M. uses AGCs in the assembly of front-end modules for the Wrangler and Cherokee and front and rear bumper fascias for the Cherokee. Parts are assembled and delivered just-in-time (JIT) and just-in-sequence (JIS) with vehicles coming out of the paint line at the auto plant. Depending on the vehicle program, T.E.A.M. has between one and three hours to deliver parts after its manufacturing execution system (MES) receives an order broadcast from Jeep.
The AGCs act as a mobile assembly line: Parts are placed on a carrier and transported from one subassembly station to the next until all tasks are complete. While efficient, the main benefit is flexibility, says Paul Irving, a process engineering manager with Magna, the parent company of T.E.A.M. Systems. “When we began this project,” he says, “AGCs weren’t our cheapest option, but we felt that we could reuse them down the road to create new assembly lines with a minimal capital investment.”
And while automatic guided vehicles and carts aren’t typically thought of as a space-saving play, like automated storage technologies, the AGCs have allowed T.E.A.M. to manage the increasing complexity of auto manufacturing in a space-constrained area. “We went from 12 subassembly stations to more than double that number,” says Irving. “Meanwhile, we have a number of barriers in the plant that can’t be moved, like our shipping conveyor system. The carts provided the flexibility to design an assembly line around those barriers.”
A world-class manufacturer
Magna International, the parent company of T.E.A.M. Systems, is a leading global automotive supplier with 312 manufacturing operations and 83 product development, engineering and sales centers in 29 countries. The company has more than 130,000 employees focused on delivering superior value to its customers through innovative processes and world-class manufacturing.
The Toledo facility was built in 2006 to support the Jeep Wrangler, Jeep Liberty and Dodge Nitro programs. T.E.A.M. has also produced interior components for the Mazda 6, which is built in Flat Rock, Mich., and consoles for Whirlpool appliances in North America. “Everything we do is just-in-time and just-in-sequence,” Irving says.
In a JIT/JIS facility like T.E.A.M., uptime and accuracy are critical. The rule is to never shut down a customer’s assembly line, either because of a late delivery, a quality issue or because parts are out of sequence with the vehicle coming down the line. And, since every plant will have a hiccup now and then, Irving adds, it’s essential “to have contingency and backup plans in place to keep our customer running.”
Complexity, constraints and flexibility
The Toledo facility is a lean and efficient operation. Prior to implementing AGCs, the plant was already working with automation, including a pick-to-light system in the kitting area; bar code scanning to verify accuracy; computers at every assembly station; a shipping conveyor; and a robotic truck loading system. Unnecessary touches had already been engineered out of its processes. For those reasons, the selection of carts wasn’t driven by a need for efficiency or to reduce head counts.
Instead, the AGC project was driven by three key factors: the increasing complexity of automotive manufacturing, space constraints in both automotive assembly facilities, and the need for flexible automation. “The number of options our automotive partners are asking for is on the rise,” says Irving. “Side air guards, which are just one of the plastic components we produce here, have a potential of 16 different configurations that we set up in our kitting area.”
Meanwhile, automotive OEMs are constrained by the size of their facilities, so they are relying more than ever on suppliers to deal with customization and complexity in their facilities before shipping parts to the auto assembly plant. That creates space constraints down the supply chain.
Flexibility came into play in another way: With the frequent introduction of new models and new options, an investment in a new system or technology today will ideally be flexible enough to be reused tomorrow to meet new requirements. And, don’t forget the absolute requirement for accuracy in JIT/JIS processes: automation imposes discipline in processes that drive accuracy.
Prior to the implementation of AGCs, subassembly stations were located on a rotating carousel and one individual stayed with an assembly through each step of the process. When the tasks associated with one station were complete, the carousel rotated to the next subassembly with a task for that component. It was an effective process, which is still used for some products manufactured in the plant. The operator’s name went on the part, which gave them a sense of pride and ownership. What’s more, if the OEM had a shutdown or was slow that day, T.E.A.M. could adjust its build schedule accordingly and continue to operate.
However, with added complexity, the carousel was no longer efficient for some assemblies. Parts were too complex for one person to build all the way through. What’s more, the carousels had to get bigger and bigger to accommodate the additional subassembly stations—one line grew from 12 to more than 24 stations. Some features of the building and permanent equipment, like conveyors, couldn’t be moved to install a traditional assembly line. “The carts allowed us to create an S-shaped assembly line that fits around those permanent fixtures that can’t be moved,” says Irving. “And, because carts are guided by magnetic tape, it’s easy to change a path if we need to in the future.”
Integrating with MES
Because parts must be delivered in time and in sequence, the MES is tightly integrated with Jeep’s manufacturing system as well as the subassembly stations and the cart system.
When a broadcast arrives from Jeep, the first task is to pull the parts that are going to be completed from a buffer of partially built assemblies that will be customized for the order. The system directs operators in manual storage and retrieval systems (MS/RS) and in pick-to-light kitting areas to pull all of the items that will be required. The partially built assemblies are put in fixtures on the AGCs while the kits are delivered to subassembly stations.
AGCs are then dispatched to each of the subassembly stations for that line. The MES and programmable logic controller (PLC) communicate with computers at each subassembly station to direct operators through the tasks that need to be completed. Each completed task is verified electronically; for instance, an operator may scan a bar code label or the system may capture an action, like applying torque to a part.
Once all the tasks at the stations have been completed and communicated to the PLC, the AGCs are released and directed to the next subassembly station for that part. Once a cart has visited all stations, the part is delivered to a quality inspection and electrical testing station.
Parts that pass inspection are then delivered to the shipping dock on specially designed pallets or racks, depending on the part. Pallets are automatically loaded into trailers by robots while racks are backed into the trailer by a tugger or loaded manually. Once loaded, the trailers are delivered to the Jeep plant.
After a year of working with AGCs, Irving says the primary benefit has been the flexibility to make changes and the savings in space. In the future, however, he believes that other benefits will be realized. “We have to keep getting better to stay on top of our industry,” he says. “We really believe this is an investment that we’ll be able to leverage as processes change in the future. We’ve already had other Magna facilities come visit us, and they’re now looking at the adoption of carts.”
Automatic guided carts: Daifuku North America, daifukuNA.com
Manufacturing execution system (MES): Nysus Solutions, nysus.net