Toledo, Ohio is where Jeep military vehicles in 1941 first rolled off an assembly line and headed for the battlegrounds of World War II. Fast forward 60 years to Toledo today and the new Jeep Liberty assembly plant. All it takes is one look around to see that at this new $1.2 billion assembly plant, DaimlerChrysler is creating the latest and most exciting chapter in a continuing success story.

At the Toledo North Assembly Plant (TNAP), 2,000 production employees build the new Jeep Liberty 2002, a sport-utility model introduced this Spring. TNAP is truly a state-of-the-art facility that applies worldwide best practices. These are combined with advanced materials handling equipment and systems to streamline supply chain management and promote the smooth, worker-friendly flow of parts and vehicles throughout production.

Key supply-side strategies for greater efficiency include delivery to assembly of very high levels of just-in-time (JIT) and sequenced parts and a 100% electronic kanban system. Automatic guided vehicles handle racks of parts. And trailer unloading is semi-automated in some cases so that a slug of seats or instrument panels, for example, arrives in one batch, JIT and sequentially.

Additional manufacturing best practices involving improved materials handling include the use of both skillet and "gummiband" conveyor systems. "Gummiband" is the German term for rubber belt. The technology's application at TNAP reflects its benchmarking with Mercedes-Benz operations.

Both types of conveyors provide ergonomic benefits. The scissor lifts aboard the skillet system present work at a comfortable height for assembly line employees, for example. The giant, 7-foot-wide rubber belt conveyor also scores high for its low noise level compared to traditional metal conveyors. And its other benefits include low cost and low maintenance.

With its reach fork design, this automatic guided vehicle handles a rack full of parts to build Jeep Liberty vehicles. A revolving laser beam atop the AGV's mast (above the number 5) guides the vehicle.

TNAP is a lean plant. Almost all (roughly 98%) of TNAP's daily supply requirements arrive JIT or in sequence. More than 900 components for the Jeep Liberty arrive sequentially with 180 deliveries each day.

Sequential parts have to arrive in the exact order needed to build specific Liberty vehicles (by model color, options, etc.). TNAP also is a fast-paced plant running in high gear. The plant is designed to make 800 sport utility vehicles daily on 2 shifts, or 200,000 vehicles annually.

Meshing materials handling systems with incoming parts and ensuring smooth receipt at workstations is the responsibility of Gentry and her team.

"Workstation optimization for our employees is a major focus of ours," she says. That responsibility requires that 400 trailer loads of materials flow steadily and efficiently from TNAP's 66 receiving docks daily to hundreds of workstations. In just the trim, chassis, and final assembly area, there are 344 workstations to be supplied.

"We oversee a high volume of parts going to a large number of relatively small workstations. We also must support flexible, modular manufacturing," she explains.

How are these efforts proceeding? Even though TNAP just reached full production, early results are impressive.

"We've taken materials handling to the next level," says Rick Mazzei, TNAP materials manager. "We truly have a pull manufacturing system, and especially so in our body shop." Nothing comes to the line unless and until the operators ask for parts. "It's all pulled by our operators, not pushed," he explains. And he sees the benefits of investing in improved materials handling and parts sequencing for TNAP.

Materials handling technologies applied at TNAP for high productivity include laser-guided automatic guided vehicles (FMC, www.fmcsgvs.com, 215-822-4300). Among the factors behind selecting these AGVs and this kind of guidance, as Gentry says, is the flexibility this navigation technology provides. Should TNAP's layout and line configurations change in the future, as undoubtedly they will, this type of AGV is easily rerouted.

In TNAP's fleet of AGVs there are 21 vehicles. Fleet size was optimized by computer simulation. Plus there are two spare AGVs serving as backups for any maintenance or downtime needed on the other AGVs over the two-shift operation.

Each AGV has the same reach fork design which enables it to lift, lower, and carry a variety of Liberty parts held in custom racks. "The AGVs handle racks of doors, hoods, swing gates, fenders, and more," says Gentry. They deliver 32 different components currently.

These AGVs interface with 41 automated rack handling systems based on air film conveyor technology. These line feed over/under exchange devices help automate delivery by AGV of racked parts to the body shop and return of empty racks from workstations, also by AGV. Roughly 80% of racked parts are handled by the AGVs.

Similarly, 24 automated dock storage and rack handling systems provide flexible pickup and delivery (P&D) capability. These flow-through systems interface with both conventional forklifts and with the AGVs.

TNAP relies upon an up-to-date information flow to help keep track of all the parallel flows of racks, materials, and parts coming into the plant. Forklifts, for example, are equipped with radio frequency data communications. Operators are informed in real time of the need to move incoming loads to the line or pick up empties, explains Ray Swangstu, TNAP material handling engineer.

Receiving docks, moreover, are tied into TNAP's factory information system (FIS). In this way managers know in real time the utilization status of each of the 66 docks.

"We have constant feedback from FIS on the docks," says Gentry. "This capability enables us to analyze our dock traffic and any issues that may come up." Yard management software also helps in scheduling trailer deliveries.

TNAP's kanban system is fully electronic so managers and operators can track parts supply throughout the plant on their computer terminals.

DaimlerChrysler has a strong environmental focus, using returnable containers at TNAP whenever possible. Container makers must provide reusable packaging so that supplied parts arrive undamaged and are readily accessed from the containers by line employees. For Liberty assembly, Gentry and her team focused on ways to simplify rack designs for parts. The team worked with rack suppliers to eliminate lockoff and tie bar devices where possible and to have racks made with few or no moving parts.

With heavy parts especially, as Swangstu notes, "gravity does a remarkable job of keeping parts in place in a rack."

Simpler rack designs and fewer moving parts in racks have cut down on initial purchase costs. These racks also are expected "to dramatically reduce our rack repair costs – by as much as 80%," says Gentry.

Simpler, more accessible racks also maximize the value-added time of production operators. They spend less time pulling parts from racks, more time on assembly tasks.

Even though TNAP occupies 2.1 million square feet, it's rather small for the auto industry. That's by design. For one thing, instead of 30-foot-wide workstations found elsewhere in auto and truck manufacture, many TNAP work areas measure only 20 feet or even 10 feet in width.

Smaller workstations impact materials handling in many ways, as Gentry explains. For example, there's less room for point-of-use supply storage along the line. That, in turn, pushes needs for JIT and sequenced parts delivery (SPD) supply.

With the relative lack of lineside supply, TNAP makes extensive use of "lineside limos." They are simple methods of parts supply in which components travel with a moving subassembly. A tote box of kitted parts needed for door assembly, for example, may hang on a carrier rack suspended from a power-and-free conveyor transporting a door panel (photo). Parts for the panel are readily accessed. "We have 85 lineside limos throughout the plant," says Gentry.

From Henry Ford's days to now, conveyors have been crucial to any auto plant. TNAP is no exception. But that didn't make their selection cut and dried by any means.

Indeed, as Keith Asquith, advance assembly manufacturing engineer, ex-plains, his DaimlerChrysler team used a detailed ranking method to select among different conveyor types.

For the total of some 3.75 miles of conveyor within the trim, chassis, and final assembly area, the ranking method resulted in a mix of conveyor designs. Inverted as well as overhead power-and-free conveyor, skillet conveyor with and without scissor lifts, belt conveyor, chain-driven live roller conveyor, and overhead monorail are all used.

Skillet conveyor is increasingly seen in the newer auto plants, of course. It won very high rankings at TNAP for such criteria as safety and operator accessibility. It is used on trim lines #2 and #3 and on chassis lines #3 and #4. Indeed, it was clearly the technology of choice by DaimlerChrysler's advisers on ergonomics, Asquith says.

The skillet system's high operating costs had to be overcome to stay within budget, however. By standardizing on an ergonomic operating height for the scissor lifts and slightly redesigning the conveyor system, the cost of the system dropped.

Jeep Liberty vehicles carry on the best traditions of the rugged, go-almost-anywhere Jeeps of World War II. But look more closely at the Liberty and how it's built and there's a world of difference. And the only battles this SUV will likely see will be those played out in parking lots of supermarkets on Saturdays.

Click on this icon to read a case study on DaimlerChrysler assembly of an earlier Jeep model.