A different kind of car factory

Saturn revamped an aging GM assembly plant to launch its new mid-size cars and came out a winner.

By -- Modern Materials Handling, 11/1/2000

Saturn advertises itself as "a different kind of car company." General Motors launched the brand in the 1980s to introduce a new philosophy to the American car market, one based on team-building and quick responsiveness to customers. Saturn has grown steadily since then, building thousands of compact cars annually at its Spring Hill, Tenn. assembly plant.

Seeing a need to move into the mid-size market, Saturn first sought to expand operations at Spring Hill before realizing there was a more viable alternative available.

In 1992, GM announced plans to close down its Wilmington, Del. plant by 1996, as it was phasing out the Beretta and Corsica models produced there. Wilmington had a long and distinguished career, producing over 8 million vehicles since its first car, a 1947 Pontiac sedan, rolled off its lines.

"Saturn needed a larger car to expand their market, but it was at capacity in Tennessee," says Tom Brennan, material director. "The Wilmington plant had a skilled workforce, quality numbers, and was cost effective."

GM decided to move the new L-series Saturn production there, but first needed to implement a bridge strategy to keep Wilmington open and the workforce intact until Saturn was ready. The plant built the Chevy Malibu during this interim period while it also started upgrading many of the materials handling systems in preparation for the L-Series, including a skillet system for moving vehicles through a portion of the assembly line.

By the time Saturn production began last year, new power-and-free conveyors had also been installed in the body shop and paint areas, and the skillet system had been expanded to encompass the full assembly process.

But possibly the biggest transition to take place at Wilmington was the result of importing the Saturn philosophy.

"Saturn was putting their reputation at stake by going out of Spring Hill," says Brennan. "We had to have a commitment to quality and responsiveness to the customer."

The same team-building concepts that made Saturn successful at Spring Hill were the basis for the materials handling design at Wilmington. Management and employees joined together to study the facility's processes in an effort to maximize efficiencies by designing improvements into operators' activities.

"Every part of the system was thought out with the operator in mind-the packaging, the orientation, the job layout, conveyors-everywhere possible," says Brennan. "Before, we would not have started designs from the perspective of the line worker."

"It is very process driven," adds Jeff Duncan, materials handling engineer. "We relied on the voice of the operator, then worked from the operations back."

In just a short year, Saturn's way of doing business has firmly entrenched itself at Wilmington with impressive results.

Materials inventory in the plant has been reduced dramatically. The company has also gained a first-in/first-out capability that it did not have before. Injuries have been reduced as well.

To begin, Saturn partnered with a supplier to implement a full returnable container program (Orbis, www.orbis-menasha.com ). In the days of corrugated packaging, lacerations that occurred while opening cartons were the most prevalent injuries in the materials department of the plant. Replacing corrugated cartons with plastic containers eliminates the need for utility knives that caused those injuries.

In addition, walk time for workers has been reduced and double handling eliminated. Lifting has also been limited to an average weight of less than 30 lbs. and a maximum of 35 lbs., about 10 lbs. less than industry averages.

Process-driven facility

Unlike many of the newer car plants that GM builds, no body fabrication or parts stamping occur in Wilmington. Body parts are fabricated instead at facilities in Michigan, Ohio, and West Virginia, then shipped in racks to Saturn. The body shop in Wilmington builds according to a percentage schedule; for example in a given period it may build 85% sedans and 15% wagons. Some of these will be four-cylinder models and others will have six cylinders. A certain percentage will also be built with sunroofs.

Body shop suppliers are sent orders for fabricated materials based on a 2-week planning schedule. Upon arrival in Wilmington, major metal stampings and subassemblies are offloaded from a truck or railcar into a material staging area. Lift trucks then take the parts to lineside presentation equipment, such as lift and tilt devices that help to orient the parts for easier handling. Operators remove the stampings and parts and load them either by hand or with ergonomic assist devices into automatic robotic cells where initial welding is performed.

From there the units are transferred to a monorail system that was added during the Saturn upgrades. After passing through initial processes, the bodies are placed onto skids, which are steel sleds that ride on a large plastic belt. Manufacturing robots weld the various components together throughout the operations.

While in the body shop, a paint tag is attached to the unibody showing the assigned paint color. The units are then transferred to an inverted power-and-free conveyor for travel to the paint shop.

There are seven modules found in the paint area, five are used for normal production, while the other two handle repairs. Several conveying systems operate here, including an overhead power-and-free. This conveyor was previously used in the production of other car models, so Saturn had to modify the carriers to handle the L-Series bodies. Skids are also used in the modular paint area, as are inverted power-and-free conveyors in various procedures, such as the application of a water-base paint and a clear coat finish.

The power-and-free next moves the units to an automated storage and retrieval system (AS/RS), also known as a car stacker, that stages up to 96 car bodies until assembly is ready for them.

While staged, car bodies are assigned to an order. This is an advantage over other plants that assign autos to a build order in the body shop. By assigning orders after paint, Saturn is able to be more responsive to customers by cutting down the time from order entry to completed car.

Pull system for materials

Wilmington is a landlocked facility with roads and neighborhoods on all sides. This does not allow the facility to grow or add storage space. Instead, Saturn has contracted with an outside provider for a 170,000 sq. ft. parts warehouse, located near the assembly plant.

"We have a buffer strategy 8 miles from here where we pool our materials," explains Brennan. "Our goal is to keep 3 hours of materials in the plant."

Suppliers from all over the world send their parts to the warehouse until needed for assembly. Most are stored for less than a day, though overseas parts are buffered much longer.

"The time in the warehouse is directly proportional to the transit time of the part," adds Duncan.

Materials personnel at Saturn are assigned to monitor inventory levels within the assembly areas. When they come upon a station low on parts, the worker scans a bar code that initiates a call for that part from the storage facility. Personnel at the outside warehouse pull the required materials and deliver them by truck just-in-time to assembly.

Some component manufacturing is also outsourced to nearby facilities. These subassemblies must be produced within a short time frame following order assignment. One of these subcontractors is Automodular, the builder of the cockpit. This assembly includes the dashboard, steering wheel, radio, climate system, and other console parts.

"When the car physically exits the paint shop it is assigned an order number," explains Brennan. "That is when Automodular needs to start producing the cockpit. They cannot buffer them because there are so many different component combinations within the cockpit. They literally have to build it, load it onto a truck, and have it to us within 2 hours."

Other subassemblies built locally include the engine, which must be completed within 4 hours, the rear suspension, and the seats. All are delivered in the same sequence as car bodies are released from the AS/RS-stacker.

Most parts, with the exception of seats, are unloaded from the delivery trucks and taken to line-side positions by lift trucks or tuggers. Seats are automatically unloaded onto a conveyor system.

Skillets keep production cooking

Some 1,500 cars are in production at any given moment at Wilmington. About 400 of these are in assembly.

The skillet system used here, as well as at Spring Hill, transports both the car assembly and worker on individual side-by-side platforms. The system reduces much of the walking, saving time and easing worker fatigue. The carrier holding the car can also be adjusted vertically, bringing the job to the proper ergonomic height for the worker.

"From a production standpoint, the skillet is an excellent tool," says Brennan.

Once orders are assigned to vehicles in the AS/RS-stacker, assembly is scheduled. Saturn tries to avoid building two wagons back-to-back, as well as two vehicles requiring sunroofs since assembly processes at various stations to accommodate these options tend to slow down the line.

Cars are transferred from the AS/RS to an overhead power-and-free for the ride to assembly. Upon arrival at the line, the vehicles are transferred onto the skillets upon which most of the assembly work occurs. After completion, the vehicles are transferred to a flat top conveyor for final processes, and eventually driven onto car carriers for transit to dealerships.

New methods yield results

Wilmington's line workers have discovered that the new materials handling systems and the just-in-time materials delivery have made their facility a more comfortable place to work.

"The reduction in inventory has made a much better environment in the plant," says Brennan. "It is easier now to walk around and see people in the aisles and at their workstations."

This contrasts to the stacks of materials that used to line assembly areas, creating "tunnels" of operations between them. Less onsite inventory also allows Saturn to be more flexible, changing parts or suppliers much easier to meet production conditions.

The team concept has also brought advantages. Since workers are involved in planning, there are few surprises.

"There is more ownership now," says Duncan. "Everyone has a voice that is being heard."

The Saturn philosophy also adds the customer to the car-building team. As way of illustrating this point, Saturn invited the first family to buy an L-Series car produced in the plant to spend a week in the facility. This Connecticut family allowed workers to better understand the needs of a typical customer. Brennan says that the experience was memorable and that the family still speaks regularly by phone to some of the workers.

"Our employees now know what it means to be responsive to the customer," he adds.

Benefits at a Glance

• Manual handling reduced

The Story Behind The Returnables Program

Several factors went into designing Wilmington's returnable program. As with other systems, the primary objective was to create a program designed from the operator's point of view. Each step was engineered to consider how parts are delivered line-side, their orientation, and how workers handle them during installation.

MANUFACTURER'S PROFILE

Saturn Assembly Plant Wilmington, Del.

GM production began: 1947

Saturn production began: 1999

Product: Saturn L-Series sedans and wagons

Annual output: 106,000 vehicles

Facility size: 3.2 million sq. ft.

Employees: 2,100-one shift

Miles of conveyors: 15.7

Equipment suppliers:

Plastic Containers:
Orbis, 888-217-0965, www.orbis-menasha.com

Arca Xytec Systems, 800-423-3221, www.xytec.com

Pallets and other containers:
Trienda, 800-356-8150, www.trienda.com

Robinson Industries, 517-465-6111,www.robinsonind.com

Skillet system:
Rapistan Systems, 616-451-6525, www.rapistan.com

Other conveyors:
Fata Automation, 248-553-8181, www.fatainc.com

Southern Systems, 901-362-7340,www.ssiconveyors.com

Monorail:
Acco Chain & Lifting, 800-967-7333,www.accolifting.com

Robotic systems:
Fanuc Robotics, 248-377-7000,www.fanucrobotics.com

Lift trucks:
Yale Materials Handling, 252-758-9253,www.yale.com

Hoists:
Global Manufacturing Solutions, 810-773-4330,www.citationtools.com

Hand scanners:
Symbol Technologies, 516-738-4915, www.symbol.com