Flexibility: AM General

Better known as Humvee, AM General’s High Mobility Multipurpose Wheeled Vehicle (HMMWV) has served the U.S. Armed Forces for 20 years. AM General, which has built more than 175,000 of the vehicles, began producing a commercial version of the Humvee, called Hummer, in 1992.

In 1999, General Motors acquired ownership of the brand and established the name Hummer H1 for the commercial vehicle. Both the Humvee and Hummer H1 are assembled at AM General’s plant in Mishawaka, Ind.

GM and AM General began an ambitious initiative to produce a “next generation” sport utility vehicle, the Hummer H2. “The goal was to design, engineer, and start assembling the vehicle in less than two years, which is unprecedented in the automobile industry,” explains Tim Kurtz, manufacturing systems coordinator at the Hummer H2 assembly plant.

“To meet the goal, we had to run many of the processes simultaneously,” which included designing the vehicle and the plant, and establishing lean processes and systems, he explains. Built adjacent to the Humvee plant, the new plant is site-restricted. “We had to optimize by using just-in-time inventory because space is very limited,” Kurtz explains.

The AM General team considered various technologies for tracking and managing parts—such as GE Fanuc’s Cimplicity Tracker application, and wireless technology from WhereNet Corp.—that were in place at other vehicular assembly plants. “We made our IT decisions based on cost and flexibility,” Kurtz says.

AM General uses two integrated GM systems at the plant—an inventory management system, and a flexible scheduling system. The company uses the GE Fanuc application to track work in process; the WhereNet wireless parts replenishment system enables assembly-line operators to request bulk material replenishment.

When supplies of a part begin running low, the line operator presses a button on a dedicated WhereCall “pendant.” Each part is identified with a particular pendant, which resembles an automatic garage door opener. Some stations may have as many as five to six pendants, depending on the parts used there.

Pushing the button on the pendant sends an alert to a forklift driver who travels to the dock location, picks up the part, delivers it to the line, and confirms that delivery has been made. All that information is recorded in a database, which AM General uses to analyze throughput and efficiency.

The Hummer H2 plant today is a showcase of lean manufacturing. AM General typically has no more than two hours of materials and parts at any point along the assembly line. Staging areas hold no more than four to eight hours of replenishment inventory. In this type of situation, just-in-time sequencing of parts is crucial—and so is flexibility.

“A new model is introduced every year, so we move parts around to rebalance the line,” Kurtz says. “New parts are added, and others go away,” which requires programming changes. When the 2005 Hummer sport utility truck was introduced, for example, some 110 to 120 new parts were added.

AM General was able to rebalance the line over the course of a weekend—without any production downtime. Because the technology supporting the parts replenishment system is wireless and fairly straightforward, “we don’t need highly paid programmers or a specific skill set to update it,” Kurtz explains.

“We’re looking at using this technology for some new products,” he says. This will give AM General the ability, for example, to handle a significant increase in customer options, sequencing the parts to the right work station, and “matching the right part to the right truck as rapidly and in as lean a fashion as possible,” says Kurtz.