REV UP Outboard Production

Manufacturing Engineering, Apr 2005 by Destefani, Jim

Rethinking product and process allowed Mercury Marine to

Mercury Marine has been an innovator in marine propulsion systems since its founder developed his first outboard motor more than 65 years ago. Headquartered in Fond du Lac, WI, the company today has manufacturing facilities in Fond du Lac; Stillwater, OK; St. Cloud, FL; Juarez, Mexico; Petit-Rechain, Belgium; and Newton Abbot, UK.

In Fond du Lac, 1,000,000 ft^sup 2^ (93,000 m^sup 2^) of manufacturing space in Mercury's machining and assembly plant is devoted to production of outboard motors in a wide range of horsepowers and other characteristics. Other facilities at the site include a die-cast and lost-foam casting plant as well as propeller manufacturing.

Recently, Mercury launched its Verado line of supercharged four-stroke outboard engines. The only supercharged four-strokes in the outboard market, Verado engines are available in 200, 225, 250, and 275-hp (150, 170, 185, and 205-kW) six-cylinder versions as well as 135, 150, and 175-hp (100, 110, and 130-kW) in-line four-cylinder models.

The Verado engines (see sidebar for details) have raised the bar in outboard engine performance, according to Mercury Marine's Mike Oswald. And, he says, the company felt that such a revolutionary product should be manufactured on a new line, employing automarion where applicable as well as lean manufacturing concepts.

The project manager for the line, Oswald has since transitioned into the role of lean/six sigma black belt. He says the development of the Verado assembly line project was unlike anything Mercury had previously done.

"We approached this development process completely different than in the past," Oswald recalls. "We had program managers for engineering [design] and manufacturing, and we had groups who worked with those managers. Early on, we asked the collective bargaining unit to have some production employees taken off their regular responsibilities to become part of this team. In the beginning, we had three people from production in addition to our engineering, maintenance, and other support groups. So our engineering technicians and production employees built the prototypes together."

Oswald says the cooperation progressed through assembly system design and into prototype, design validation, and production validation builds. "We added team members as needed to help with ergonomic assessments of the line, and other tasks," he says.

The new approach extended to assembly technology supplier selection as well. "Traditionally, we would have designed our assembly processes, then gone out and found a medium-size machine builder or conveyor company to work with us. We would have been the main project leader and integrator," Oswald explains.

"This time, we did a best-practices process-really a worldwide assessment of possible vendors-and wound up choosing Comau Pico [Southfield, MI] as the assembly systems supplier," he continues. "They had the automotive background, and we tried to blend automotive-type assembly systems with our medium-volume manufacturing operation. Our takt times are much longer than automotive assembly takt times, so we had to make sure where we automated or put technology in place that it was appropriate for our volumes. We couldn't put a fully automated line in, and we can't complete an engine every 18 seconds, or we'd over-produce."

Based on an overhead monorail and a system of "J-hooks," the 125,000 ft^sup 2^ (11,600 m^sup 2^), continuous-flow line can produce all Verado engine variants in lots of one, with no changeover. Counting left- and right-hand propeller rotation options, various overall lengths, horsepower levels, and Mercury and Mariner models, there are more than 80 possible variants.

Developed with Comau Pico, the assembly system is controlled by seven personal computers on the power head line and two PCs on the J-hook line. Comau Pico and Mercury engineers also worked together to develop the J-hook and pallet system, which allows operators to easily manipulate the work to the correct height and orientation.

Mercury engineers decoupled the power head line from the final assembly line to enable creation of a power head buffer or "supermarket." Final engine assembly begins when a customer order for a specific model is generated. A barcode for the specific product being built is scanned in on a particular J-hook, and that data follows the engine through assembly to cue each station to the correct process. Seven PCs control the head and block line, while two PCs control the J-hook line.

The engine midsection, held on the J-hook, meets the head and block line for power head mating. This is followed by supercharger and electrical assembly, fuel and air systems, and attachment of the gear case. After filling with oil, the engine then is subjected to cold and hot testing. From that point it's a matter of adding cowling, decals, and other final assembly items.

All fasteners used in the engines are installed using DC digital tools. "There are no pneumatic tools on the line for assembly-there are one or two for other purposes," Oswald says. "Using DC tools allows us to capture an electronic signal to provide immediate feedback to operators, and it reduces noise on the line tremendously-with pneumatic tools, no matter how hard you try to fix leaks there's always noise."