Since 1996, the Plant 15 machining operations at Mercury Marine have included a reliance on automated machining cells. Over the years, the Fond du Lac, Wis.-based manufacturer and distributor of marine engines, parts, accessories and integrated systems has phased out some traditional manufacturing methods in favor of modern cells that provide significantly more production flexibility to adapt to constantly evolving business priorities and customer needs.
The company, which produces both inboard and outboard boat motors, is vertically integrated and manufactures virtually all of its core components, except for those it gets from outside suppliers. Mercury Marine considers itself a high-volume parts producer, with part families consisting of core components such as cylinder blocks, adapter plates, drive shaft housings, gearcase housings and others. Within each product family, parts are segmented by motor SKU type and horsepower range.
Without the automated cells, Plant 15 would have all stand-alone machines with an operator at each to produce its core motor components. Automated cells allow the plant to have one operator running multiple machines, eliminating the need for an operator to manually move parts from one machine to the next.
“Plant 15 would need a significant increase in setups and fixtures without the automated cells,” said Richard Close, manufacturing engineering manager at Mercury Marine’s Plant 15. “Machine utilization would also be a lot less due to available run time from performing changeovers on stand-alone machines.” Another benefit: the use of automated machining cells allows Mercury Marine to focus recruiting and training efforts on other, more labor-intensive manufacturing operations as part of its ongoing growth strategy.
The first automated palletized machining cell at Plant 15 was for four gearcase part numbers. That line, which is still running today, consists of five horizontal machining centers (HMCs) that complete parts in single setups—and basically do the work of the 50 individual machines the plant previously used. The line has also improved part tolerances significantly.
Plant 15 now has 12 automated palletized manufacturing lines plus two robotic cells and a total of 98 HMCs. Mercury’s automated cells and machining centers are PALLETECH Systems and HCN HMCs from Mazak Corp., Florence, Ky. In fact, Mercury is Mazak’s largest user of PALLETECH Systems.
Compatible with Mazak’s range of horizontal machining centers as well as most of its vertical, five-axis and multi-tasking machines, PALLETECH is a modular solution with the flexibility to accommodate most manufacturing requirements, including floorspace, material flow or volume. The system’s pre-engineered, modular design makes it easy for Mercury to add a wide selection of loading stations with capabilities such as wash, tilt and precision centering, all of which allow Plant 15 to pace its capital investments with the growth of its business. In fact, one PALLETECH system accommodates up to 16 Mazak machines, from six to 240 pallets, and as many as eight loading stations.
The majority of Mercury’s HMCs are heavy-duty Mazak HCN-6800 machines that deliver the power and versatility needed for productive and precise large-part machining. Plus, with Mazak’s MAZATROL SmoothG CNCs, the machines provide advanced programming features and functions for ease of use, speed and further enhanced machine performance.
The HCN-6800s have special integral spindle/motor headstocks that minimize vibration and heat generation. They come with 50-hp (37-kW), 10,000-rpm, CAT 50 spindles that deliver exceptional metal removal capabilities in a variety of materials, from steels to nonferrous metals. NC rotary tables on the HCN-6800s rotate 90o in 1.9 seconds and feature 0.001o minimum increments for four-axis indexing and machining. The tables incorporate 360o position couplings and accommodate workpiece sizes up to 41.34" (1,050 mm) in diameter and 51.18" (1,300 mm) high.
Why horizontal machining centers? “If we had a mix of different machines, we would lack the level of flexibility needed to move parts around as much as we do based on volume and commonality to better utilize our available capacity,” said Adam Weidner, lead manufacturing engineer at Mercury. “Plus, most parts are done in only one or two operations and their features just wouldn’t lend themselves well to five-axis or multi-tasking machining systems.”
The number of machines in each PALLETECH cell at Mercury varies from three machines with 10 pallet locations up to those with eight machines and 24 pallet locations. Since incorporating the HCN-6800s, however, Plant 15 has increased pallet storage to as many as 68 in some cells. Most recently, it added about 29 new machines, most of them HCN-6800s, and two more PALLETECH systems. One of the cells has six machines, another has four machines with room to expand to six, one has 10 machines and another houses 14 machines. And there is one Mazak HCN-5000 with an integrated six-pallet changer as well as five other stand-alone Mazak machines in Plant 15.
Within its PALLETECH systems, Mercury runs two or three parts similar in nature or it will mix and match jobs, such as a midsection component running next to a cylinder block, to adjust for changing volume demands. Parts are machined complete, then moved to a finish-and-paint process before moving on to assembly.
“We could be machining engine blocks in the morning that would be installed into a finished motor by the end of the day,” said Weidner. “As our production needs change, we will shift the amount of specific parts being run, but we always try to have each line machining the same product as much as possible. What that does is eliminate time-consuming changeovers. We set up the machines, run a batch of a specific part, then change to the next requirement.”
When the plant does need to adjust the mix of parts and their individual volumes, it does so quickly thanks to its PALLETECH Systems. As new equipment is incorporated, Plant 15 may shift parts from one PALLETECH System to another, which, in most instances and depending on the part, is done within a couple of shifts. All the new systems the plant adds are strictly to increase capacity, replace aging equipment, lower maintenance costs and streamline production, according to Weidner.
“We constantly try to reduce cycle times, and a big part of that is machine utilization,” he said. “The PALLETECH Systems allow us to determine what part mixes to run, then assign each specific priority, thus balancing cell utilization for the highest efficiency.”
Among its automated manufacturing lines, Plant 15 has established what it refers to as service cells and robot cells. The service cells are those that use a three-level PALLETECH system with 68 pallets paired with 300-tool-capacity Mazak Tool Hive tool storage units.
These particular cells allow the shop to maintain its same style of manufacturing with automated cells at the same time that it keeps fixtures ready and stored within the system, eliminating the need to pull tools and/or fixtures in and out of the machines. The plant can then efficiently run its high mixes of low-volume parts. As product lines evolve and change, legacy parts can move to these service cells for machining.
Within its robot cells, Plant 15 uses Mazak machines, but instead of a PALLETECH System, stand-alone robots on overhead rail systems load and unload parts. These parts typically involve multiple machining operations, and volumes are much higher. The robotic cells accommodate up to 18 machines each, which is as many as the gantry system can support.
“Regardless of the cell type, Mercury’s goal is always to shorten response time and lower costs, all while constantly innovating and improving quality,” said David Butcher, category manager–indirect procurement at Mercury Marine. “If we don’t have a capable process, which our Mazak equipment provides, we’re just creating headaches and are unable to run faster. We don’t want to just reproduce what others do; we develop new and innovative products constantly, and the goal is to continue to do so and be the industry leader.”