Mercury Marine
There is nothing like the freedom of speeding across water toward a distant horizon, the boat’s wake behind, and the wide open sky above. That’s what Mercury Marine is all about. The US-based company builds high-performance marine propulsion systems for boat lovers worldwide. Die casting plays a key role in producing the parts to withstand fresh and saltwater environments. The company depends on Bühler die-casting technology to produce engines that are fun, fast, and reliable.
Janet Anderson, November 2024
Wherever you go in Wisconsin, you are never far from water. The state is speckled with more than 15,000 lakes – and the locals know how to make best use of them. A favorite pastime during the glorious summer months is boating, whether for fun, fishing, or just to go fast. Everywhere you look you see boat dealerships, boats on trailers, and boats in the water, often with several outboard engines hanging off the transom. These are people with a true passion for water.
It’s a passion shared by Mercury Marine, a leading manufacturer of marine propulsion systems. Its headquarters are in Fond du Lac, a small town on the southern tip of Wisconsin’s largest lake, Lake Winnebago. The company prides itself on the performance, reliability, and efficiency of its products. And they know all about fun – no wonder their engines sound so impressive when they start up.
Mercury Marine is one of three major players globally and the only remaining outboard manufacturer in the US. Its market strength is built on strong design and manufacturing practices as well as continual process optimization. Reliability is a big selling factor – after all, it is not just the initial purchase price that matters to customers, but the total cost of ownership. The engines are tough and dependable, and that is, to a large extent, thanks to the way that key parts are cast.
Casting takes place at Plant 17 of the Fond du Lac site. This is the home of Mercury Castings, the company’s business unit dedicated to die-casting technology. Inside are rows of automated die-casting cells producing complex aluminum castings. A robot ladles molten aluminum into the die-casting chamber. The temperature inside is 1,260 degrees Fahrenheit (682 degrees Celsius). Among the heat and steam lie massive dies and racks of completed parts, quality checked and ready for the next operation.
With over 60 years of experience in high-pressure die casting, it is a hub of innovation. The Mercury Castings experts are continually experimenting and have developed special aluminum alloys that are tougher, more corrosion-resistant, and have a higher proportion of recycled material to minimize environmental impact and cost.
As well as the alloy, the machines on which the castings are made also play an important role. “Three things matter in die casting: alloy chemistry, die innovation, and the machine,” says Scott Hansmann, Project and Program Manager at Mercury Castings. The company has put its faith in Bühler die-casting machines since 1968, provided by Bühler’s plant across Lake Michigan in Holland, Michigan.
Whichever direction we go in, we look to partner with people like Bühler to continue to innovate and do what we can to succeed in the future.
Scott Hansmann,
Project and Program Manager at Mercury Castings
The first machines purchased by Mercury Marine were smaller toggle machines. In the 2010s, the company was looking at casting bigger parts and in 2017 made an investment in the biggest die-casting machine at the time in North America – Bühler’s 4,500 US-ton machine with 40,000 kilonewtons (kN) of locking force. Then in 2019, they decided to go to the next level of technology as they needed highly controlled process steps. Working closely with the team from Bühler, they made the move to the two-platen Carat. “Today we have 25 die-casting cells ranging from 900 tons with 8,000 kN of locking force, to 4,500 tons with 40,000 kilonewtons (kN) of locking force,” says Hansmann. “The move to the Carat series has been a major boost. It has fewer moving parts, which means less maintenance and improved uptime.”
Mercury Castings sees itself as a high-production job shop. “We cast a large portfolio of parts ranging in size from 5 pounds [2.3 kilograms] to 165 pounds [75 kilograms], including bearing housings, bedplates, the propeller, and engine blocks,” says Nathan Peplinski, Process Engineering Lead at Mercury Castings. Many of the castings are similar in shape but different sizes and weights. Bühler’s Carat series provides the flexibility Mercury Castings needs to make these parts. “The Bühler Carats allow us the ability and flexibility to cast several different products within one cell.
The Carat’s flexibility has enabled us to utilize the best thermal management techniques to successfully balance our various tools to ensure the best possible casting,” says Peplinski. The V block portfolio for Mercury’s large outboards presents some unique challenges. “We cast the engine blocks on our largest die cast machine with 40,000 kN of locking force. The V12, our big-gest engine, is a 165-pound [75 kilogram] shot – that’s a lot of material to manipulate through one cell,” Peplinski explains. The goal is to fill the massive die as efficiently as possible. Shot control and monitoring makes all the difference to repeatedly cast quality parts. “Minor process deviations can have devastating effects on casting quality. Bühler machines provide the visibility to such deviations to our process and allow us the control to quickly overcome any process variation,” says Peplinski. “We are always striving to be better. The level of control provided by the Bühler die casting machines drives our ability to compete as a world-class die caster.”
A major step toward improved processes began just over 20 years ago, when the company started introducing automation in the die-casting cells. Several of the machines are now served by five robots each. The robots pour the molten aluminum, extract the casting, maneuver it through the next process steps, and clean the die ready for the next cycle.
“We used a lot of the features that Bühler provides to develop our processes. They worked very closely with us on this,” says Hansmann. The resulting choreography is impressive. Once the casting is made, one robot extracts it from the press and hands it to a second, which removes the runners and overflows before placing the part in a case where it is laser-marked with a QR code for later identification and traceability. The first robot then picks up the part and places it on a conveyor belt to present to the human operator.
Safety is paramount every step of the way. Next, the part is taken to quality control. This is another fully automated process to check that the dimensions in key areas meet the product specifications. It then goes to machining, paint, and final assembly.
We cast the engine blocks on our largest machine with 40,000 kN of locking force. The V12, our biggest engine, is a 165-pound shot – that’s a lot of material to manipulate through one cell.
Nathan Peplinski,
Process Engineering Lead at Mercury Castings
“Innovation is at the forefront of everything that we’re driving for at Mercury,” says Clay Rasmussen, Technical Specialist at Mercury Castings. “We are always trying to push the envelope on new technology or abilities.” Over the past few years, Mercury Marine has launched a new engine nearly every year. Each new design has between five and 10 different castings in it. The castings have evolved from chunky blocks of aluminum to thin-walled, sporty, lightweight castings.
“A new technology that we are pushing into is electrification. We recently launched a lower horsepower fully electric outboard,” Rasmussen explains. “We drew on our expertise from higher horsepower combustion outboards to make the leap into this new and exciting market.”
Rasmussen works with the product development group to ensure that new designs can be cast. To do this, he uses simulation technology to envision possible defects before the tools are made. For new designs it is also necessary to think through the process on the machine. Again, Bühler machines provide flexibility and reliability. “There is never a second thought about whether we’re able to make even very intricate, large castings in the machine. There are zero issues with integration,” Rasmussen says. “It means there are no limitations to the design we come up with. We have full rein.”
Bühler also provides the services needed to support the introduction of innovative designs. One recent challenge involved integrating the ability to insert liners into the engine blocks. Cast iron liners make the cylinder more stable when the pistons ride up and down. The Bühler team assisted with retrofitting one of the newer die-casting machines to do this. “When we made the V10, we decided to save machining time by putting the liners into the die. We had to develop that whole process,” explains Grant Wollersheim, Controls Engineer at Mercury. The robot places the liners in the die before the shot is made. When the machine opens after the shot, the liners are in the cast part. “One challenge was to design the robot gripper because we had to get it into a tight area and make sure it was pushing straight. My counterparts at Bühler knew their side very well. Their support was a great benefit,” Wollersheim explains.
Mercury Marine is recognized in the die-casting community in North America for their innovation and for being a technology leader. At the North American Die Casting Association (NADCA) they sit on the R&D committees and have a significant technical impact on the industry. Bühler also sits on these committees and works with Mercury Marine to continually develop new ways of optimizing the die-casting process. “Our partnership works well because we share a passion for innovating in the die-casting market,” explains Kristopher Hoffman, Project Manager at Bühler. “We have great respect for their expertise. They were able to engineer and introduce a V12 engine into an outboard engine, which just a few years ago was unthinkable.”
For Steve Jacobson, President & CEO of Bühler West Michigan, it is a collaboration on innovation. “We feel that we’re a good match because we have a similar attitude to innovation and quality. It’s the ability to do something that others thought was never going to be possible or impossible at a certain price. And with Mercury Marine’s engines, the end result is cool and exciting – 600 horsepower hanging off the back of a boat is something you gravitate toward.”
There is no resting on their laurels, though. In every project, the Mercury Castings team always looks for lessons to learn and further improvements. “Bühler is very participative in that respect, because there are things we can do better and Bühler can do better. That close collaboration is what has got us where we are today,” says Hansmann. “Whichever direction we go in – whether it is developing bigger marine propulsion systems to go faster or electric engines for clean, quiet power – we look to partner with people like Bühler to continue to innovate and do what we can to succeed in the future.”
We feel that we’re a good match because we have a similar attitude to innovation and quality. It’s the ability to do something that others thought was never going to be possible.
Steve Jacobson,
President & CEO of Bühler West Michigan
Who: Mercury Marine
When: Founded in 1939.
Where: Fond du Lac, Wisconsin, US
What: Mercury Marine manufactures 75 through 600 horsepower production engines designed for the marine environment.
Customers: The company supplies customers in the US and across the world.
Bühler: Mercury Castings has 25 die-casting cells ranging from 9,000 to 45,000 kN locking force, including the Carat 180L and 280L. It uses the Bühler machines to cast all sizes of components, from the propellers and gear casing to the V blocks for its powerful Verado series.
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