Minn Kota Parts

Minn Kota Parts

ENGINEERING Plastics AND Motorboatmotorsalready go together like ducks and water. Because oftheir corrosion resistance and ever-improving structural capabilities, plastic materials have takenthe spot of metal in components both in and out of the engine compartment. Just consider thenewest minn kota from Mercury Marine for the lesson in all of the that plastic materials canperform. The company's 225 to 275 horsepower, six-cylinder Verado motors, the very firstsupercharged four-stroke models inside their class, make use of polymers for their air-intakemanifolds, cam covers, motor control unit housings, resonators, plenums that assist reduce engineduring idle, and the majority of of their fuel modules.

Three surpasses One

Maritime engine covers long ago went into plasticmaterials, mostly single-piece types produced fromsheet shaping compound (SMC) or thermoformedsheet. Verado's new motor enclosure, by contrast,includes three injection-molded plastic cowls. Thetopmost cowl sticks out because of its sheer size.Produced from a 33-percent glass-filled nylon 66, thispart measures 33.5 X 22.9 X 16.4 inches and weighs11.3 lbs. Mercury plastic materials engineer MiteshSheth calls it the "largest injection-molded cosmetic

nylon part on earth," claims that DuPont Engineering Polymers, the content supplier, confirms. Astructural rear cowl created from the identical nylon mates together with the top cowl along adiagonal split line and attaches with an aluminum structural member that joins the engine for themotorboat. A smaller front cowl molded from two pieces of glass- and mineral-filled DuPont Minlonnylon completes the upper motor housing.

A few other molded plastic parts go into the cowl assembly. A PC/PBT air dam cap, which channelsair in to the engine, attaches to the top cowl. As well as the rear cowl features a separately moldednylon 66 structural rib that Mercury attaches by using a urethane adhesive. Finally, the Veradosports a lower cowl to protect the drive shaft housing. Though it's mostly conventional in the style,Mercury engineers chose to mold this lower cowl out from a DuPont Sorlyn ionomer, a type ofthermoplastic recognized for its capability to support high-gloss, molded-colored.

The whole assembly might seem a little complex initially. After all, maritime engine top cowlingshave until recently had simple, single-piece shapes. John Zebley, Mercury's director of model, goesup to now with regards to describe these earlier types as "inverted trash cans by using a seal." Yetusing injection molded plastics and splitting the cowl into pieces worked to Mercury's advantage in anumber of ways.

Reducing cost is a big one. Sheth explains that this nylon components can reach a category A finishwith less paint than the SMC parts. "They have fewer defects, like orange peel, which increases ouryields," he states. And also the lower cowls, making use of their molded-in color, don't need anypaint whatsoever. Sheth estimates that these particular paint line savings give rise to a roughly 46-percent lowering of piece-part costs when compared with SMC.

Weight reduction is another advantage. Tom Walczak, cowling project engineer, reports thattraditional SMC cowling represents up to twenty percent from the entire powerplant weight. At 35lbs, Verado's cowling weighs 30 percent less than SMC. And that savings makes a huge differencewithin an industry that equates performance with power density.

Some of that weight loss comes from the thermoplastic's specific gravity advantage versus SMC.However the style freedom from molded plastic materials contributed with this click here for infoscore as well. Sheth notes that plastic parts have relatively thin nominal wall thicknesses as the SMCparts will have required "bulked up" regions to mold properly. And the injection-molded partsallowed molded-in features impossible within a compression-molded part. Walczak cites the Veradocowling's patented integrated latching system--through which formerly separate hinge mountingpoints, cable guides, and brackets are already molded straight into the most notable cowl, as oneexample. This model, integration saves some weight by eliminating bolted-on latches. Furthermore,it plays a role in a decrease in assembly costs on top of the 46 percent savings in the paint line.

The multi-piece nature of the cowl like-wise furthered some important style goals--ones relevant topackaging the motor and sprucing up its visual appearance. The Verado's straight-six supercharger

and configuration together led to a tall engine. Zebley says the diagonal split line and overall stylingof your cowling combine to "help mask that height." In balancing this industrial styleobjectiveagainst engineering needs, Mercury's engineers and designers worked together right away from theproject and quite often were required to develop compromises. For instance, the engineers wantedto leave some clearance within the engine compartment for air movement. Additionally they wantedto leave some wiggle room to permit relative movement between the motor block, on its mounts, aswell as a cowling that rigidly attaches to the Verado's aluminum mounting structure. Walczak statesthat industrial http://www.dgif.virginia.gov/fishing/ style wound up "tweaking their styling lines abit" to offer engineering so much-needed clearance.

Breaking up the cowling also solved a classicdraft angle problem. Obtaining athin and tall,bucket-shaped cowl from a mold would havebeen almost impossible without adequatedraft. Even a tiny amount of draft might haveflared out the base of the cowl. And that widthwould have interfered with the 26-inchspacing necessary to put more than one motoron the motorboat. "Splitting the cowl made thedraft angle of your individual parts a smalleramount of an issue," Walczak says.

Finally, the split cowling added an importantease-of-use feature. As an alternative tostruggling to lift off a huge, single-piece cowlexternally the motorboat, boaters may nowreach across the top cowl, unlatch it, andremove it from inside the motorboat.

Very hard Material

Apart from its role in dressing the Verado visually, the cowling also has to play a structural role tobe able to protect the motor. MercuryMaritimetypes the cowlings to face up to deflection understatic loads corresponding into a 200-lb person with size 10 shoes standing along with the enginecover. "People shouldn't get in the motorboat that way, nonetheless they do," Walczak says. And alsothe cowling must last to impact loads on every side of the outboard--both below and above thewaterline. One of Mercury's tests involves smashing a fast-moving fake log in the leading side of thesubmerged gearbox, which forces the motor to pivot violently out of your water. This test can resultin 300G impact loads, which ultimately transfer from the cowling components, as outlined byWalczak. So rigorous is this test that this makes a number of the company's other impact testsalmost a formality. "In the event the cowling survives the log test, it survives anything else we throwat it," says Walczak. Ensuring the cowling did survive called for some design intervention since thecowling matured. For Sheth, instance and Walczak added a structural rib on the within the rear cowlto aid tie it towards the motor structure. Mercury glues from the rib using a structural urethaneadhesive that gives them a joint with a lap shear strength of more than 500 psi. Shaping inside therib would not have worked in such a case since the rib's stiffness would have interfered with all theunique ejection system utilized to buy this horseshoe shaped part from its mold--a proprietary"floating island" model from CDM Tool & Manufacturing Company. "The cowl has to flex in the toolto allow ejection from your mold," Sheth says.

The Best Material

An excellent knowledge of material properties also helped the various components meet thestructural requirements inside the face of thermal and environmental factors that usually reduceplastics' working mechanical properties. Sheth was required to account for a number of thesefactors in choosing the right material for the job: The cowling parts experience temperatures asmuch as 230F and also exposure to UV light, salt water,rain and snow, and chemicals which rangefrom fuel to suntan lotion. The demand for a category A surface further complicated the selection."Glass-filled nylon 66 was the very least costly material that was both structural enough andaesthetic enough." Sheth says.

But even picking the right nylon wasn't straightforward given the conditions in which the cowlsoperate. Before picking a material, Mercury engineers performed extensive finite-element-analysiswork on the cowl using ANSYS software. And that work told Sheth that he or she needed a materialwith a flexural modulus of no less than 700 kpsi. Make your h2o the permanent address. A Personrealize what you want from the trolling motor. Minn Kota is actually a workhorse in which dives in inorder to the thick associated with it and functions right after ...That figure does fall well throughoutthe capabilities of reinforced nylon 66. In reality, the grade that Mercury uses has flexural modulusof roughly 1,300 kpsi. Yet Sheth's knowledge about plastic materials told him that this materialwouldn't perform anywhere near that well inside the field. "We needed something with 700 kpsiafter accounting for the impact ofmoisture and heat, and chemicals," he says. "And that's notsomething that FEA will show you." It took extensive material testing to inform him what he did needto know--the 1,300-kpsi grade under consideration will have a flex mod even closer to 800 kpsiinside the engine's actual operating conditions. "That was still adequate for your application,"according to him.

Sheth also put a great deal of effort into controlling and predicting glass fiber orientation from thecowl parts. It additionally influences shrinkage and warpage which could have hurt the fit from thecowl components, though orientation obviously matters for structural reasons. "The shrink at the topand bottom would have to be exactly the same," Sheth says. In the event the fibers go through theresin surface, What's more, the location of the fibers relative to the top of the part can hamper theability to get Class A surface--.

Through the style stage, DuPont performed a mold-filling analysis to see exactly how the fibers linedup from the part under different gating scenarios and molding conditions. At a later time, he dealtwith experts from Mercury's molder, Bemis Manufacturing Inc., and from DuPont to fine-tune theshaping methods and conditions influencing fiber orientation. They decided, for instance, to moldthe top cowl in a sequentially valve-gated tool, that helps manage fiber orientation by controllingfilling patterns.

Keeping Quiet

Another important role to the Verado's cowling involved its contribution to reducedvibration andnoise, and harshness (NVH). Each and every the engine's hushed sound boils down to the cowling."Many things happen to be done right to create this motor silent," says Tim Reid, director of enginestyle for Mercury R & D. He cites a short list to the Verado that includes improved gear qualitywithin the drive train, a nicely-tuned air intake system, the plenum that tunes the idle exhaust, alongwith a resonator that cancels out some of the rotor noise in the supercharger.

But the cowling undeniably helped noiseless things down and offset a few of the noise added by thesupercharger. "Before designing the cowling, noise measurements obtained from early motor

prototypes gave us some concern," Walczak recalls. "Initial noise measurements from the uncowledVerado arrived in more than the noise measurements of a lot of our uncowled competitors."

Yet the design crew didn't just accept a noisy motor. Walczak reports that they can put extra effortinto optimizing the air intake system, for example the geometry in the air dam at the top cowl aswell as the intake-manifold passages. Noise considerations also informed the fabric selectionprocess. Sheth states that he sifted through dynamic mechanical analysis data and asked for soundtransmission tests over a panel samples before purchasing the information to the cowlings. Theirefforts have paid back. "We think we currently possess the quietest motor in the class," saysWalczak.

RELATED Document: And Also The WINNER IS ...

Mercury's cowling model for that Verado took home a pair of model awards with the 2004 StructuralPlastic materials Conference. Its top cowl won the Conference Award for the best innovative entrywithin the conference's design competition. And also the cowl assembly won the People's ChoiceAward sponsored with the Industrial Designers Society of America and Plastics News. For moreinformation on Structural