Motorcycle Metallurgy - Why Steel? Aluminum? Titanium?

if I could just see a truly naked motorcycle I'd know the answer [Music] [Music] the frame is not designed to be strong it's designed to be stiff if you ask an engineer to draw precise handling they'll draw a stiffness driven structure Young's modulus is the concept we need it describes stiffness as stress versus deformation the weird thing is that when I divide by density the specific stiffness of Steel titanium aluminum even balsa wood they're all the same so frame material shouldn't matter thin steel tubes leave room for other stuff but we could get similar weight and stiffness from thicker aluminum or a Balsa tree trunk stiffily speaking there's no difference until that's impressive it has been done Honda built a carbon nr500 back in 1983 and found neither Tech nor cost prohibitive the issue is predictability fiber thickness Direction layup Myriad permutations make for mysterious performance Honda would spend months fabricating identical frames only to have Racers complain that each handle different in different ways but steel it's just pipes and triangles KTM can predict the result of moving each Weld and can go from raw material to attract tuned replicable part in four days if our steel skeleton is cheapest yet fastest in the automoto GP race then we've begun to build a monster foreign the challenge with piston engines is endurance in this kl250 is expected to survive 200 000 kilometers while assuming a middling 60 kilometer an hour in the middle 4750 revolutions per minute that means the engine must survive very near 1 billion punishing reps and unlike Alex Jones Kawasaki has the honor to pay up success at such dizzying numbers is all about fatigue limit it's the amount of cycles and material can withstand before an unacceptable drop in performance most metals even expensive ones like titanium will steadily decline meaning parts will need replacing and that's okay for high maintenance engines like the rc30 with its first ever titanium conrons but steel is that weird metal with no fatigue limit and as long as the engine stress is below this asymptote steel is Immortal and no wonder are Conrad is steel the crankshaft to seal the flywheels steal the wrist pin is steel only our piston is aluminum because it must reverse Direction at 7000 G in a heavier metal would pull itself apart and the cylinder sleeve is cast iron but that's even cheaper see galling is when a metal slides smears and welds itself to another and because these piston rings will travel 256 000 kilometers against the cylinder in their lifetime we need the lowest galling metal cast iron conveniently iron can even be re-board to resurrect a whole new life cycle and when the optimal metal is also the cheapest we have something properly dangerous [Music] [Applause] [Music] weight savings improve handling more here than anywhere my suspension is faster pushing a light wheel into traction and I'm faster turning a light gyroscope but Carbon wheels are like hair implants the fact that you can knit a dome into existence is futuristically cool until you remember there for middle-aged men with too much money see Pro Racers do not and cannot use carbon wheels not since 1984 when Freddie Spencer's Rim detonated so catastrophically HRC boss yochioguma had to walk the stands and beg Spectators to return the shards of carbon they snatched from the air Honda finally pieced together what went wrong turns out carbon has high Notch sensitivity the tendency for an otherwise strong material to completely fail when nicked what's annoying on the blue line is fatal on the red line especially since Pro Racers change tires constantly so sooner or later they will ding that carbon Rim but what if we could get nearly as light with cheap Metals just by clever processing where casting is pouring liquid metal into a grain potpourri forging is pressing that metal into its final shape with the grain pattern to match even aluminum when forged can be designed as thin as 7.7 kilograms for a set and that's within 10 percent of the carbon chinaware so it's quick and unkillable now computer numerical control Machining takes a Billet of aluminum and cuts away everything that isn't the part A subtractive process you wouldn't see and see anything large because liquid casting preserves more material and you wouldn't see and see anything strength driven because forging gives tailored grain but CNC is suited for slight High Precision objects like this Henson safety razor which sponsors our video pre-pandemic Henson was a Canadian Aerospace machinist so when the world stopped they were sitting on the equipment to machine blade exposure down to 0.03 millimeters meaning the Razer cannot burn too deep and it cannot bend in Jitter causing cuts Henson even anodizes rather than painting or plating because they wouldn't risk a top coat compromising their insane tolerance this is an excessively well machined razor I like how comfortable it leaves my face but mostly I get a giggle out of using a satellite grade object at 6am use the promo code fortnite to get 100 blades free [Music] foreign you know that sick feeling when you're tightening a bolt and it just stops getting tighter metallurgically I've exceeded the Bolt's yield point aluminum has a yield strength of just 250 megapascals titanium and steel are both stronger at 800 but if an ALU bolt weighs 5 grams titanium is 10 and steel is 20. so okay aluminum bolts for my body work and for the rest titanium but then I remember galling and how titanium Galls pretty bad So Thai bolts must be coated in anti-seize that's a bit precious nut polishers will say it's worth it because titanium doesn't rust but who cares galvanic corrosion is the culprit that matters it's caused by the minute electric current traveling between dissimilar metals from the more anodic to the more cathodic sure titanium Heads Stay blindingly devoid of surface rust but its galvanic corrosion between my aluminum cases and the threads of my bolt metal that gets them stuck and on the galvanic series titanium is more dissimilar to aluminum than steel So Thai bolts cause more corrosion seizures the pursuit of performance keeps bringing me back to cheap Steel oh this feels like steel tea last principle steel is five times less thermally conductive than aluminum meaning the welds cool slow giving hydrogen bubbles time to escape and sealing off all porosity it's perfect for gas tanks but looking at my own bikes I see aluminum tanks they heat up and cool down faster causing condensation buildup and freezing my thighs and they cost more I see plastic tanks they vaporize gas straight through bubbling stickers and aging brittle and they cost more just in this garage I see aluminum frames Nike so bores magnesium Wheels titanium Fasteners and I realize I'm the monster not for creating this 40 year old steel that costs 500 and has the power to weight of a Ford Raptor but for helping create a world that asks for more foreign

Channel: FortNine

Views: 735,799

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Id: ah7Ubbq5EAA

Length: 10min 2sec (602 seconds)

Published: Tue Nov 01 2022