EVERYTHING about the CRANKSHAFT - Function | Manufacturing | Different types | Forged | Billet

299 really handy so yeah this is exactly what we're talking about today crankshafts as a matter of fact I decided to start a whole new series today and I'm unofficially gonna call it the engine boot camp and in it we're gonna cover a whole range of interesting and important topics so when all this mess is over we're gonna come out of it as smarter petrol heads and we're starting with this the very heart of the internal combustion engine the crankshaft and after watching this video you're gonna know all about different types of crank shafts their disadvantages their advantages how crank shafts are made you're gonna hear terms like crank crank radius crank Rose we're gonna talk about application balancing counterweights you're gonna hear terms like knife edging yeah basically everything you need to know now I'm willing to bet that when you think of a crankshaft you think of well this thing and if she strongly associate crankshaft with internal combustion engines well the truth is that crankshaft are really older than internal combustion engines as a matter of fact they're ancient the first instances of a crankshaft date back as far as 200 years BC in the Western Han Dynasty in China here crank shafts were used to hand operate a worm a fern is a primitive stone tool that's used to grind cereals and various foodstuffs but all crank shafts where adults on the hand operated runs of the Western Han Dynasty or those inside a ten thousand horsepower top fuel dragster have the same purpose they'll do the same thing they convert the reciprocating motion into rotary motion inside an internal combustion engine but after now motion of the Pistons it is converted into rotary motion by the crankshaft and then transferred through the flywheel and the clutch and transmission all the way to the wheels of your car or Marcel this principle of converting reciprocating motion into rotary motion was why do we use throughout history here's something from the Romans as you can see here the rotary motion of the water mill is converted into reciprocating motion via a crank and an actual connecting rod with the end result of sawing logs in half and while the purpose has remained the same the leaps in technology resulted in a massive evolution of the crankshaft from a simple wooden hand operated to to a high precision high strength metal piece of amazing engineering capable of sustaining thousands upon thousands of horsepower and prolonged exposure to very extreme forces [Music] now before we dive deeper into the world the crankshaft first we have to know what is what are in crankshaft so let's get our crankshaft again and let's check it out now all internal combustion engine crank shafts have main journals and rod journals so these are the main journals now the main journals is what the crankshaft itself rotates on and the crankshaft is held in the engine block at the main journals by the main journal bearing caps these journals which are usually smaller than the main journals are called rod journals they're also known as crank pins or big hand journals they're called big end journals because this is where the big ends of the connecting rods are connected the rod journals are connected to the main journals via crankshaft webs now the distance between the main journal centre line and the centre line of the rod journals is called the crank throat aka crank radius and this measure determines the stroke of the engine it determines the up and down distance of travel of the piston the stroke of an engine is always going to be two times the crank draw at the end of the crank shaft the butt of the crank shaft if you will we're going to find a flywheel flange this is where the flywheel is bolted onto the flywheel with its heavy round mass has the task of smoothing out the pulsation of the combustion inside the engine these pulsations occur at different times and without a flywheel the engine would feel much less smooth on the other hand of the crank shaft we have the nose and this is where the crankshaft pulley is attached to these big chunks of metal are the counterweights now the operation of an internal combustion engine generates strong rotational forces and the mass of the the piston pin and rings and the connecting rod moving up and down at high speeds generates a very significant force that is exerted onto the crankshaft the counterweights have the task of balancing out these masses and forces will talk more about cultural rates later in depth video now the holes that you can find in the rod and main journals are oiling holes engine oil is picked up from the sump by the oil pump and sent through the block to the crankshaft the oiling holes on the crankshaft had the task of creating a film of oil that prevents metal-to-metal contact between the crank journals and the rod and main bearings another very important design element of the crankshaft is the radius fillet Engineers take great care when designing this because a proper radius fillet is key to a crankshaft not breaking apart the radius fillet is key because it spreads the load and relieves the stress in what would otherwise be an extremely common stress fracture point in pretty much every gram shaft something that is machined at a perpendicular and sharp handle is much more prone to a stress fracture when compared to something that has a fillet instead of his sharp [Music] so now that we know what a crankshaft is and what it does and what are its parts we're going to find out about the forces acting on the crankshaft now the most obvious source of forces acting on the crankshaft of course come from the combustion generated by an internal combustion engine now modern spark ignition petrol engines that are naturally aspirated usually generate combustion pressures in the neighborhood of around 100 bar compression ignition engines and forced induction engines usually generate wise that around 200 bar of combustion pressures now a 100 bar combustion pressure acting on a 4-inch diameter piston which is around 10 centimeters is going to generate a force of around 18,000 pounds that around 8 tonnes and to put this into perspective the best and strongest boxers in the world their punches usually struggle to generate around 1000 pounds that means a naturally aspirated petrol engine generates forces that are 18 times stronger than the strongest punches in the world compression ignition engines such as Diesel's and forced induction engines generate 36,000 pounds of force that's 36 times more than the strongest punches in the world and the crankshaft being connected to the piston via the connecting rod is subject to these punches thousands of times per minutes as the engine reaches ever higher rpms think about that next time you're cruising down the highway but it gets even more dramatic most engines today are multi based on engines that means they have more than one piston per crankshaft and different Pistons are doing different things at different times in the engine one is accelerating the other is coming to a sudden stop so what they're trying to do to the crankshaft is basically they're trying to tear it apart all the time and surprisingly they almost never managed to tear the crankshaft apart and unless something goes horribly wrong elsewhere in the engine the crankshaft is almost never going to fail it's going to survive an infinite number of these extremely strong punches before it comes to the end of its lifespan and combustion pressure generated forces are just one part of the forces acting onto the crankshaft it also experiences primary and secondary shaking forces in primary and secondary rocking the moments and a bunch of other stuff so it really is going through hell all the time and this is why it's absolutely imperative that the design and the manufacturing process of a crankshaft is really good so that a crankshaft can survive all this hell for a very long time when it comes to the manufacturing of crankshafts there are three main manufacturing processes and they greatly determine the strength and performance potential of a crankshaft the three manufacturing processes are casting forging and CNC machining casting is by far the most cost effective process when it comes to manufacturing crankshafts the downside is that in general cast cranks are pretty weak they're very brittle brittle meaning that they have a low wall tensile strength and a world that early when compared to forged cranks or cranks machined out from a billet cast crank shafts are made by casting molten metal into a mold and letting it set this usually results in a pretty random grain structure grain structure is the distribution and orientation of metallic particles within a metal part and it greatly influences the strength of that metal part now a random grain structure usually results in a pretty weak and brittle part when it comes to the materials used cast pranks are most often made from nodular iron or steel and they have a typical tensile strength of around 60,000 to 100,000 psi and an elongation rating of around 2 to 3 percent now cast crank shafts used to be pretty common in car and motorcycle engines but nowadays you'll be hard-pressed to find a cast crank in a modern serious engine nowadays manufacturers usually rely on forging for the crank shafts and cast cranks are usually reserved for all Moors mopeds all displacement scooters and chainsaws the forging process involves a large crankshaft sized billet being heated up to around 2500 degrees Fahrenheit the healing up billet is then put in a giant press which has dyes in it the press then applies in ones from 150 to 250 tons of pressure to shape the billet into a rough forging the rough forging is then machined and heat treated to produce a finished crankshaft you can tell a crankshaft is forged by looking for signs of grinding on it now during the forging process excess material known as flash comes out of the forging dies this then needs to be round or plane leaving behind a telltale sign of a forged crankshaft the forging process itself significantly compresses the grain structure of the forged crankshaft it creates a much more uniform grain structure compared to it cast part and this means that forged crank shafts are typically not just stronger but significantly more ductile when compared to cast crank shafts now forged crank shafts can be made from a wide variety of materials om crank shots are usually made for boiling carbon steel usually the 1053 or the 1045 alloy now the tensile strength of these hours is usually around 110,000 psi and well this doesn't seem that much more when compared to a cast crankshaft it's the ductility of forged crankshaft that is much better when compared to cast once a step up in terms of forged crank alloys is 51:40 chromium steel and it's usually rated at around 150 thousand psi tensile strength beyond that we have ours with even greater chromium and carbon content such as 41 40 and these are often used for most high-performance forged crank shafts and they are rated at around 150 K psi top-of-the-line Racing Forge cranks usually features forty three forty hours and these even stronger and tougher and they're usually rated at around 140 K psi when it comes to build crank shafts there's no forging or casting you simply take a billet and you machine away until you're left with a crankshaft naturally this process takes a long time and a lot of material gets removed and this is like billet crank shafts are usually pretty expensive and often reserved for racing and other extreme applications the great thing about billet crank shafts is that you have infinite design possibilities you can make the trolls as long as you want you can make the journals as thick as you want to and the process is suitable for custom one-off crank shafts which isn't the case when it comes to forging or casting very large tooling investments are needed for forging and casting and these are justified only when the large-scale mass production takes place now during the forging process of a crank shaft the grain structure of the metal gets deformed reshaped and stretched at very high temperatures this leaves some residual stress in the metal now in contrast to this built crank shafts get to retain the grain structure of the metal and it remains unchanged without any residual stress now both forged and David kram shafts get machined but the machining is actually seen as well as disruptive in the case of the billet crank shafts and they get to retain an optimal grain structure another benefit of CNC machining is that it's very precise and it enables very very precise shaping and location of the cranked rolls now this enables higher strength and ease your bouncing later on in the process typically the crank shafts are made from the 43 40 hour or better and they usually have a tensile strength rating of around 160 thousand 265 thousand psi once a crankshaft has been machined it often undergoes heat or surface treatments the goal of these is to stabilize and more importantly harden the surface of the metal this makes it more impact wear and fatigue resistant and significant to increases the lifespan of the crankshaft now modern cast crank shafts typically don't undergo heat and surface treatments the manufacturing and subsequent machining process hardens the metal sufficiently so there's no need for additional treatments and this is good because it usually means that cast crank shafts can be Rhema Sheen or reground without any need for repeated heat or surface treatments on the other hand forged crank shafts usually start out by being Shafter then cast crank shafts and they do require heat or surface treatments most OEM crank shafts undergo something known as induction hardening this is a no-contact process that uses an alternating magnetic field to rapidly heat up the journal surface of the crank shaft thereby hardening it it's sort of similar to how an induction stovetop works well sort of but it's great because it's really well suited to mass production it's inexpensive and it's fast and while it's more than adequate for most OEM and even performance applications it does have a drawback in the sense that it doesn't heat up the entire surface of the crank evenly which leaves behind some uneven stress areas in the crank shaft and this is why extreme racing applications often rely on more advanced surface treatments such as tuft riding or nitronic tough driving immerses the crankshaft in hot cyanide compounds this creates a thin layer on the surface of the crank shaft this thin layer is very resistant to wear and fatigue and however there is a grower back because stuck driving introduces a bit of warping to the crank shaft and this must be addressed after the tough driving process is completed now night riding is the more common process when it comes to surface treatments and it involves the crank being heated up in any special furnace and then exposed to nitrogen and ammonia gases these react with the carbon on the surface of the crankshaft thereby making it much harder nitriding doesn't penetrate as deep as stuff writing but it does have advantage in the sense that it doesn't introduce any warping to the crankshaft annoying conduction hardening both tough driving and night driving hardened entire surface of the crankshaft evenly so there aren't any uneven stresses left behind and this makes these processes more suitable to the forces seen in extreme racing applications however it must be noted that any surface or heat treatment done to the crankshaft will be compromised when a crankshaft is reground and in order for the initial wear resistance and hardness to be restored a heat and surface treatment must be repeated after machine as you're probably aware engine oil is the lifeblood of any internal combustion engine without enough oil and enough oil pressure almost any engine is going to fail pretty quickly and this is why great attention is given to the design of the oil delivery system within a crankshaft a typical om crankshaft is going to be cross drilled and this means that the main journals and often the rod journals will have to oil delivery holes in them the journals are in effect cross drilled and this is followed up by a drilling and an angle from the rod journal to the main journal to create a path for the oil between these two journals the drilling is then capped off like this oil holes on both the main journals and the rod journals are pretty much always chamfered if you ever see a non channel for the oil hole on a crankshaft which is very rare even in cheap reproductions walk away an alternative to the cross drilled design is a straight shot oiling design when it comes to straight shot oiling you won't find two holes on the main and rod journals of these cranks but rather only one oil delivery hole a journal and then you're going to see a straight and interrupted doing between these two holes of the main and rod journals and because of this there's also no need to cap anything off now straight shot oil ink is since a superior crankshaft application according to Sun and this is because in a cross drilled crankshaft pressurized oil must enter the main journal and overcome the centrifugal force of rapid acceleration or rpm to reach the center of the crank before the oil can travel to the drone I eat them broad journal now increased oil pressure is often used to overcome this centrifugal force but in extreme applications enough pressure sometimes can that be generated and this can result in engine failure and while this argument is a valid one and while in certain applications a straight shot oiling system may be superior it's naive to issue bar and get statements that all cross drilled cranks are simply obsolete and that they shouldn't be used I mean the design has been around for decades and countless racing teams at the highest levels of motorsport have achieved countless victories with cross drilled cranks in their cars so they really can't be simply eliminated by buying good statements remember those crazy forces that we mentioned in the beginning of the video that the crankshaft is exposed to well the counterweights have the very important task of balancing out these forces counterweights balance out the masses of the pistons and con rods and the piston rings and the piston pin and their associated forces counterweights ensure that there is no vibration and that an engine runs smoothly for a very long time and this is right often when a crankshaft is described you're going to hear the term for e counterweighted a fully counterweighted crank oops alright this if fully counterweighted crankshaft is going to have to counter its opposed to each rod journal and inner and four crankshaft that isn't fully cultivated it's gonna look sort of like this if fully counter where your crank is often seen as a superior crankshaft to a partially cultivated one it ensures a smoother running engine and a better ability to cope with extended high rpm operation engines that come with high red lines from the factory almost always have fully counter rated cracks something else you're often going to see your graham chef's counter weights are holes like these these are created during the manufacturing process at the factory when a crankshaft is spun at high rpm on a special machine which dynamically balances the crankshaft it identifies points on the contour it's where weight needs to be removed in order to ensure a perfectly balanced crash another important thing when it comes to performance engines and crankshaft is the shape of the counter it's themselves and it needs to be as aerodynamic as possible to combat winding in the crankcase of an engine why that is the turbulent flow of oil infused air within the crankcase that creates a significant drag on the rotational motion of the crankshaft a more aerodynamic shape of the counterweights is going to ensure less drag and this is why you will sometimes see crank shafts intended for performance being in knife 8/9 edging means creating this sort of sharp knife wide shape on the counterweights the goal of the shape is of course to reduce the drag on the other hand build crank shafts are often going to have these sort of aerodynamic shapes already incorporated in their counterweight design now racing crank shafts aim to be as light as possible and this is because a lighter engine internals mean a more red happy engine any better throttle response and this is why you will sometimes see racing brand shots having grilled crank vents or a reduced number of counterweights now the comparison between flat point and crossplane crankshaft deserves an entire video on its own so here we're going to just briefly summarize the two types and all get the pros and cons of each type now flatpoint crank shafts as the name suggests they're in a single flat plane the rod journals are offset 180 degrees from each other which means that both the main journals and all the rod journals are in a single point hence the name flat point on the other hand a crossplane crankshaft has the rod journals offset 90 degrees from each other which results in the rod journals being in two different planes and these points are perpendicular to each other because the journals are offset 90 degrees and hence the name cross point the two points are crossing each panel now when it comes to annoying four engines almost all inline-four engines feature a flat plane crank shaft crossplane crankshaft are extremely rare when it comes to inline four engines on the other hand v8 engines feature both fine point and crossplane crankshaft the traditional muscle car v8 almost always features a crossplane crankshaft and crossplane crankshaft means that there's a cylinder firing more often when compared to a flat plane crank shaft and this is good because it creates a smooth running and they better balance between the different between the two banks of the v8 engine but typically crossplane crankshaft are bulkier and heavier when compared to fire points and this makes the MOA suited for high rpm operation on the other hand flat plane crank shafts are better inherently balanced and they're capable of much higher max RPMs they also sound very different fourth point crack shots also more compact by design so you can make the engine smaller a grasp point crankshaft is typically going to require a larger crank case on the other hand the flat point does have its disadvantages and typically it's going to be more prone to vibration when compared to a cross plane it's also typically going to make ice and there you have it those are pretty much the basics when it comes to crankshaft I hope you enjoy this video and I hope you found it useful also thanks for watching and I'll be seeing you soon with more content on the day for a engine boot camp

Channel: driving 4 answers

Views: 272,952

Keywords: how crankshaft works, types of crankshaft, crankshaft parts, crankshaft function, crankshaft mechanism, crankshaft material, crankshaft motorcycle, crankshaft manufacturing process, how it's made crankshaft, crossplane vs flat plane, forged crankshaft, billet crankshaft, billet crankshaft vs forged, induction hardening, nitriding crankshaft, knife edged crankshaft, crankshaft machining, crankshaft, engineering explained, v8 crankshaft, crankshaft balancing, cross drilled

Id: hN24AL5fDgQ

Length: 27min 47sec (1667 seconds)

Published: Sun Mar 29 2020