Speaking of forged axles, I saw this one at the LARS swap meet. Allegedly, this is one of several Ford used to demonstrate the strength during a World's Fair exhibit. It was supposedly bent cold, on site. Anyone know something about these?
Malleable iron is often used today where cast or forged steel would have been used in the past. All things being equal, ordinary mild(low carbon) steel is tougher(more fatigue resistant) than the malleable iron. And, a properly made forging is tougher than a casting made of the same material. But, a forging that isn't made properly can be weaker and more fatigue prone than a good casting. I spent several years working for an OEM component testing lab. Everything has a fatigue limits. How a part is used, and how much it is used, determine how long before the part breaks. Think of it in terms of making gravel from rocks, lots of hits with a small hammer or a few hits from a big hammer both produce pretty much the same result. Manufacturers normally include a lot of safety margin in safety-critical parts like steering knuckles, wheel hubs, steering arms, spindle stems, etc. So, when a part like that breaks in normal use it's an indication something went seriously wrong.
Something looks strange here. I would think that an axle twisted like this (especially cold) would be a lot shorter than this one appears to be. Wasn't there; don't know.
I know it's awesome. And if you see some R R's show up with that look, you'll know where they got the idea from. Anyhow, this subject is so beat to death it's useless were it not for the twisted axle pic..
On the rod in question I am sure it was just a bad part. It separated on the small end as opposed to the big end where they normally separate from being overstressed in a performance engine. After that we started magnafluxing all the rods for that particular project and found several out of a couple dozen with a fracture line near the small end. Maybe there was a bad batch. My point is that being forged does not mean that it will not break.
My guess is that whatever hooked to the ends of the axle were set at a fixed distance from each other, thereby stretching the axle at the same time it was twisted, otherwise it would have curled up like a pig's tail...
A number of years ago I remember a run of defective Pontiac 421 Super Duty rod forgings. I ran across a large size, high-dollar, high pressure hydraulic fitting that had a deep imperfection where the the metal folded during forging. There have been crankshafts that were not forged properly and tended to fail.
Exactly, given my options I will almost always choose a forged part over a cast part. But I would not go so far as to say that just because it is a forging it is bullet proof. One thing about a forging that I have noticed is that more often not that flaws in a forging are more noticable than flaws in a casting. Like your hydraulic fitting for instance. I bought a 55 gallon drum full of forged harley head bolt wrenches once. They were cheap as dirt and for good reason, there ere only about 100 of them that were good wrenches. The rest had places in them that looked wrinkled and when you applied pressure to them that would break. They ended up costing about the same as retail. Oh on another note I have seen that pic of the twisted axles a bunch of time. I would have liked to have been there to watch then getting twisted that must have been one helluva machine.
Ford did those at the World's Fair; cold, IIRC. Too bad the aftermarket axle people don't try the same thing.
How did they forge the axle in the shape of an axle versus casting the axle? Do they just pressurize the casting and that makes it forged?
Here are the basics for this type of forging: They use raw steel forging blanks, heat the blanks up to a desired temperature, have huge presses and ***ociated forging dies - and beat the **** out of it to 'form it' to shape. The metal oozes out of the sides at the die 'parting line' areas, is trimmed off, etc.. That is why you see a 'parting line' on most forged parts. There are obviously many nuances and more advanced techniques today (like powdered metal forging) - but the above should get you started!
That's what Auto makers do nowadays. They only think in parts per million (PPM), and then come up with a number that's acceptable.
the 'superbell' logo on the axle is kool! id gladly run one! WAIT..... i have been running one and several SEVERAL other people are also running them and have been for a lot of years. anyone have a chrome cast axle they are afraid to use i may be interested in buying it.
Much of the testing and development done on cars is not intended to make them more durable. Rather, it is done to make the car lighter/cheaper/better, without sacrificing too much safety and/or durability. Safer and more durable cars can be made. People are only willing or able to pay for so much of that. Car manufacturers have performance and durability "bogies" for pretty much everything. Some are government requirements and standard industry practices, most are self-imposed. Factors like performance, weight, economy, and cost, are often at opposite extremes from maximum safety or durability. Finding the best compromise is not the manufacturer cheating the customer. That happens when the manufacturer intentionally or accidentally makes a bad compromise.
You guys are right on message. Here's what I posted on my site in NZ after we had seen some broken axles: http://lowvolumevehicle.co.nz/metallurgy/ Metallurgy Metallurgy Since the birth of the motor car, front axle beams have been made from Forged Steel. Steel is Iron that has had the Carbon content reduced to about 0.5%, and Forging is a hammering process which creates a grain structure aligned with the forces in the component. A Forged steel component is “TOUGH” and “DUCTILE” which means it will bend but not break easily. Cast iron is the poorest grade of Iron used, and has about 5% of included Carbon. The Carbon lies around in pretty flakes, along with perlite and magne***e, which are Carbon Iron alloys. Cast Iron is weak, and brittle, not suitable for safety related applications. During the Industrial revolution, many disasters resulted from failure of Cast Iron components. In the years before Steel making was practiced on an industrial scale, the material of choice was ‘Wrought Iron’ in which the Iron is beaten out into long shapes, so that the 5% Carbon is stretched out into long streaks, interspersed with streaks of clear Iron. Look up ‘Iron Age Man’ to see how these technologies were evolved thousands of years ago, to make better swords and ploughshares. Steel results from a smelting process, such as the Bessemer Converter, in which most of the excess carbon is burnt out by blasting Oxygen through the melt, leaving a material with around 0.5% carbon. This makes possible the manufacture of a wide range of steels with consistent high strengths Steel is usually supplied in rolled products, and can truly be called the material on which our modern civilization is built. Steel can also be cast, to create a relatively high strength products with toughness and ductility, many cast steel components are used in motor vehicles. The ultimate material is of forged steel, which has a grain structure aligned to the stress paths in the component, which is why vehicle beam axles are invariably made from forged steel. SG or Nodular Cast Iron An improved grade of cast Iron was introduced in the late 1950’s termed “Spheroidal graphite” Iron, or “Nodular Iron”. In this material, the Carbon, perlite and magne***e remain, but the free carbon is made to form round blobs. This greatly increases the strength and even creates some ductility compared to “Grey” or “Flake” cast Iron. The most common use of this material is for Sewer Pipes, Drain covers. In motor vehicles use is usually confined to Engine blocks and Gearbox cases, although it has been used for crankshafts for compressors and low powered, low cost engines. There is not just one type of SG or Nodular iron, and the manufacturing process can create a wide range of properties and characteristics The metallurgy of SG Iron is tricky, and careful Quality control is always required. Just examining the material with a microscope, in one spot, may offer some clues about the structure AT THAT SPOT, to an experienced Metallurgist or NDT technician. Doing what LVVTA have done- promoting a motor mechanic to a metallurgist by hiring him a microscope is a case of a little knowlege being a dangerous thing. Here are some information on automotive applications for SG or Nodular Cast IRON Ductile Iron Society and Here is some information on Vanadium Steel, used for hot rolled sections and forgings http://vanitec.org/wp-content/uploads/2011/09/Vanadium-in-Medium-and-High-Carbon-Steels.pdf Written just out of my head, some research will produce far better sources on information on this huge topic John Brett
You guys are right on message. Here's what I posted on my site in NZ after we had seen some broken axles: http://lowvolumevehicle.co.nz/metallurgy/ Metallurgy Metallurgy Since the birth of the motor car, front axle beams have been made from Forged Steel. Steel is Iron that has had the Carbon content reduced to about 0.5%, and Forging is a hammering process which creates a grain structure aligned with the forces in the component. A Forged steel component is TOUGH and DUCTILE which means it will bend but not break easily. Cast iron is the poorest grade of Iron used, and has about 5% of included Carbon. The Carbon lies around in pretty flakes, along with perlite and magne***e, which are Carbon Iron alloys. Cast Iron is weak, and brittle, not suitable for safety related applications. During the Industrial revolution, many disasters resulted from failure of Cast Iron components. In the years before Steel making was practiced on an industrial scale, the material of choice was Wrought Iron in which the Iron is beaten out into long shapes, so that the 5% Carbon is stretched out into long streaks, interspersed with streaks of clear Iron. Look up Iron Age Man to see how these technologies were evolved thousands of years ago, to make better swords and ploughshares. Steel results from a smelting process, such as the Bessemer Converter, in which most of the excess carbon is burnt out by blasting Oxygen through the melt, leaving a material with around 0.5% carbon. This makes possible the manufacture of a wide range of steels with consistent high strengths Steel is usually supplied in rolled products, and can truly be called the material on which our modern civilization is built. Steel can also be cast, to create a relatively high strength products with toughness and ductility, many cast steel components are used in motor vehicles. The ultimate material is of forged steel, which has a grain structure aligned to the stress paths in the component, which is why vehicle beam axles are invariably made from forged steel. SG or Nodular Cast Iron An improved grade of cast Iron was introduced in the late 1950s termed Spheroidal graphite Iron, or Nodular Iron. In this material, the Carbon, perlite and magne***e remain, but the free carbon is made to form round blobs. This greatly increases the strength and even creates some ductility compared to Grey or Flake cast Iron. The most common use of this material is for Sewer Pipes, Drain covers. In motor vehicles use is usually confined to Engine blocks and Gearbox cases, although it has been used for crankshafts for compressors and low powered, low cost engines. There is not just one type of SG or Nodular iron, and the manufacturing process can create a wide range of properties and characteristics The metallurgy of SG Iron is tricky, and careful Quality control is always required. Just examining the material with a microscope, in one spot, may offer some clues about the structure AT THAT SPOT, to an experienced Metallurgist or NDT technician. Doing what LVVTA have done- promoting a motor mechanic to a metallurgist by hiring him a microscope is a case of a little knowlege being a dangerous thing. Here are some information on automotive applications for SG or Nodular Cast IRON Ductile Iron Society and Here is some information on Vanadium Steel, used for hot rolled sections and forgings http://vanitec.org/wp-content/uploads/2011/09/Vanadium-in-Medium-and-High-Carbon-Steels.pdf Written just out of my head, some research will produce far better sources on information on this huge topic John Brett
I think that magnum has a bad run of axles but they have no way of determining if your axle is part of that run. I have looked at several of the broken axle threads and they all seem to have the same broken axle so while there is a lot of talk of broken cast axles there only seems to be one that any hambers can come up with a picture of. to me that makes it talk and just talk. That said, I would prefer to run a forged axle. But either way if it is a dropped axle it is probably a good idea to maganaflux or die test it. Obviously maganafluxing is your best bet but a die test will do in a pinch.
I feel that forged is the only choice in something as important as a front axle I have worked with allot of cast iron and there is nothing that can convince me that a cast iron axle should be under vehicle one person getting killed or seriously injured from an inferior axle is to many
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