What's the difference?
mena661
Billet starts off with a large block of aluminum and is machined. They remove a large amount of material to get the finished product. One wheel might start off with a 250 lb block of aluminum.
Forged starts off with molten metal that is poured into a mold to arrive at a nearly finished product. This forged end product is then sometimes machined to the final specs. Very little material is removed, just enough to give it a good finish.
REVISED INFORMATION: Forged starts off with usually hot metal either pounded or pressed into a specific shape.
CAST starts off with molten metal.
Forged starts off with molten metal that is poured into a mold to arrive at a nearly finished product. This forged end product is then sometimes machined to the final specs. Very little material is removed, just enough to give it a good finish.
REVISED INFORMATION: Forged starts off with usually hot metal either pounded or pressed into a specific shape.
CAST starts off with molten metal.
^^^
edit: you beat me to it.
I can only give a very brief overview because I don't know the full processes.
That said, a billet is simply a slab of steel. It is really a designate of size and shape for easy logistical movement. I work for a railroad and we move billets. So when you purchase something that is billet steel - I believe this simply means it is all cut from one piece. It sounds fancier than it really is. The quality of the billet is more important. You can have weak and crappy billet AL, or very high grade aircraft AL in billets.
Forging, is performed in hot or cold processes, mostly hot. This takes again a solid one piece of metal, but it is forced at extreme temps and high pressures into a mold, hence making it stronger and in some cases "fatiguing" the metal to make its final structure resistant to cracks as it returns to normal temperatures.
Someone correct me if I'm wrong here...
edit: you beat me to it.
I can only give a very brief overview because I don't know the full processes.
That said, a billet is simply a slab of steel. It is really a designate of size and shape for easy logistical movement. I work for a railroad and we move billets. So when you purchase something that is billet steel - I believe this simply means it is all cut from one piece. It sounds fancier than it really is. The quality of the billet is more important. You can have weak and crappy billet AL, or very high grade aircraft AL in billets.
Forging, is performed in hot or cold processes, mostly hot. This takes again a solid one piece of metal, but it is forced at extreme temps and high pressures into a mold, hence making it stronger and in some cases "fatiguing" the metal to make its final structure resistant to cracks as it returns to normal temperatures.
Someone correct me if I'm wrong here...
Billet anything is usually stronger than cast. Not sure if your talking wheels or engine parts but another important consideration is cost$$$$ The price is going to be much higher when looking at Billet material, I think it's worth it....
"Billet starts off with a large block of aluminum and is machined"
...and basically the large block of aluminum was forged at some point in the manufacturing process.
Forging is :
1.To form (metal, for example) by heating in a forge and beating or hammering into shape.
2.To form (metal) by a mechanical or hydraulic press.
What are you trying to buy that is comparing billets and forgings?
...and basically the large block of aluminum was forged at some point in the manufacturing process.
Forging is :
1.To form (metal, for example) by heating in a forge and beating or hammering into shape.
2.To form (metal) by a mechanical or hydraulic press.
What are you trying to buy that is comparing billets and forgings?
I always see these terms used to describe stronger aftermarket parts like rods, cranks, and pistons. Domestic car guys use "billet" to describe stronger parts and everyone else uses "forged" or "billet". I wanted to know the difference and if one process is stronger than the other.
Forged parts are stronger than machined, but I had always thought that the terms billet and forged were essentially interchangeable. They are when it comes to wheels anyway. You could really do either process with a billet. You could machine it or you could put it in a forge and whomp it into shape. For that matter, you could melt it down and cast it. :lol:
For more information on forging, see http://en.wikipedia.org/wiki/Forging
For more information on forging, see http://en.wikipedia.org/wiki/Forging
One generally does not forge soft metals like aluminum; forging steel and bronze, however, adds strength, especially cold forging. Quality wrenches, for example, are cold forged.
Billet aluminum parts are usually better than cast, because a properly poured billet has uniform internal structure, which improves stress tolerance. Parts that are cast to shape will have more varied structure, especially where the metal has to flow around corners to fill the mold, unless the part is pressure cast (like Honda motorcycle engines). Pressure casting produces a finer, more uniform internal structure in a soft metal, that gives enhanced strength the way forging does for harder metals. It used to be that pressure casting small parts was cheaper than hogging the same part out of a large block; modern high-speed milling machines have changed the cost ratio.
Billet aluminum parts are usually better than cast, because a properly poured billet has uniform internal structure, which improves stress tolerance. Parts that are cast to shape will have more varied structure, especially where the metal has to flow around corners to fill the mold, unless the part is pressure cast (like Honda motorcycle engines). Pressure casting produces a finer, more uniform internal structure in a soft metal, that gives enhanced strength the way forging does for harder metals. It used to be that pressure casting small parts was cheaper than hogging the same part out of a large block; modern high-speed milling machines have changed the cost ratio.
well, almost
Billet is distinctly different from forged.
A billet is generally a rolled/ shaped slab (which at some point was poured into an ingot mold). This process causes the grain of the metal to align, thus giving strenght against a force (bending, shear, etc.). These pieces are usually limited to long aspect parts that are subjected to stress along one plane.
A forged piece as stated earlier is an item that has been cast into a more intricate shape (ex. crankshaft) and then "hammered." The cast piece is oversized and has a random grain structure. When the pounding force is applied, this causes the grain of the metal to "fit" together better to form a more integral flow of interlocking molecules which gives it an increased breaking strength.
Imagine taking hamburger meat (cast but not forged), shape it into a patty and a slab of wood cut to look like a hamburger patty. The meat patty one will come apart in any direction and the wood one is very strong one way versus the other. If the meat patty is massaged, kneaded, compressed (forged) into a patty shape, it will resist tearing, breaking, and crumbling in more directions of stress than the other processes.
So, depending on what kind of part you are looking at purchasing, forged vs. billet could very well be important to its effectiveness.
Billet is distinctly different from forged.
A billet is generally a rolled/ shaped slab (which at some point was poured into an ingot mold). This process causes the grain of the metal to align, thus giving strenght against a force (bending, shear, etc.). These pieces are usually limited to long aspect parts that are subjected to stress along one plane.
A forged piece as stated earlier is an item that has been cast into a more intricate shape (ex. crankshaft) and then "hammered." The cast piece is oversized and has a random grain structure. When the pounding force is applied, this causes the grain of the metal to "fit" together better to form a more integral flow of interlocking molecules which gives it an increased breaking strength.
Imagine taking hamburger meat (cast but not forged), shape it into a patty and a slab of wood cut to look like a hamburger patty. The meat patty one will come apart in any direction and the wood one is very strong one way versus the other. If the meat patty is massaged, kneaded, compressed (forged) into a patty shape, it will resist tearing, breaking, and crumbling in more directions of stress than the other processes.
So, depending on what kind of part you are looking at purchasing, forged vs. billet could very well be important to its effectiveness.
Most of the information above is correct. Some clarification:
Casting: Molten metal is poured into a mold, and has grain structure that is more related to flow and cooling that final part use. It is cheap and easy to manufacture in large quantities, and in many applications works perfectly fine. There is typically a number of post-casting processing such as grinding, polishing, or machining. Cast metal can be prone to porosity, making them potentially brittle and/or weak. There are also different kinds of castings, e.g. sand (least expensive tooling), investment casting (more expensive tooling but better detail on final parts), and die casting (most expensive tooling), the latter typically used in soft metal applications.
Billet: Starts in ingot form (like al metals) as a big cast bar that is hot or cold rolled into plates or bars. The grain structure is aligned along the length of the bar, so aligning the grain to the final application before machining optimizes the strength of the part. This is the most expensive way to mfr parts as there is typically lots of waste. Porosity is not normally a problem with billet.
Forging: Forged parts begin with round bar stock heated to red hot soft, like very firm putty. The long bar is placed in a forging die (two part mold) and is hammered once or twice into the mold. The grain structure is nicely alignined (usually) with the final part, making it the strongest of the three mfg methods. Usually forged parts are then partially or fully machined (like a billet part), but at lower cost since the raw forging is close to final part shape.
There are other techniques that each method can use to further optimize function, strength, appearance, etc., but this gives the basic ideas of each.
Casting: Molten metal is poured into a mold, and has grain structure that is more related to flow and cooling that final part use. It is cheap and easy to manufacture in large quantities, and in many applications works perfectly fine. There is typically a number of post-casting processing such as grinding, polishing, or machining. Cast metal can be prone to porosity, making them potentially brittle and/or weak. There are also different kinds of castings, e.g. sand (least expensive tooling), investment casting (more expensive tooling but better detail on final parts), and die casting (most expensive tooling), the latter typically used in soft metal applications.
Billet: Starts in ingot form (like al metals) as a big cast bar that is hot or cold rolled into plates or bars. The grain structure is aligned along the length of the bar, so aligning the grain to the final application before machining optimizes the strength of the part. This is the most expensive way to mfr parts as there is typically lots of waste. Porosity is not normally a problem with billet.
Forging: Forged parts begin with round bar stock heated to red hot soft, like very firm putty. The long bar is placed in a forging die (two part mold) and is hammered once or twice into the mold. The grain structure is nicely alignined (usually) with the final part, making it the strongest of the three mfg methods. Usually forged parts are then partially or fully machined (like a billet part), but at lower cost since the raw forging is close to final part shape.
There are other techniques that each method can use to further optimize function, strength, appearance, etc., but this gives the basic ideas of each.
When it comes to high performance crankshafts, if you can get forged you do, if you need a custom configuation/size sometimes a forged piece isnt avialable and then if you go billet. Keep in mind that billet also gives you more flexibility in what alloys you can use.
On a side note, there are 2 types of forged cranks for "V" type engines, twisted and non-twisted. In a twisted type all the rod journals are forged in the same plane and in a post-forging process some of the rod journals are "twisted" to thier desired locations(60, 90, 120, etc. degrees off-set). In a non-twisted type all the rod journals are forged into thier final locations during the intial forging process. Non-twisted are stronger but the complexity of the forging dies make them more expensive.
On a side note, there are 2 types of forged cranks for "V" type engines, twisted and non-twisted. In a twisted type all the rod journals are forged in the same plane and in a post-forging process some of the rod journals are "twisted" to thier desired locations(60, 90, 120, etc. degrees off-set). In a non-twisted type all the rod journals are forged into thier final locations during the intial forging process. Non-twisted are stronger but the complexity of the forging dies make them more expensive.
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