Cast Crank VS Forged Crank

Sound the difference

Category:

Education

Tags:

• Cast
• Crank
• Forged

[itdontgo]

You dont think something that is loaded by a piston doing 0 to 100mph and back to 0 again every half a cycle (not to mention the work load) can take a tap with the hammer?

[fopeano]

@golbis The two crankshafts are the same dimension/size. the cast one makes a lower pitched sound because the grain structure is more relaxed and there fore complies with applied forced more. The forged crank sounds higher pitched because the grain stucture is tighter and stiffer, causing the same effect as say a guitar string that plays a higher pitch when tightened, and also deflects less against a specific amount of force than if it was looser.

[trancepose]

@murphystreeter because of the manufacturing costs. Cast steel cranks perform more than enough in most of the family cars etc. Forged cams are usually used in mass produced performance vehicles (not sure about trucks and other applications)

[murphystreeter]

I guess they do make cast steel cranks but I prefer to use a forged as they are stronger. Hypereutectic pistons are junk, they just don't hold up like the forged pistons. Mahle pistons are the best but forged work very well. Sorry, I'm rambling, but this video I believe shows a cast iron crank on top and a steel crank on bottom but I can't tell if it's forged or cast.

[murphystreeter]

The one on top is cast iron...there is a difference. Iron vs. steel (alloy) Iron is not alloy, it's just nodular iron and cast into shape. The steel is much stronger. Nodular iron is soft and will wear over time. (400 ford is the perfect example) The forged crank is much stronger and has a higher pitch. As for rings, cast rings are the best on the market today. Chrome rings lose their tension when they get hot. I must ask, though, do they make a cast steel crank?

[784plb]

its not grain structure, its carbon magonese density in forged producted. its basic physics, has nothing to to with how much grain the metal has. its the chemical process that changes everything. the carbon, magonese combine and joined and in larger molecule groups resulting in a forged product.

[2jzgtejza80]

@jcadlols

Forging and casting are two totally different types of shaping metals.

[2jzgtejza80]

@1magnit

Steel is very hard to cast specially steel alloy for crankshafts, no one do that anymore. There's 3 basic types of making cranks;

1. Cast in sand mold (Ductile Iron, or better Austepered Ductile Iron-known as ADI)

2. Forged with high force press (1500-2500 tons) in metal mold made from Hatfield Steel 12% manganese.

3. Cast in billet, heated, forged billet, and than machined in CNC = (most expensive and the most precise proces)

[cronos51101]

To some extent, the forged crank is cast, but while the cast crank is simply cast and ground, the forged crank is cast in a continuous process which usually involves metal with far superior chemical properties. After that, the metal is hot worked which improves its mechanical strength, and cold worked into the crank shape. The cold work creates a significant increase in mechanical strength due to the effect it has on the (already superior) grain structure and grain boundaries. Then it's ground.

[4mulas]

Cast = shape by sand molding

Forging = shape by press forces

[jcadlols]

@1magnit A forging is a casting, it is just heat treated and often a better alloy than cast iron.

[1magnit]

They're both cast.

One is cast iron, the other cast steel