Cast Crankshafts

[allanallen 528 2 Cars]

Bit of a confusing subject this one.... Right I'm fully aware of the difference between forging and castings, I work with both daily and as I write this I can actually hear a 10000 ton forging press bashing out jet engine parts!

 

 

What's a cast crank really? Can anyone show me a mass produced crank coming out of a casting?

I've googled it to death and seen lots of pictures of comparisons between finished forged and (what's called) cast cranks.

Is it all a big conspiracy and all cranks are forged? Enlighten me please

 

 

I'm not interested in billet cranks or billet rods that people think are forged either....

[allanallen 528 2 Cars]

I've had an argument over lunch about this if you haven't guessed I am under the impression that most mass produced cranks are cast

Edited October 16, 2014 by allanallen

[Tom Fenton 1,542]

I think all are forged. When back at work tomorrow I will enquire with the metallurgy goons upstairs.

[petert 587]

I found Youtube clips of each in <2mins. Nodular cast iron has to be poured and the steels start off as a billet, which has to be pressed into its general shape before machining.

 

The word billet meaning steel section 100x100mm or greater.

 

 

Edited October 20, 2014 by petert

[allanallen 528 2 Cars]

I don't follow, That's forging?!

Are you saying they're forged out of cast iron??

 

As I mentioned in my first post, I know what forging, casting and billets are. I'm more after understanding if cranks are actually cast.

Edited October 20, 2014 by allanallen

[petert 587]

The first video is forging, where a billet of steel is pressed between dies into the desired shape. The second, although an animation, shows liquid cast iron being poured into a sand mould. A cast crank is easily identifiable, as it has a thin parting line where the two halves of the mould meet. Cast cranks can also have letters/numbers raised on the surface. You could never do that with a forged crank. If you lay a forged XU diesel crank along side a cast XU crank, you can easily see the difference and appreciate the differences in the manufacturing processes.

 

Don't confuse the above two production processes with a"billet 4340 crank", which is cut by machine(s) from a billet of steel.

[JeffR 51]

The forging factory looks a nice, safe place to work! What is the guy throwing handfuls of into the press?

[allanallen 528 2 Cars]

The forging factory looks a nice, safe place to work! What is the guy throwing handfuls of into the press?

You wouldn't believe the amount of health and safety involved with forging!!

They throw all sorts in between whacking, sawdust is one of the main things afaik.

 

Petert, As I've said already said I know all the processes well, I've worked in foundries and I currently work with one of the biggest forging companies around.

 

I'm under the impression that cheap cranks are cast, I just want some evidence of it and can't understand why there isn't any if it's so common?

 

Forgings have split lines like castings do, where the two dies come together and push out the excess material

[allanallen 528 2 Cars]

Please don't confuse this thread with billet cranks, different topic Altogether and of no interest.

[petert 587]

haha, that's a bit hard when a forged crank is made from a billet of steel.

[calvinhorse 870]

The one in your video isn't? It's forged to the rough shape and then it will have only the bearing surfaces machined by the looks of it so it would show the flash marks

[allanallen 528 2 Cars]

 

Don't confuse the above two production processes with a"billet 4340 crank", which is cut by machine(s) from a billet of steel.

Why so condescending and pedantic?

 

I was referring to the above comment, I'm sure you're aware of that though. Maybe you should read my opening post again if you want to keep replying.

[petert 587]

Nope, I've got idea. I give up.