Con Rod Forging Die Tolerance 1

[Conrodman]

We have tried to search the "Forging Industry Association" site with little sucess.
Can anyone help us with the tolerance typically allowed for forging die mismatch for a connecting rod?
The rod is ~7.00" ctr/ctr (Pin End Bore to Journal End Bore) and forged from 4340 alloy.
Also how is it measured?
Thanks

 

[Fabrico]

I would shoot for .010" or less just for cosmetic value alone. Not sure how it is tyically measured, but it sure shows up when the part line is ground off.

 

[mattsooty]

With shot peening?

MS

 

[Fabrico]

OK, maybe .012" to .015". But you can peen it with shot, beat it with a ball peen hammer, or even a sledge, and still easily see die alignment and ground areas.

 

[Conrodman]

The Forging sources we have dealt with indicated from .015 to .030 and differed greatly as to how and where to measure.
Mismatch is a very cosmetic as well as machining nightmare. When machining it is difficult to "average" the mismatch to avoid what appears to be a error in machining when a thru hole is compared from one side of the rod to the other.
Forge suppliers also differ in their ability to define and measure mismatch. Also, we have been told that the mismatch allowance is in addition to all the dimensional tolerances.
Thank you all for your comments.