What's the difference between "forged" and "extruded?"

J

Jack 99

New member
Reason I ask is mil-spec for the M16/AR15 charging handle assembly is apparently from an extrusion. Bushmaster sells forged charging handle assemblies and also claims they are mil-spec. Its either one or the other.

I know, these are probably nit-picky differences, but I live for this stuff.
 
Extruded, as you probably know, is where metal, aluminum, magnesium, etc, is forced into a chamber, and through a "hole" of a specific shape, or form. It's how channeled aluminum is typically made. Usually an extrusion will be more uniform in dimension than a forging.

A forging OTOH, is a piece of metal that is hammered into a specific shape in a mold with that shape.

The forgings are generally stronger than extrusions, for the same given metal. I'm not a metallurgist, so I don't know the exacts of this, but it has to do with the crystallines structures of the surface of the item being forged.
Forging uses the same surface area as when produced from the foundry, thereby you retain this inherent surface characteristic after the piece is forged.

Extrusion destroys the "surface properties" in the process of forcing the metal through the form to achieve the desired shape.

As for mil-spec of the charging handles...

A forging will yield greater strength, and still be within tolerance specs for part dimensions.
An extrusion, as I mentioned will inherently be closer to the desired dimensional right out of the process, without further finishing required (read=cheaper to make). And it can still be strong enough to satisfy mil-spec for tensile strength, providing proper alloy is used.


Best Regards,
Don

------------------
The most foolish mistake we could make would be to allow the subjected people to carry arms; history shows that all conquerers who have allowed their subjected people to carry arms have prepared their own fall.
Adolf Hitler

[This message has been edited by Donny (edited May 22, 2000).]
 
I wonder which one is *really* Mil-Spec?

It depends on how the spec is written. If they are performance specs, i.e. "...said piece will have have x tolerance and x strength..." then its possible they both could meet spec.
 
Good answer, Phil!

May I expand? If it is a "build to ..." spec, it will (should) contain every dimension to be met, usually verified by inspection (including measurement). If it is a "performance" spec it will require certain performance requirements to be met after production, usually verified by testing.

Therefore, two contractors could meet a "build to ..." spec, but only one, or neither, or both, could meet the performance spec. On the other hand, if you meet the performance specification, you have met all elementary dimensions and probably have, by default, met any and all relevant "build to ..." specifications.

"Build to ..." specs are great for ash trays and pencils. For more complex items that require a minimum level of performance, but don't have a requirement for, say, color, or perhaps weight, a performance spec is better, because if you release a specification that requires a complex item to be built exactly a certain way ("build to ..."), then you'd better be right about every aspect of the specification. Otherwise you'll find yourself mumbling that same utterance heard by US Government contractors through the ages ..."Oh, $H!T! You built it just like I told you!"

<BLOCKQUOTE><font size="1" face="Verdana, Arial">quote:</font><HR>I wonder which one is *really* Mil-Spec?[/quote] Probably both. This is a really simple item to spec. Different methods can achieve the same result, in this case.



[This message has been edited by sensop (edited May 22, 2000).]
 
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