Aluminium forgings

I'm working on a design at present and looking at established
comparisons the main part will need to be an aluminium forging. I have
good experience with castings and machining from solid but experience
with forging is limited. I have never done it but understand the
process.

Has anyone here got experenece of costs, problem areas to avoid, and
maybe even uk based manufacturers?

All feedback appreciated.

 

Why does the main part need to be a forging?

 

It's a lightweight yet quite highly stressed part subject to pretty
severe shock abuse. It's not an aircraft application but the
environment is similar. If I can be connvinced that a cast part would
do then that would suit me as apart from production I do have to rapid
prototype the part.

 

In the aerospace industry modern machining methods have made forgings in
aluminum obsolete, plus the cost of tooling makes forgings a very expensive
process for all but high production runs. Use a 7000 series aluminum and
machine it.

 

Why not cast it and HIP it? Is the part going to be routinely inspected?

 

Really don't want to sound ignorant here (of all places) but what is
HIP?

 

Really don't want to sound ignorant here (of all places) but what is
HIP?

 

Hot Isostatic Pressing

 

not sure which part of the aerospace industry you,ve been exposed to
phil im pretty sure in the aerospace industry im involved in forgings
are not obsolete by a long long long way and remain the only way to
guarantee the properties required in some part processes if they werent
id be out of a job, but im afraid from my production and development
programme schedule im fully booked up for the next 3-4 years


depending on your application there may be other methods of
manufacture, forging is most definitely the strongest if carried out
correctly but beware of certain pitfalls ,you can over engineer a part
and machine it rather than optimize the part (ie for strength to weight
or fatigue)

without divulging the application your taking a long shot asking a
question like this if you need some more advice i would try to let a
bit more info go
or contact someone directly for a private discussion if you feel the
need drop me a line

 

Thanks Mike and all so far for contributions.

I'm not trying to be sectretive about the part but admit to keeping
reasonably quiet about working on military stuff. Anyway, the part I am
looking at has traditionally been made as a forging. I have seen the
part and drawings of it.

In my design, strength and low mass are certainly crucially important
but at the end of the day cost is all. The part is likely to be made in
large numbers i.e. 10,000 plus so machining from solid sounds tedious
and probably expensive especially as the shape means it comes out of a
large block of metal to start with. It is very likely that the
prototypes will be machined or rapid prototype cast and then machined.
The prototypes may not see the full environment so casting wouldn't be
such a strength issue.

I may just have to design the part as a group of machined parts that
can be mated to reduce the machining effort.

 

no problem as far as i can see is cost in our uk cost led industry
there is a great deal of not harking back to the good old days and more
leaning towards the cheapest quickest which doesnt turn out to be as
cheap or quick in the long run

i can send you the details of a company that can at least take a look
at his and give you a much better idea of what costs will be incurred
they specialise in forging turbine blades and a whole host of other
high strength parts

 

Hi Mike,

Details of any companies welcome. Can you let me know who?

Thanks

 

We used a LOT of them on the C17 Globetrotter.
IIRC Forgings are a bit stronger than other forms of
stock too.
Though I've also made other parts from plate for
somewhat similar applications on other aircraft ....

The cost of machining away all that extra stock is
high, as is the cost of all those pounds of nice Aluminum
(or other) alloy you just turned into low-value chips
(plus the costs of sweeping it up & packaging it
for disposal). It can also drag out expensive cutting
fluids, or become toxic waste ($$$$).

 

Hi Mike,
how do you guarantee the properties of a forging when Mil Hdbk 5 does not
differentiate between a forging and a machined part when giving allowables
for the material, even the fatigue SN curves for forgings and machinings
are the same.
If you can reference some data on values for forgings it would be great as
we are replacing forgings with machined parts all the time on older
aircraft.
I have not found any substatiating data to confirm that forgings are better
than machinings, although I was also raised with the notion that forgings
were better due to grain flow.

 

http://hip.bodycote.com/

http://www.azom.com/details.asp?ArticleID=924

http://www.hitchiner.com/HIMCO/HIMCO_Library/3D4_LHIP_Process.pdf

http://hipna.bodycote.com/index.asp?sid=process&content=process.asp?ID=247

 

Hi Cliff,
Well you guys are proving me wrong, I haven't worked on aluminum forgings
used in airframe construction (civil) for years. Titanium and PH series cres
for landing gear and engine mounts yes, but not aluminum.

 

You won't find it. It is usually proprietary.

 

cant quite figure your email

 

same here not for a few years a lot of
6.4eli recently and some aluminium mainly for defence and motorsports
i will try and post some data for the alloy from our database

whats your email

 

Hi all again,
It's clear that there is a lot of knowledge about this subject here.
Without wishing to drag the thread out too long, if I were to cast the
part in production, what recommendations could be made for a cast alloy
and heat treatment as close as possible to machined from stock
material?

Flynt