Forging a low carbon steel hub

[Tmoose]

24" Ø, 9.5" long, 11" Ø at small end. The 11" Ø extends for about 3.25" to meet a cone shape.
Stepped bore that will be finished to 4.5Ø and 6.5 "Ø. Call it a nominal 4.5" bore straight thru.
The part will be pretty much finished all over.

A forging house just said this about forging our part -
"the type of forging you are looking for is better suited for a closed die forging manufacturer. We are an open die manufacturer. It would cost you a lot more to buy something like that from us, than someone who is a closed die manufacturer… "

That forging house specializes in pressure vessel connections, flanges, nozzles and wellhead components. Thin walled rings with flanges as I picture them.

In my mind's eye I've been picturing that unless someone already had dies close to our odd net shape, a few dozen strokes with an open die set up would have pounded and squeezed a shape within a few inches of our net shape.

https://www.youtube.com/watch?v=YobXFODkp50&feature=emb_rel_end

How far off base am I ?

thanks,

Dan T

 

[mfgenggear]

quantity

 

[tygerdawg]

Is this the drawing that you provided for evaluation? Then I'd agree with the forging vendor: closed die. Even though no tolerances are provided on the drawing, there are features there that require closed die.

If you wanted a fat-tolerance blank that sort of resembles the finished part, suitable for subsequent processing to net shape, then maybe so. You'd need a realistic blank drawing though.

Many textbooks and reference books on forging are out there for you gain more insight.

TygerDawg
Blue Technik LLC
Virtuoso Robotics Engineering

http://www.bluetechnik.com

 

[Tmoose]

For my example for my BFFs here on Eng-tips I removed the finished tolerances. I figured a bore finished to +.003"/0.000 didn't really add much to a forging drawing. Maybe a note saying "finish" all over would have made more sense. Sorry.

Hi Tyegerdawg,
Which features require closed die ?

thanks,

Dan T

 

[mfgenggear]

@TMoose (Dan)
unless there is a requirement for thousands of these flanges, it will be quicker and faster to open die forgings,
rough machine Heat treat then finish machine. it will be quicker and faster.
and if the allowable stress can be met with forged bar, it will be more economical
and even faster lead time then net near forging if it's for a small quantity.

 

[tbuelna]

Tmoose,

What is the reason for machining your hub from a forging. Is it to reduce machining time/cost? Is it to reduce the amount of raw material required? Is it to improve the material's metallurgical characteristics?

There are vendors that can produce a hollow flanged hub forging fairly close to the shape you require, using simple open dies and tooling that they may already have in-stock.

https://www.scotforge.com/Products/Hubs-and-Tooled-Forgings

 

[Tmoose]

The hub needs to be very weldable, hence low carbon steel.
No real strength issues.

Forging vs casting vs carved from huge billet - price and availability rule. Especially price.

thanks all.

Dan T

 

[tbuelna]

There are some rapid prototype processes that might be cost effective for your application, depending on the quantities involved.

There are large additive manufacturing machines that build up material using MIG welding. It's lower cost than any other additive manufacturing process. For a small qty of parts, one option would be to torch cut the flange ID/OD profile from 6"(?) plate, then add the smaller diameter shaft section using a MIG additive process. For a single part you could build up the entire part preform using the MIG additive process.

https://www.voestalpine.com/welding/Brands/Boehler-Welding/3Dprint

There are also large machines that 3D print sand casting molds. A shape like your hub should only require a simple two piece mold.

https://www.exone.com/en-US/3D-printing-systems/sand-3d-printers

Hope that helps.

 

[TugboatEng]

Can you make the hub in two pieces, a 10.5 inch bar with the larger diameter shrunk on or welded on?

 

[Tmoose]

thanks all.

Dan T

 

[DAVIDSTECKER]

depending on the definition of "Forged" you may be able to get a round burnout from 10" plate, the hog out your part.