Help designing a forging die

[jeffescott]

I am hoping that this die stands a chance of working.  It is a very small part the blank will be 5mm dia by 10.6.

I have straight edges so for removal I have air channels...or perhaps pin channels to hammer the pin out.

Any comments are welcome....including better ways to make the part. 

The pin is component pin shape...the blank is component pin blank.... the die is two bodies in component pin die. 

[MRWakefield]

Ok, a few questions and observations:

1. Are you hoping to do this cold (room temp) or hot? Titanium alloys are very difficult if not impossible to bulk cold form/forge.
2. You will most likely have great problems (if not impossible) backward extruding the long thin tube.
3. You usually have a punch and die setup. The punch fits inside the die rather than how you have it with the two halves coming together face-to-face. If there is any flashing between the two faces the forces increase exponentially as it tries to squeeze a wafer with an ever increasing area and decreasing thickness. This can be mitigated with some relief applied to the two faces but is less than ideal and is avoided if you use the punch & die setup as described.
4. Geometry like this would usually be formed in stages.
5. This type of problem is usually simulated in FEA software such as SFTC Deform or MSC Simufact for example.
6. Forming/Forging is a very specialised subject!

Hope this helps!

[MRWakefield · Accepted solution]

There's a good book on forming here.

[jeffescott]

I am glad i asked will get the book.

Yeah think hss steel die at 400c. Ti red hot with torch.  The ti turns blue after water quench.

thanks alot. Will try again.

[MRWakefield]

You'd be much better off using a hot-work tool steel that's specifically designed for hot forging rather than HSS. HSS is great for cutting tools but doesn't have ideal properties for hot forging tools. You might find H13 a suitable choice.

I'm sure you've already looked at a datasheet for the Ti alloy, if not you'll find one here on Ti-6Al-4V this gives some info on forging temps etc. Note that very often when 'forming' is talked about it is often sheet-metal forming, not bulk forming so you need to make sure any recommendations are applicable.

We use the SFTC Deform software at work and up until about a year ago I had a licensed seat so I could have run a simulation for you. It would have shown material flow, stresses, and the force required etc. Unfortunately my seat wasn't used very much so the license wasn't renewed (I think it's £8k-£10k per annum per seat so I can understand why!).

Is there a reason you want to forge these and not machine them from solid bar?

[jeffescott]

Really just because i dont have a lathe.  I have been making the pins from 304 set screws and filing them on my drill press then bolting to an arm.   Heavy and inaccurate.   Also not very hard.   Need to go to a rivet set up.  Also i am getting pretty good at hot bending ti gr 5 springs.    These are for backcountry ski bindings, and are the primary wear item.

[MRWakefield]

Ok, I just wondered that's all, as I'm not sure you'll be able to forge these very easily (if at all). Anyway, good luck with it, don't forget to let us know how it goes or if you need any further help.

[jeffescott]

Thank you much failure is always an option.   I have some pins that appear to be made from a high chrome alloy.   They also appear to be forged.   

[MRWakefield]

It would be really interesting to have a forging simulation done to see whether it looks like a total non-starter or whether there's some possibility of it working. I'll have a word with one of the engineers at work to see if he can run some simulations for you. It would satisfy my curiosity too!

I'm not at all familiar with the part or its application so it's difficult to give any advice on alternative materials etc. If it needs to be wear resistant perhaps a hardenable steel might be a suitable alternative if the Ti alloy turns out to be a no-go.

I'm off to bed now... it's almost 01:30 here!

[MRWakefield]

I've managed to get a couple of simulations done. I simplified the tooling to facilitate the simulations and made some modifications to make the die fully enclosed. In reality you'd need to have an ejector (probably bottom as well as top) to eject the part from the tooling. Both simulations were configured with the tooling at 400°C and the Ti billet at 930°C (recommended temp I found somewhere for hot forging Ti alloys).

Here's a link to the two simulations:

Notice that the force applied to the punch in both cases exceeds 70kN (~7,000kgf). The maximum load is when the point is filling and thin-walled tube is being backward extruded (as is to be expected). The simulations don't consider tooling strength so it's quite possible that the tooling might fail under these loads.

I did a quick search and found this article regarding the wear resistance of Ti alloys if it is of interest (spoiler alert - it's not very wear resistant!).

Anyway, I hope this helps. If you have any further information related to the rivet and its use it might help in recommending alternative materials or methods of manufacture.