Advice on using CNC Desktop Milling Machines for making punch/dies

[gpietersma]

I want to be able to make my own punch/dies to cut shaps from .015" steel. In the past I have contracted this work out to machine shops; however I want to make the dies at a lower cost by machining them myself. The dies would be faily small - 3"x5". The clearance we usually specify are .003" .

What I want to know is can a desktop CNC machine like the tormach or the CNC Jr. Table Top Mill make such parts.

Any advice?

Greg Pietersma

[kochevnik]

Bump.

I'm interested in this as well. Does anyone have any resources to point me towards on the web (or elsewhere) abouut milling punches/dies. I'm looking for an 'Punches and Dies For Dummies' kind of thing - what's the best material for making them, what kind of clearances for what types of materials, calculating punch pressures etc.

Any help/advice would be appreciated.

Thanks.

[gpietersma]

I have just ordered several books on the subject from Amazon. Some of them were quite expensive. I should get them today. I'll report on them soon.
Greg

[kochevnik]

It sounds like we are trying to do much the same thing. The shapes I have to cut are, at most 3" x 1" and I'm using 4130 Chrome-Moly steel sheet, .040 to .060 thickness. I haven't done anything yet as I ordered a Tormach and am waiting for it to appear.

Some things I've found, just on a cursory search - a basic calculator:

http://www.anvilfire.com/21centbs/ma...hing_steel.htm

I've also considered Greenlee dies (but I'm not sure how well they work)

[InspirationTool]

I'm interested in this as well.

Getting a good gap tolerance may require some practice to achieve. If you parts are +/-.001, then your gap runs from .001 to .005 if you were aiming for a .003 gap.

Also, I'd wonder about hardness issues. Are you machining the die while hard?

Can you run a grinder on one of these machines to grind to final size after hardening?

-Jeff

[kochevnik]

Originally Posted by InspirationTool Also, I'd wonder about hardness issues. Are you machining the die while hard? Can you run a grinder on one of these machines to grind to final size after hardening? -Jeff

I found this too :

http://www.thefabricator.com/Tooland...le.cfm?ID=1078

For me, the die/punch does not have to be of great hardness as it is being sold to end users who will only be using it maybe a dozen times and I'd like to stay away from using any other tool other than a mill (not sure this is possible but I can hope anyways).

[parttime]

Desk top CnC machines can hold the tolerances you want to hold if you machine with light cuts. The problem I've found with mine is that to keep the area free of chips, I have to tend to the machine frequently. This makes it imperative that I be around it when it's running. I've machines carbon steel and stainless with some success. Tools get dull fast though with stainless.

Have you considered sending parts out for wire edm? This can get you the .003" gap you are looking for on a blank die.

[ViperTX]

The thing to remember is that you need to heat treat the die and the punch....I don't know what you're paying for dies....but when you figure your labor, etc.....you may find that it's cheaper to out source the work....

[karamitrov1]

Try with HAAS TM1 or HAAS ofice mill.
This is not an easy job as it seems expecialy if the tools need a close tolerance and if they need to be exployted for long series of parts. To achive a great tolerance try to mill finish small chip of the die after heat treatment(you can find tools for that type of miling at SANDVIC or try with SARTORIUS, i use sartorius tools) Try to use 4226 material ISO standard(or OCR12)
karamitrov1@yahoo.com

[budP]

it is being sold to end users who will only be using it maybe a dozen times

How do you know that this is the case?
Selling a part that only has a life time of less than a dozen times used is probably not a good business plan, it will bite you in the end with bad press from the bad quality.

budP

[roninB4]

Too many variables to give a complete answer to this. How large is the largest die section? What is "does not have to be of great hardness" in real numbers (Rc)? How complex are the die sections/punch plate/stripper? Are you using a box stripper? Are there any bends to the finished part? If you would include a graphic rep of the part/die then maybe one of us could give a better answer.