Press tool material selection help please

[afrigot]

I am aiming to custom build a press tool for bending 1.2mm Alumnium sheet. The tool is for low volume production and will be doing approx 500-1000 hits/annum. I want to be able to machine the tool profile from solid using a standard 2 and a half axis CNC milling machine and have developed a suitable profile to achieve this. I require information for a suitable grade of steel and hardening process to make my tool. Thanks in advance.

 

[Metalguy]

You can get ~Rc47 with a simple post-machining heat treatment if you use 17-7 PH stainless. Easy to machine if you buy it sol. ann.

 

[NickE]

17-7 is gonna be rather expensive to make forming dies out of.

You might want to look into Kersite (or is it Kerksite). I think that its an Al-Zn-Cu alloy. Its commonly used for making prototype stamping dies.

Other wise what sort of tonnage are you going to be running? Do you have any draws in your forming tool?

500-1000hits is really not that many and I'm gonna guess that your Al sheet is relatively soft. You might be able to use a mold steel like P20.

goodluck
nick

 

[CoryPad]

Nick,

It is Kirksite.

Regards,

Cory

Please see FAQ731-376 for tips on how to make the best use of Eng-Tips Fora.

 

[NickE]

thanks

 

[EdDanzer]

We have used 4150 HT for proto type tools if used with a deep drawing lubricant. For greater tool life carbo-nitride E4340.
The Machinery’s Handbook lists “S” as shock resistant steel, “O”, “A”, and “D” as cold work tool steels.
Because of cost of the material, and the cost of heat treating tool steels we experimented with carbo-nitriding E4340 and found it an excellent substitute. We have even made broaches for low volume broaching of E4340 parts.

 

[metman]

For the quantities you need, Hot Rolled Mild Steel will work just fine. And better yet you can use Aluminum Alloy if you use a product called NoMar which is a thin (.020"?) sheet of rubber material. The NoMar is placed between the the die and the workpiece to prevent scuffing/galling.

We use aluminum and mild steel tooling all the time for forming aluminum sheet within the thickness range you stated.

Hot Rolled Steel is better than Cold Finished for this application because it has less residual surface stresses and therefore distorts less during machining.

Jesus is THE life,
Leonard