How to decide die size from blank size
In tool and die design ,I want to know how to get die size if I have blank size of 250*200*3
The standard I have been using for metal is:
For Aluminum Alloy: Thickness times 15%
For Mild Steel Alloy (your material): Thickness times 20%
For Stainless Steel Alloy: Thickness times 25%
In your case, 3mm x .20 = .6 mm total (not per side)
Keep in mind, this factor number is what I have been using, you should check further to assure yourself.
Good luck with your project.