Sheet Metal Bend Parameters

[sbriar1]

I am desigining a Sheet Metal box (.015 thk material)that will be made with a CNC Bending Machine.
When I turn this into a sheet metal part using "Insert Bends" I am not sure what I can get away with on the "Bend Parameters" "Bend Radius", using .015 thk steel what would be a safe radius for most shops, I would like to keep the radius as small as possible without causing much trouble for the shop producing this.
I have attached a PDF of the box

Steve

 

[CorBlimeyLimey]

The best thing you could do is talk to the CNC operators. Find out what tooling they have, and design with that in mind.

No point in specifying a 1/64" rad bend if the smallest they have is 1/16". In some cases, special tooling may be required, but that will add costs to the product.

 

[TheTick]

Usually radius=thickness is safe. Some places go to 0.5T, but there are tradeoffs: strength, material softness, grain direction.

Bend factor does change with bend radius. Usually about 0.35 for 1008 steel.

 

[Updraft]

As a design guide you would usually want to use a bend radius that is at least equal to the material thickness; in the aircraft industry the minimum bend radius is 1.5*thickness. HOWEVER, this is only a guideline for good practice and not a recommendation for the actual value. CBL is correct in that you need to contact the fabricator and see what tooling they have. Your material is thin at .015", but a lot of shops have 1/16" as their minimum nose radius on their tooling. The CNC equipment relates to accurate locations of bends and amount of bends (angle), but does not directly have anything to do with inside bend radius flexibility.

- - -Updraft