CNC sheet cutting comparisons: laser, router, punch, waterjet, wire edm...

[InspirationTool]

I recently ordered a small batch of stainless sheet parts and the best quotes were from people with laser cutters. As I learned more about laser cutting, I realized:

1) Cutting things from sheet material is a fairly cheap way to do small production runs (50-500 items).

2) I don't know enough about the different methods.

What I would really like is a "CNC Sheet Manufacturing Guide for Wacky-Inventor-Types" book, but doubt anything like that exists.

Another option would be a spreadsheet showing each method and a series of attributes for comparison:

Material it can cut

And then, per material:

Max Thickness
Min Thickness
Accuracy
Smallest hole it can cut
Smallest slot it can cut
Smallest feature it can cut (how narrow a "fork tine" can it cut)
Any taper of cut (thinking plasma)

Relative cost of basic machine
Estimated cutting speeds

Does anyone know of any resources, or if I put together an online-spreadsheet of some sort, would people volunteer to fill in the blanks?

-Jeff

[roysol]

Hi Jeff, I'd be happy to cover the wire edm portion. I do a lot of prototype sheet parts that I cut as a stack. These are small parts with features and tolerances that do not lend themselves to laser or waterjet. If you can open dxf files I can post some examples.

Roy Solomon

[InspirationTool]

That would be great!

I'm especially interested in taper tolerances. My understanding with laser and waterjet is that the tolerances run _roughly_ .005 per inch vertically.

I have some parts that are 3/4" high with .035" wall thickness that I'm looking to get done.

Also, how does your edm work with multiple inside cut-outs? I know some edm's will self feed on existing holes. Are there any that combine a sinker for hole formation, and then wire for profile cutting?

Thanks!

-Jeff

[roysol]

Jeff, I have cut parts as tall as 8 inches that were straight within 2 tenths. Most modern machines auto-thread, as does the one I currently run (Mitsubishi). There were a couple of attempts to integrate a "hole popper" on to a wire edm in the mid 80's. This concept did not catch on for a variety of reasons. I usually have a stack of sheets drilled, some times our strippit turret punch press will pierce the start holes, then blank the outside. I used to screw stacks together on a base plate, lately I"ve been having our fab department tig weld up the sides, that works pretty well.