Stainless laminate machining. 1

[rwild]

Hello all,

I am looking for some tips on machining .250 thick AMS-DTL-22499 Comp 3 Type 2 Class 2. Dilling and milling this material without it delaminating has been a challenge,and waterjet is not an option for us. Any thoughts on the type of tooling, feeds and speeds, processes (helical entry, ramping etc.)would be appreciated. Thanks for your help.

 

[MikeHalloran]

3. Clamp it tightly between sacrificial plates and machine the stack.
2. If volume justifies the tooling and the holes are not too small, fine blank it.
1. Purchase it in the exact shape you need.


Mike Halloran
Pembroke Pines, FL, USA

 

[MikeHalloran]

Addendum:
I have no idea how the anisotropy or the interlaminar goo will affect the process or the results, but you should try engaging a laser cutting service to take a whack at it.



Mike Halloran
Pembroke Pines, FL, USA

 

[btrueblood]

I like Mike's idea (has he ever had a bad one?), but would advise trying a water jet first instead, less likely to cause inadvertant welding of the plies/layers along the cut edge.

 

[rwild]

Thanks Mike.

 

[MikeHalloran]

I've had a >>>>lot<<<< of bad ideas, but someone else paid for correcting or burying most of them, and now I just talk about the few good ideas I've had. ... or stolen.

I have no direct knowledge of the process except as a remotely located customer, but microscopic examination of laser-cut stainless edges suggests that the process involves ablation, i.e. the photon cannon shoots a burst that locally heats a small quantity of metal to its boiling point, so it sort of ejects itself, leaving a crater, which the next burst deepens, etc., and then the beam or the part is moved by a spot diameter or so and the process is repeated, sort of like cutting a sheet by peck-drilling a line of adjacent holes.

I think they use a different process for laser welding, so I'm guessing the probability of the laminae being welded to each other is rather small, or the resulting welds will be weak enough to separate by hand. I'm more concerned about whether the beam can be adjusted to cut both the stacked laminae and the thicker sheet that comprise the sbuject material, which is why I suggest trying a few.

I have had a lot of meterial laser-cut, mostly by two different contract houses, and I hve never had to actually visit either facility to figure out what the hell was going on, because the resulting parts were almost always supplied clean and to my spec, and the few problems we encountered were ironed out over the phone. I can't give a higher accolade to a vendor than never having to visit them.






Mike Halloran
Pembroke Pines, FL, USA

 

[dvd]

My experiences with blanking of laminated materials is that there was a lot of die roll. I think that the burr may be eliminated with fine-blanking, but I still think that there will be a big radius.

I don't understand what is supposed to be so great about this laminated stock anyway: can't a shim package be produced with better results and less hassle? Laser cut shims of a few thicknesses that will produce total thicknesses in .002 increments and provide a chart or spreadsheet that tells the assembler how many of what thickness to install.

 

[MikeHalloran]

We may be witnessing the twilight of lamshim technology.
Its virtue is that you only have to buy, stock, and ship one part number, but the blanking and laminating does add some inherent expense. Two mil stainless is no fun to cut and deburr.

Laser cutting, OTOH, allows one to supply a number of shaped shims as a sheet, from which they may be torn or cut apart as needed, even including part numbers and ancillary information on the web between the parts.

For an intriguing example of lasercutting's potential, you can find images on the Web of Kevin Mitnick's business card, which appears to be laser cut of stainless, and in addition to his burned-in contact information, contains a tear-out set of lock picks.






Mike Halloran
Pembroke Pines, FL, USA

 

[racookpe1978]

Stamp cutting at least pushes all of the lamination layers together, rather than pulling them apart.

When (if) milling laminations, try to set the cutting head rotation so the cutting force does the same: pushing the stack of layers together rather than pulled apart.

 

[berkshire]

I have never done this job with stainless steel shims, but used to make custom shimstock from 1/2" thick .005" layer aluminum shimstock.
We had all of the problems you describe, fuzzing, splitting, total delamination. Our solution at the time was to find a dead area where we could drill small holes through the shim plate, then attach hardened steel filing plates by through bolting.
We would then use an air powered hand router with a double helix upcut down cut bit to rough off the excess material, then file the product to final shape. I realize with stainless you are not going to be able to use a router, but a double helix down cut upcut mill cutter, might do the same job.
B.E.

 

[Amaz]

My suggestion is wire edm.