Part stacking - Fanuc c400iA

New job we just got and normally all of our Wire stuff deals with features on an existing part where milling is a challenge (medical). This particular part I believe is good for stacking. its an elbow shape with one outside wall having strait cut teeth. 6mm thick about 2" x 3". no internal features.

My question would be should I take a skim cut? based on qty. of the order and stock prep I'm thinking a stack of eight. Everything is ±.004" so no worries there but I worry about wire lag on the center pieces in the teeth... The fanuc has corner rounding built into the control and I know its a big sales pitch item but how effective is it? By not using this wire for a lot of thick and complex stuff should I be concerned with just a rough?

I am hesitant on the skim not because of time but rather the parts moving when i get close to the tab and then try and run back for the skim. Materiel is 17-4 SS and even though it is going to be in annealed state we have to mill it down to size from 1/4" so I know there will be at least a little stress built up in the material. Maybe multiple tabs?

Any Advice would be great! Seems like gravy work but I just don't want to run eight pieces and end up throwing them out..


Tom

Even without seeing a print I would recommend the skim cut. That material moves a good deal when you wire it so a little skim cutting will give you better results, both precision and finish.

I think if I was doing the job, I would put a 6mm plate in the machine with 8 start holes, do a rough and skim, and leave a decent width tab so I didn't get any movement. Run it overnight, and cut the tabs in the morning when I got to work.

The reasons for this approach are:
-- time spent prep'ing a stack is not trivial if you want a solid/tight stack
-- cutting stacked parts free at the end can be problematic, unless a nice clamp method fixes the parts/drops tightly to the outside when cutting the tab
-- putting 8 start holes in a plate and writing the program is fast
-- overnight cutting is (almost) free time, unless your machine is already tied up overnight or you are running 3 shifts


PM

Thanks guys for the responses! I defiantly learned a lot from this job. What I ended up doing base on your suggestions was do the stack of eight with a skim and rough combination.

I have thought of the the big plate idea but couldn't source the material. we used 4" x 6" x .25" flat stock. cleaned up, drilled start holes, and sized to 6mm which gave us 4pc per stock piece. tig welded the stack together and off we went.

For testing I took just one piece of stock and made just the rough. the part passed but was lacking a little on the overall quality in the teeth that one should expect from a wire. re-tested with a one pass around to the the start of the teeth and then took a rough on the teeth and back with a skim just on the teeth. Cut and threaded back in the start hole and went around the other way with one pass and ended up dropping where the teeth start. This method was the ticket. Decided our stack was worthy and took the chance on all eight and wallah good looking parts.

I was worried that during the cutoff it would be difficult to get them to all release but didn't even break the wire. had a clamp over the stack and that was enough.


thanks again!

Tom