Wire EDM parting advise

[John_Genesis]

Hi all,

I'm pretty new to wire EDMs and running an Agie Cut2000. I am wondering what are the best practices for parting off and catching small parts.

Do you just let them fall in the tank? I'm concerned that it will knock the lower head out of alignment.
What I was taught to do was hold everything with magnets so they won't fall in the tank but sometimes the part will shift and cause the short circuit and I have to stop the machine every 3 mins.

any advise would be greatly appreciated

 

[toolmaker96]

More magnets. We purchase all sizes/thicknesses of rare earth magnets from McMaster. If that is not possible, can you leave a minimal enough tab, that you can just push the pats off the tabs? Are you burning die or punch shapes?

 

[plastikdreams]

99% of the time I let the pieces drop. Most of the time I put a m00 after the parting cut to make sure the piece is clear from the workpiece.

 

[plastikdreams]

I use tabs but I tend to not rely on them when the part is critical. In that case I run a 3 side profile and then a parting pass. This ensures there is no shifting due to flushing. I'm about to do this at work, 3 sided profile then flip 90° and cut 7 parts off.

 

[implmex]

Hi John Genesis:
There are many ways to hold male parts to allow a cutoff.
Here are a few:
1) Tap a hole in the waste stock and a hole in the part and put a strap across..
2) Slip strips of business card into several places in the kerf and allow the water to make them swell enough to hold your parts.
3) Fill up part of the kerf with light cured dental composite or light cured nail polish and cure it in place. (or use hot melt glue or cold cure acrylic or Bondo)
4) Use magnets
5) Make a clamp that will allow you to pinch the waste and the part. (see picture below).
6) Glue or solder straps across the kerf
7) Clamp parallels at the top and bottom that cross the kerf
8) Let the parts drop in the tank
9) Cut until you just hear the wire begin to break through, then hit the STOP button and knock your parts free (The sound changes a lot as you break through so if you're quick you can catch it at just the right time.)
10) Cut half, flip the part so the kerf is partly on the table, strap the part and the waste down and pick up and cut the other half.

There are probably lots of others but those spring easily to mind.

Cheers

Marcus
www.implant-mechanix.com
www.vancouverwireedm.com

 

[SeymourDumore]

Unless the geometry and the weight of the slug does not allow a drop, I always part-off and let it fall.
Sounds like In your case both of those cases are met ( otherwise you would not be asking )

Make sure your cutoff happens at an absolutely known and programmed point!!!
IOW, know, with ABSOLUTE certainty when and where the part-off is going to occur!
If you know that, you can insert a STOP either right there, or just after by no more than .005-.01 or so.
That way your slug will fall without any risk to anything on your machine.

A bit more tricky situation is when you are doing production runs of multiple part cutoffs.
There you do not have the option for a STOP, therefore you must ABSOLUTELY assure that the slug:
1: CAN fall freely away from the head
2: WILL fall freely away from the head
3: Machine WILL NOT travel back to any of the areas where a slug might be.
4: The slug WILL NOT short out your wire and cause overcut on the part

There is a bunch more that I am forgetting, but as someone who is primarily a bandsaw guy of production parts, I can say that over the last 23 years I have
parted off a very minimum of a quarter million slugs, (either finished part or the remnant ), all with only a very very few close calls.

If you picture what will happen and properly plan for it, a slug should not be a cause for concern.

 

[plastikdreams]

Here's an example of drop out wire cutting. There are 5 of these plates, each gets a .125 x 1.000 slot in it. Start holes are drilled into the material slightly smaller than .125. When the wire cuts the slot the slug breaks into 2 pieces so it doesn't get stuck and falls clear. So the machine jumps to all 5 slots then goes back and cuts each piece off.

 

[John_Genesis]

Thank you all for the very insightful advice. I'll be putting them to good use.

I also realized than I can clean up my toolpaths to reduce that chances of having a short circuit scenario. There is a lot of subtleties to running an EDM well.

 

[precisionmetal]

John,

Tons of good advice above!

The good news is, the Cut2000 has an insanely powerful control that allows almost endless ways to cut a part (or handle a drop). I ran one for about 3 years at a large tech company, and while the early ones had some control issues (ugh), the versatility of the control was phenomenal.

In the years when I was in the wire business on my own (with an HSS170), I would say that if the parts I was making had even a very remote chance of having a problem with the drop, that was were my focus was on the part. I made quite a few very tiny parts that would run unattended, and quite often I would no-core some/all of the holes I was wire cutting just so I did not have to lose sleep! Granted... no-core is ridiculous for any decent-sized hole, but on small hole sizes I used that strategy quite often.

Have you seen what Fanuc does on their latest wire machines to handle a drop? They do some "shenanigans" with the current going through the wire, and somehow melt off some brass and fill the slot in whatever locations you want. Super clever.

PM