Thread: Does Wire EDM change the temper or properties of metal?

Well jay131,
You started this mess, and I'm glad you did. Both sides of this discussion have presented legitimate arguments. Although I'm not a edm machinist or a metallurgical engineer, edm technology is a vital part of our manufacturing base. My business relies on these guys that choose this work.

otrlt
ortoolworks

I realize this is an old thread but maybe I can get some replies. I'm a quality tech that works in a metlab. We do not have an on-site metallurgist, so it either falls to me or we have to outsource it.
Most of my job entails cross-sectioning a part and measuring weld penetration or hardness. Sometimes if a part is too thick or awkward, it will be sent out to be edm cut. I'm also curious as to how much this changes hardness and grain size near the cut surface.Is this something I should be concerned with or not?
Samples are usually mounted in acrylic then polished. At a minimum I would say .01" are removed during the polishing. I don't have a machinist background. If I'm understanding correctly, when they make an edm cut, the surface that is made is basically or "could be" recast. I have no idea if the outvender we use has a new or old machine.

The thing that I was googling the lead me here was we have this part that is aluminum 6061 welded together. Not sure of the material in the filler rod.(not a welder either) I started noticing little microfissures between the weld HAZ and the parent material when the cross section was looked at under magnification. This part was actually cut with an abrasive saw. Initially I thought maybe the vibrations from the saw or possible stress from the vise that the part was placed in to hold for cutting. I was considering an edm cut instead. Hoping this attempted solution wouldn't introduce another problem. At least if it does, would like to see it coming.



On a side note. We have a machined part that we make out of some 300 series stainless. There is a real small hole in the part that we don't machine so it is sent out to be edm'd. I know that after the edm operation, parts are then sent to another vender to have an "eddy current" test done. The drawing for the part has a note specifying the eddy spec and goes into the max allowance for the cracks found during said test. Before reading this post, I had never heard about aerospace being real strict when it comes to edm machining.(above my pay grade) makes sense now as to why those parts have to have that eddy test done.

Sorry I know this post was all over the place. I kept thinking of more questions as I went. I probably forgot along the way what my original question was. 🤔

Originally Posted by nitpicker

I realize this is an old thread but maybe I can get some replies. I'm a quality tech that works in a metlab. We do not have an on-site metallurgist, so it either falls to me or we have to outsource it.
Most of my job entails cross-sectioning a part and measuring weld penetration or hardness. Sometimes if a part is too thick or awkward, it will be sent out to be edm cut. I'm also curious as to how much this changes hardness and grain size near the cut surface.Is this something I should be concerned with or not?
Samples are usually mounted in acrylic then polished. At a minimum I would say .01" are removed during the polishing. I don't have a machinist background. If I'm understanding correctly, when they make an edm cut, the surface that is made is basically or "could be" recast. I have no idea if the outvender we use has a new or old machine.

The thing that I was googling the lead me here was we have this part that is aluminum 6061 welded together. Not sure of the material in the filler rod.(not a welder either) I started noticing little microfissures between the weld HAZ and the parent material when the cross section was looked at under magnification. This part was actually cut with an abrasive saw. Initially I thought maybe the vibrations from the saw or possible stress from the vise that the part was placed in to hold for cutting. I was considering an edm cut instead. Hoping this attempted solution wouldn't introduce another problem. At least if it does, would like to see it coming.

On a side note. We have a machined part that we make out of some 300 series stainless. There is a real small hole in the part that we don't machine so it is sent out to be edm'd. I know that after the edm operation, parts are then sent to another vender to have an "eddy current" test done. The drawing for the part has a note specifying the eddy spec and goes into the max allowance for the cracks found during said test. Before reading this post, I had never heard about aerospace being real strict when it comes to edm machining.(above my pay grade) makes sense now as to why those parts have to have that eddy test done.

Sorry I know this post was all over the place. I kept thinking of more questions as I went. I probably forgot along the way what my original question was. ��

If you are removing .01" or more, you should be removing all of the recast and remelt layers of any EDM process. Your etching process after the polishing should remove a tiny bit more as well. Since EDM is a thermal process the affects will be closest to the EDM eroded surface.

Fyi
Im not saying which EDM machines but y'all can probably figure that out lol