4140 getting magnetized during WEDM?

Just wondering if any of you have run thru this issue. We are trying to cut some 4140 that keeps on getting magnetized while we cut them.

We thought it was stress on the parts as it was pinching the wire while parting thru the cylinder but came to find the part gets really magnetized so the flat faces pull each other 'til they contact. After taking the 1st part out of the machine we couldn't really break the halves apart so we demagnetize them on the little bench top unit we have and that got them loose.

Just borrowed a magnetometer and found there is really not a magnetic field on the parts themselves but really just on the WEDM face cut. I also checked the parts before they went in and we have between 0 & 1 gauss.

Also checked on another batch of the same part number that I had to sub out and found no evidence of magnetization on them.

Any ideas?

Thanks in advance!

MMtz

Check out the article about residual magnetism and WEDM in the EDM Today article about Tech Mold in Tempe, AZ. I think it covers other issues with magnetic transfer and the EDM process.