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  1. #1
    Join Date
    Apr 2019
    Posts
    2

    EDM COE less than stainless steel 316?

    Hi, I had my EDM crack on one or two of my tools that I make. I make tools for glassblowers. There is an EDM round 1" in diameter two inches long mounted onto a 3/8" OD stainless steel tubing, .039" wall thickness. The EDM is drilled about an inch up through the center of the round, and threaded with 3/8 - 24 threads. The stainless steel tubing is threaded to suit, and after being threaded into the EDM secured with a set screw and a lock nut. Once I tried bluing my handles by getting the tools up to 600 Fahrenheit in a kiln. Soaked them for about 30 minutes before ramping down. I noticed a couple of the tools the EDM had split. I'm thinking the stainless steel expanded more than the EDM putting excess pressure on the EDM causing it to split. Can anyone confirm this? It's high density fine grain EDM. Thanks!

    EDIT: Looks like COE for graphite is between 7 and 8.8, while 300 stainless family is between 14.9 and 18.7. Whoops! I guess I will have to test this last batch of tooling.
    Last edited by TorchHypnosis; 04-11-2019 at 03:48 PM.

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