Non-Conductive additive to prevent cobalt leaching?
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    Default Non-Conductive additive to prevent cobalt leaching?

    So I'm doing some research on cobalt leaching, and specifically ways to prevent it. I've found some options to do so, but it appears they are all conductive materials, so I would not be able to add them to a dielectric fluid in an EDM machine. (It appears they are more for, say, ultrasonic cleaners.) Has anyone had success in finding a cold-water, non-conductive additive to prevent cobalt leaching, or perhaps even a method I'm not thinking of?

    Appreciate you guys!

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    If I remember the best way to avoid Cobalt leaching is to run a fast rough cut then make a few skim passes. This should remove or greatly limit the occurrence of micro cracking. You could also find out what percent of Cobalt binder is used in the carbide you are cutting, the lower the number the less chance of micro cracks occurring. Also, look into the power supply of the machine, ac machines put less heat into the cut and limit Cobalt leaching as well.

    Personally the only experience I've had with wire cutting carbide was cutting endmills to make pins. If you are cutting punching dies or the like and you want more info I'd suggest getting in touch with an application engineer for the make of your machine, I've suggested this in the past.

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    Quote Originally Posted by Ishira View Post
    or perhaps even a method I'm not thinking of?
    Two main options come to my mind:
    - use an Wire EDM oil machine,
    - there are special carbide grades especially engineered for WEDM (e.g. boehlerit MB10EDM or generalcarbide 813CT)
    And of course keep the material as short as possible submerged.

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    Also keep in mind that cobalt leeching and cobalt depletion in EDM cutting are two very different things.

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    Quote Originally Posted by CarbideBob View Post
    Also keep in mind that cobalt leeching and cobalt depletion in EDM cutting are two very different things.
    Oh? What is cobalt depletion and how is it different?

    The issue we're faced with is cutting material submerged for many hours at a time, and whichever effect it is, is causing the material to become non-conductive after... a while? The time has not yet been measured, I never have a free machine to do the science with. Whichever one that is, is what I'm attempting to hinder.

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    Ishira,

    Deionized water is an enemy of carbides, causing electrolytic corrosion (leaching) of the binder materials. Oil dielectric is better because it contains little oxygen to support this corrosion.

    Click the link to go to my article on EDM'ing carbide within the EDM Today archives for a longer read. 2014_Spring_Feature

    Let us know of any improvements you make.

    Bud Guitrau
    Feature Writer
    EDM Today Magazine

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    Hi Bud:
    I took the time this morning to read through the articles you referenced above, and once again I am struck by how well they are written and how informative they are.
    I learned a lot to add to the few bits I was already aware of. so thank you very much for what you contribute to the EDM world.
    I have always been impressed by the breadth and depth your knowledge; I am deeply appreciative of your willingness to share it, and I want you to know that.

    Cheers

    Marcus
    Implant Mechanix • Design & Innovation > HOME
    Vancouver Wire EDM -- Wire EDM Machining

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    Thank you for the nice comments, Marcus. Iím glad to learn Iíve been of some help.

    As for my sharing of info... thatís easy. Iím trying to pay it all back.

    I have been extremely lucky throughout my entire career, enjoying patient instructors, bosses, mentors and coaches. From serving an apprenticeship, to shop-owner, through middle-management and executive positions Ė all of them were huge learning experiences. I got to travel the world and learn from many people much wiser than me.

    In this light, for me to accept and absorb all of this knowledge and not share it with everyone would be the height of selfishness and an insult to all who helped me along the way.

    Iím glad you found the article on carbide of some value. Browse the rest of the archives for more. If you canít find what you are looking for, let me know and Iíll e-mail it to you.

    Thanks again for your kind words.

    Bud

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    Quote Originally Posted by Bud Guitrau View Post
    Thank you for the nice comments, Marcus. I’m glad to learn I’ve been of some help.

    As for my sharing of info... that’s easy. I’m trying to pay it all back.

    I have been extremely lucky throughout my entire career, enjoying patient instructors, bosses, mentors and coaches. From serving an apprenticeship, to shop-owner, through middle-management and executive positions – all of them were huge learning experiences. I got to travel the world and learn from many people much wiser than me.

    In this light, for me to accept and absorb all of this knowledge and not share it with everyone would be the height of selfishness and an insult to all who helped me along the way.

    I’m glad you found the article on carbide of some value. Browse the rest of the archives for more. If you can’t find what you are looking for, let me know and I’ll e-mail it to you.

    Thanks again for your kind words.

    Bud
    As moderator I'd like to invite you to comment more often, between Marcus (an excellent resource and always willing to help) and I we can cover a good amount of stuff, but there's ALWAYS room for more knowledge. Such as in this case.

    In other words, don't be a stranger

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    Apologies for the couple days delay, I was too busy fangirling over Bud commenting on my thread. Thank you so much for taking the time to stop by and leave a nugget of your wisdom! I will absolutely look through that article again, I skimmed it once already the other week, but I really ought to sit and read it in depth.

    I wish I could convince my shop owners to convert to oil but I'm just unsure if that sort of suggestion will go over well. If I could compile some numbers to show them, perhaps I could sway their opinions... I will do some research.

    And of course thank you all for your input so far!

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    Plastikdreams,

    Thanks for the nudge... I'll try to check in more often.

    Bud Guitrau


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