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Machining Tungsten Carbide - advice needed!

S

Sethur

Plastic
Joined
Jun 11, 2018
Hi

I'm new to the forum, I've a fair bit of mechanical experience but ultimately I'm not a professional.
I'm seeking some advice on machining Tungsten Carbide, i've looked across other threads on the forum and found a few useful pieces of information, but i'd just like some clarification.

I'm trying to turn a ring from a 20mm TC rod, using a basic lathe at work, i've a number of indexable lathe tools and a few PCD inserts for these tools.
I'd managed to turn the outside of the work and put a small radius on the work using a ball turner while practicing but i'm now at a point where i'd like to really refine the process and make the final piece.

The problem:
I need to bore the work out, I have been under the assumption that for best results i'll need to find a PCD coated drill bit, my intention is to drill a 10mm hole just large enough to get my boring bar in and work from there.
The 10mm PCD drill bits that my local supplier sells are around £100, i've befriended a guy at the supplier who has been helpful, he holds very little confidence in the drill bits working, says they're very hit and miss with TC, doesn't even want to risk selling me it!

Really i'd like some advice to perhaps make me feel slightly more confident about spending that much on a drill bit that may or may not work. (The drill bit is a YG - DI7430.)

Also any advice regarding TC would be brilliant (lathe speeds, lubricants, cut depth, feed rates, the lot).
Cheers,
S
 
You need diamond coring drills, like these: 12 Pcs Diamond Hole Saw Drill Bit Hollow Core Set Glass Extractor Remover Tools 6188843 | eBay Yes, they're cheap junk, and you'll need multiples of the right size to work, but they're vastly more sensible than a PCD tipped drill.

Plenty of patience, low force drilling with a light kerosene or water for lubrication and frequent flushing. If using kero or light oil be sure to keep an extinguisher at hand, minimize quantity you're using.
 
You do realise the cobalt binder is a carinogen and won't be at all good to have spending a long time on your finger if this is std tooling grade material. My understanding is the jewelry folk press there parts with a different binder.
 
adama said:
You do realise the cobalt binder is a carinogen and won't be at all good to have spending a long time on your finger if this is std tooling grade material. My understanding is the jewelry folk press there parts with a different binder.
Click to expand...


Hiya

Thanks for the reply, I was aware of the problems with cobalt, I need to make sure the TC i use for the final piece is free of cobalt, if you've any recommendations on grades of TC feel free to share?
How do you mean, press their parts with a different binder? Are you referring to the sintering(?) process usually used to make the stock?
Thanks pal!
 
Milland said:
You need diamond coring drills, like these: 12 Pcs Diamond Hole Saw Drill Bit Hollow Core Set Glass Extractor Remover Tools 6187788843 | eBay Yes, they're cheap junk, and you'll need multiples of the right size to work, but they're vastly more sensible than a PCD tipped drill.

Plenty of patience, low force drilling with a light kerosene or water for lubrication and frequent flushing. If using kero or light oil be sure to keep an extinguisher at hand, minimize quantity you're using.
Click to expand...

Hi Milland

Thanks for the reply, I'd seen a few tools like that before but wasn't sure whether to go that route, as im unfamiliar with diamond tooling, i couldnt believe they could be any good when there are £200 & £300 drill bits out there etc (I was just a little skeptical). I'll take a closer look into them, thanks for the cheaper alternative!
Thank you also for the advice on the kerosene oil etc, i'm sure the extinguisher will go down well at work! Mind you, everyone is pretty relaxed here :)
Cheers,
 
Triaged said:
I bought mine from Amazon for $22. It has a Nickel binder.
Click to expand...

Yikes, some people are seriously allergic to that also, generally anything outside copper (it stains your skin but does not cause a allergy type reaction) silver, platinum gold and the surgical grade metals your playing russian roulette with people wearing the stuff. Nickle in particular is something people seam to build a allergy too, can be fine for a very long time then it kicks off and it can get pretty nasty.

15+ years back when the internet was not as common, i had a pretty good line going in custom 316 jewelry, but it really was nothing you could wear on your finger. More than a few people got sent my way because i would reproduce what they needed in real 316 and passivate it to a truly great finish to replace junk metal they had payed a hell of a lot for in some cases.

Don't discount the diamond cheap hole saw bits, not sure what they will do with carbide, but the cheap set i bought of the bay a long time ago keep on drilling. Have a 35mm one that's drilled through a half dozen concrete drive way bricks. key is keeping them cool and flushed, hence sensible speeds and regular withdraws and flushing, i like a simple trigger spray. Oh yeah as well as exotic stuff, they piss putting the hole in tiles in the bathroom too.
 
adama said:
Yikes, some people are seriously allergic to that also, generally anything outside copper (it stains your skin but does not cause a allergy type reaction) silver, platinum gold and the surgical grade metals your playing russian roulette with people wearing the stuff. Nickle in particular is something people seam to build a allergy too, can be fine for a very long time then it kicks off and it can get pretty nasty.

15+ years back when the internet was not as common, i had a pretty good line going in custom 316 jewelry, but it really was nothing you could wear on your finger. More than a few people got sent my way because i would reproduce what they needed in real 316 and passivate it to a truly great finish to replace junk metal they had payed a hell of a lot for in some cases.

Don't discount the diamond cheap hole saw bits, not sure what they will do with carbide, but the cheap set i bought of the bay a long time ago keep on drilling. Have a 35mm one that's drilled through a half dozen concrete drive way bricks. key is keeping them cool and flushed, hence sensible speeds and regular withdraws and flushing, i like a simple trigger spray. Oh yeah as well as exotic stuff, they piss putting the hole in tiles in the bathroom too.
Click to expand...

Hiya

I've just had an interesting conversation with a company that do custom sintering, so I may not even be in need of the drill bits after all, they work to a pretty reasonable price too!
Apologies, i wasn't discounting the suggestion at all, merely explaining why I had previously overlooked them :) Sounds like they've been a worthy investment for you so perhaps they're worth a shot (if i do need to drill this hole at all).
Really helpful information there about the allergies etc! Thank you for that, I have heard of binding the carbide with things like palladium & platinum before, perhaps this company will have some insight there, I'll see what they're able to do first.

Cheers pal!
 
Well feel free to let me know what the ray gun makes of it :)
Any information on nickel allergies particularly in relation to the very minimal nickel content in TC is now quickly becoming the focus of my googling!
Sure the $5 wont be missed to much :P

Genuinely interested to know the composition though if you ever find out. :)
Cheers pal!
 
Sethur said:
Well feel free to let me know what the ray gun makes of it :)...
Click to expand...
Ray gun says 11.3% Ni, 3.4% Cr, other trace, and the rest W. I have 2 and I'm not sure which is which and only had time to zap one. Says "MJ tungsten carbide white" on the inside. Maybe I'll die from nickel.
 
^ Its not the content of nickle that matters, its how long you wear it and how sensitive you are to nickle. One thing i can assure you, once sensitized, you' will soon know when you encounter it again. I know a finger ring is not as much a issue as the kinda stuff - locations i was dealing with is, even so, IMHO you would do real well to limit your exposure too it. Some of the people i made replacement jewelry for had had the same piece in there for years till it flared up.

When you have seen the tongue of someone suffering from a nickle allergy with a nickle bearing piercing in it, trust me, you will get it a lot lot clearer!
 
adama said:
When you have seen the tongue of someone suffering from a nickle allergy with a nickle bearing piercing in it, trust me, you will get it a lot lot clearer!
Click to expand...

Maybe it's due to having a lot of "involuntary" piercings, but I will never, and I mean never ever understand people who do this on purpose. I can just about tolerate one or two ear piercings, but more than that or elsewhere and I'm just "ughh...".
 
I wonder how deep X-ray fluorescence penetrates in these materials. It is possible the chrome is a thin plating.
 
Milland said:
Maybe it's due to having a lot of "involuntary" piercings, but I will never, and I mean never ever understand people who do this on purpose. I can just about tolerate one or two ear piercings, but more than that or elsewhere and I'm just "ughh...".
Click to expand...

If you ever end up with a partner with piercings and they know what there doing, trust we you will rapidly get it!!! Probably as much as should be said here, but there's reasons for some of these and there above and beyond looking odd to people such as your selves.
 
Apologies for the absence, just reading through some of the messages here, it's useful to see the mix of opinions here.
Reading around a lot, some of the best TC wedding bands, the true "top notch" ones, all pride themselves on using nickel instead of cobalt.
I've been under the impression that although they've been around in the background for a while TC wedding bands are a fairly new venture and perhaps not enough people have been wearing them for long enough to develop an allergy yet. Mind you, perhaps with the rise in divorce rates & fail marriages, prolonged exposure just isn't an issue to these people anyway :D

Triaged: Interesting to know the actual composition! Thanks for sharing that.

Is there anyway to actually test for a nickel allergy perhaps?

Many of the sites that discuss TC wedding bands seem to suggest the minute quantities make chances of allergic reactions pretty low. But we've no idea who has written these articles, it could just be a wedding co-ordinator with no experience of engineering/allergens :/
 
I don't think quantity is the issue, i think its more down to sustained contact. Piercings your body is trying to constantly heal and hence fighting it, add something irritable and its going to get real ugly fast. Finger rings probably are a lot less of a issue, but after seeing what i have, i would still question why this material? Theres so many other options out there that are proven safe. Why use a material that has known issues with human contact?

Interestingly industrial carbide might not even be all that bad, turns out theres some significant amounts of cobalt in false hips. Which seams kinda nuts when you look at the controls mesures that get put in place for industrial grinding of cobalt rich components - alloys.
 
Look for a preformed carbide ring of the correct grade. It'll be fairly close, both ID and OD, minimizing machining. I used to make "stick" drills from carbide rectangular blanks, solid for small sizes and silver brazed to round shanks if hole is large enough. Drilling is done at low speed. Turning was done with harder carbide, though grinding required for any sort of precision.
 
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