Plasma Cutting Tungsten

[Scotty1]

The thought is to use tungsten plate (billets) in the range .250" -.125" To re tip drilling bits,
Unsweat broken inserts and rebuild bit profile (Mig/Stick)
Rough grind to shape
Cut new inserts Plasma (slight oversize) and sweat in
Grind bit to profile/rake etc with Diamond wheel
The cost of a New Bit 8" 4Way Chevron 4/1/2" Reg API =$1200 (May GET 200 Meters out of it if your Lucky)
Scrap tungsten/off cuts can be broken down and used to re tip diamond drill bits

Your Thoughts

[DaveO]

Hello, Scotty, and welcome to the Forums. I had to look up some of your terms just to figure out what you're talking about... just out of curiosity, are you rebuilding the bits for your employer, or as a service offered by your own business?

Feel free, of course, to respond with "That's proprietary, thanks for asking" but I'd be interested to see how the rebuild process goes. Congrats on the 250ex and cooler!

[jakeru]

You must be talking about tungsten carbide for re-tipping cutting implements (not pure tungsten, which would probably not hold up quite as well.) Is that right?
I've never tried it, but hear it can be silver soldered to steel nicely. Maybe brazed. That would be interesting to hear how a sheet of tungsten carbide might plasma cut.

Actually it would be interesting just to see a big sheet or plate of it.

[Scotty1]

Yes Tungsten carbide,the new tips(INSERTS) are just brazed in
I can buy in ready cut inserts but the cost is nearly the SAME as a new bit! They will give discounted price on over 10,000 pieces
As different size bits use different shapes/style inserts would be a lot of stock hanging around

Would a Plasma cutter do the job or have to go to LASER as some inserts are quite small?

Mainly my own bits

[hooda]

Hi and welcome aboard the good ship Everlast! If you're talking about tungsten carbide, then I think you're in for a letdown. Tungsten carbide, as a prepared raw material, I've never heard of it being available in plate form of .125"-.250" If such a material were available, my guess is the cost would be prohibitive to do what you aim to do. Tungsten and tungsten CARBIDE are 2 entirely different materials, and the carbide is some expensive stuff! Whet is the actual size of each insert, and how many are on each bit? If it's even in the REALM of normal, I can find you a good, cheap source for replacement inserts that you could sweat in and grind to shape, but to my knowledge, plasma would just make a mess, if it would cut at all.
Most, if not all tungsten carbide is actually powdered tungsten carbide blended in a cobalt binder, then pressed together at tremendous heat and pressure. With the temperatures associated with plasma cutting, you would most likely destroy the structural integrity of the binder, rendering it useless. IF you got it cut, the edges would crumble, and by the time you got to the good part, thermal shock would have made it so weak, it would be useless.
The only way to practically cut the way you intend to would be with wire EDM, which is expensive in it's own right. Or score a flat piece with a diamond wheel, then snap it on the score.
I have a bunch of old carbide endmills and a pp70. I'll try cutting one tomorrow. Let me know what size you need, and some closeup pics would be nice.

[Scotty1]

hooda thanks for your input,
This has been a concern from the start

Will give you more info and photos in the next couple of days
Regards

[Scotty1]

Hi and welcome aboard the good ship Everlast! If you're talking about tungsten carbide, then I think you're in for a letdown. Tungsten carbide, as a prepared raw material, I've never heard of it being available in plate form of .125"-.250" If such a material were available, my guess is the cost would be prohibitive to do what you aim to do. Tungsten and tungsten CARBIDE are 2 entirely different materials, and the carbide is some expensive stuff! Whet is the actual size of each insert, and how many are on each bit? If it's even in the REALM of normal, I can find you a good, cheap source for replacement inserts that you could sweat in and grind to shape, but to my knowledge, plasma would just make a mess, if it would cut at all.
Most, if not all tungsten carbide is actually powdered tungsten carbide blended in a cobalt binder, then pressed together at tremendous heat and pressure. With the temperatures associated with plasma cutting, you would most likely destroy the structural integrity of the binder, rendering it useless. IF you got it cut, the edges would crumble, and by the time you got to the good part, thermal shock would have made it so weak, it would be useless.
The only way to practically cut the way you intend to would be with wire EDM, which is expensive in it's own right. Or score a flat piece with a diamond wheel, then snap it on the score.
I have a bunch of old carbide end mills and a pp70. I'll try cutting one tomorrow. Let me know what size you need, and some closeup pics would be nice.

Hi hooda,
I can buy the Material ex China, Cheap enuff But the Import Duties Kills the Idea!
With the price of everything going up(fuel,wages,road tax etc.) Might just can the whole idea and close Shop!

Ps= How did you go cutting Tungsten with your Plasma?

PPs= Might Build a New Rig using Laser to Drill a hole 200mm Dia to at least 500m Depth

[JBnID]

Scotty-- What are you 'drilling'?
Trepanning or plunge milling or open die forging would be normal for those sized holes in steel. If it's a through hole in thick material, wire EDM is the way to go.
Hooda got it right. It's sintered tungsten carbide that is formed, not melted or forged. Sheets are available for certain bearings but it can't be cut with a plasma.
Normally, carbide tools are solid carbide or brazed carbide 'tipped' or inserts of carbide in tools forged and machined from high strength steel. Indexable tooling is the cheapest for big shops because it remains on size by simply changing the cutting corner or entire insert. Resharpened brazed tools are undersized as are solid carbide tools.
BUT, machines have to be designed and built for the milling stresses involved to get the benefit of carbide tooling. Old machines won't cut like new ones when using new tooling. Speed and volume is the king money maker and carbide is up to 250 times more efficient than HSS.

[Scotty1]

Scotty-- What are you 'drilling'?
Trepanning or plunge milling or open die forging would be normal for those sized holes in steel. If it's a through hole in thick material, wire EDM is the way to go.
Hooda got it right. It's sintered tungsten carbide that is formed, not melted or forged. Sheets are available for certain bearings but it can't be cut with a plasma.
Normally, carbide tools are solid carbide or brazed carbide 'tipped' or inserts of carbide in tools forged and machined from high strength steel. Indexable tooling is the cheapest for big shops because it remains on size by simply changing the cutting corner or entire insert. Resharpened brazed tools are undersized as are solid carbide tools.
BUT, machines have to be designed and built for the milling stresses involved to get the benefit of carbide tooling. Old machines won't cut like new ones when using new tooling. Speed and volume is the king money maker and carbide is up to 250 times more efficient than HSS.

G'Day JBnID Man o man i wish it was Steel! Be softer than some of the rocks i Drill thru.
I Am a Water Bore and Mineral Exploration Driller
I was Looking at Repairing some of the Drillbits That we use

But cutting the Tungsten is the Problem!