Tungsten material

[Martin CargillParticipant @martincargill50290]

One of the jobs I do is to look after a stapeling machine. It is a hand held staple gun that has been modified to fit into a small machine to fire staples through a piece of light aluminium extrusion.  The staples are turned outwards by an anvil under the extrusion, in a similar way to the second anvil on a paper stapler.

The problem that I have is that the anvils wear out (they are grooved by the staples). I have made some new ones but they wear too fast, they were made from 8×8 mm tool steel intended for lathe turning.

I have just been in contact with an old colleague who recollects that the original anvils were made from tungsten (that was heat treated after being machined).

Does anyone have:

a) Any idea where I can find this type of material?

b) Any idea as to how to heat treat this material.

c) If it turns out that I can’t make these, who could?

 

Thank you for your time

 

Martin

[HOWARDTParticipant @howardt]

I used to design special purpose machines, long time ago, we used to use steel from Carrs Tool Steel Ltd.  If you ring them and tell them what you are using the material for they will make suggestions on what they can supply with all the heat treatment.  One of the jobs I had was to roll finish a inside radius on a steel part, the initial test tool supplied to the end user lasted about twenty parts which was good enough to prove concept, the final tool using steel recommended by Carrs did over a thousand parts.  So well worth a try.

[Clive Brown 1Participant @clivebrown1]

I wonder if your friend was actually refering to tungsten carbide. Common for cutting tools due to its extreme hardness. It’s usually formed by powder metallurgy processes. Can’t really help with your questions though.

[peak4Participant @peak4]

Could you adapt something off-the-shelf, e.g. No.21?

https://kihlberg.com/en-gb/tools-en-gb/packaging-en-gb/120370/#spareparts

Bill

[Martin Cargill]

On 5 June 2024 at 15:53 Martin Cargill Said:

[…]

I have just been in contact with an old colleague who recollects that the original anvils were made from tungsten (that was heat treated after being machined).

Does anyone have:

a) Any idea where I can find this type of material?

[…]

Answering just that one question with some confidence, Martin

Search ebay, or other sources, for “bucking block”

[no, that’s not a polite gentrification … it’s the proper name]

MichaelG.

[SillyOldDufferModerator @sillyoldduffer]

Tungsten is available from China through ebay, but I think Martin’s colleague has half remembered, and the material is Tungsten Steel.  A likely candidate is T15, which is the hardest of the HSS family.  Couldn’t find anyone selling it in the UK, but littlemachineshop stock it.

Tungsten and T15 are both extremely difficult to machine, so think grinding.  Tungsten can’t be heat-treated, and HSS is notoriously difficult, requiring sequences of precision time and temperature heat soaks.

Sounds like Martin was on the right track with 8x8mm lathe turning tool-steel, but the job needs a ‘super’ HSS.

Dave

[Michael GilliganParticipant @michaelgilligan61133]

Just for info. [as I have no personal experience of this, and have not read the full paper]:

https://www.scientific.net/SSP.118.35#:~:text=By%20applying%20the%20cyclic%20heat,from%20round%20to%20undulated%20shape.

MichaelG.

[Anonymous]

As stated above tungsten carbide is not homogeneous but consists of finely powdered tungsten carbide mixed with a binder, usually cobalt. The material is pressed and sintered to near final shape and then ground.

The same applies to ‘pure’ tungsten metal, it is a mix of tungsten powder and a binder. The material can be turned with carbide inserts and drilled with carbide drills. However, the material is very brittle. This is what happened when I tried to tap it:

Normally ‘tungsten’ metal is an alloy with a few percent of other materials, often iron and nickel. These alloys are less brittle. Machining and drilling with carbide tooling is fairly straightforward. This is a cylinder turned and drilled 8mm deep with a 1.2mm carbide drill:

The final application was a governor ball consisting of two hemispheres screwed together:

While machining tungsten alloy is fine, tapping proved to be a nightmare. The alloys have a high tensile strength and close up on tap, locking it solid. I broke several taps, including ring taps specifically for high tensile materials, before discovering that my worn set of M4 Dormer hand taps worked best.

Tungsten alloys are available here:

https://www.smithmetal.com/tungsten-alloys.htm

But sit down and do up the seatbelt before asking the price. A good few years ago I asked Smith Metals for a price on a 10″ length of 7/8″ diameter tungsten alloy. Answer was around £600.

Andrew

[ChrisLHParticipant @chrislh]

I was involved in a project years ago which demanded use of a hard, wear resistant material. We specified “Ferro-Tic” because it could be machined in the soft state and subsequently hardened by heat treatment. The project was cancelled before the components were made so I cannot say how well it stood up to its job. It’s still available according to my internet search so somebody must have found it useful.

[DiogenesParticipant @diogenes]

If one used older flat inserts, something like this;

https://www.ebay.co.uk/itm/335373616071

..could the ‘forming groove’ be ground or EDM’d into them..?

 

PS. interesting contribution, Andrew Johnston..👍

[Robert Atkinson 2Participant @robertatkinson2]

Not my area of expertise, but it sounds to me like you need a alloy designed for tool and die applications i.e tough and wear resistant. I applied google. This:
https://keymetals.com/tool_steel_guide.html
suggests O1 or D2.
O1 contains tungsten and has a lower heat treatment temperature than D2.

Robert.

[Michael GilliganParticipant @michaelgilligan61133]

Andrew

That ‘breakout’ of your tap is very interesting, and I’m sure it surprised and distressed you !

Without wishing to imply anything more than a morphological similarity, it looks like the Tungsten Alloy behaves rather like cast iron, but on a smaller scale.

It is good in compression, resistant to impact, and ‘tough’ [hence the use for bucking blocks] … but, we now see, fails in tension.

Every day is a SchoolDay … Thanks.

MichaelG.

.

Edit: __ A rather good paper about the small-scale structure of Tungsten Alloy wire:

https://www.researchgate.net/publication/370703150_Research_Status_of_Manufacturing_Technology_of_Tungsten_Alloy_Wire

 

[Michael GilliganParticipant @michaelgilligan61133]

Robert

Thanks for the link to KeyMetals

… a very useful reference.

MichaelG.

[duncan webster 1Participant @duncanwebster1]

According to https://www.coventry-grinders.co.uk/product/imperial-gauge-plate/#:~:text=Gauge%20plate%20is%20made%20from,of%2062%20degrees%20Rockwell%20C.

O1 is what we used to call gauge plate

 

[duncan webster 1]

On duncan webster 1 Said:

According to https://www.coventry-grinders.co.uk/product/imperial-gauge-plate/#:~:text=Gauge%20plate%20is%20made%20from,of%2062%20degrees%20Rockwell%20C.

O1 is what we used to call gauge plate

 

It’s all relative!  Martin’s stapling machine wears out tool-steel anvils, suggesting the requirement is extreme.  Nothing wrong with O1 for many applications, but it’s ‘an excellent general purpose tool steel often used where the expense of a high carbon high chromium tool steel would not be justified‘.  I fear from Martin’s description that the expense of better than O1 / Gauge Plate may be justified.

An alternative might be to make many anvils from O1 and treat them as consumables, replacing them frequently as need be.

The shape of the anvil might be important too.  Angling the sides to progressively bend the staples might considerably reduce the impact force on the the anvil compared with a more direct strike.

Dave

[Michael Gilligan]

On Michael Gilligan Said:

Andrew

That ‘breakout’ of your tap is very interesting, and I’m sure it surprised and distressed you !

On the contrary I wasn’t surprised as material datasheets had warned that the material is brittle. Only the material broke, not the tap.

I was annoyed when, in a later experiment, I broke a new ring tap.

Andrew

[Michael GilliganParticipant @michaelgilligan61133]

I stand corrected, Andrew

… not for the first time.

MichaelG.

[mike robinson 2Participant @mikerobinson2]

Try this company, they were very helpful

They produce carbide blanks for cutters etc

Matt or Mark

Hartmetall UK
Tel: +44 1299 253882

[Martin CargillParticipant @martincargill50290]

Thank you everyone for taking the time to reply.

I have ordered some tungsten material to try to make some new anvils.

Today I tried putting one of the old, worn (tungsten?) anvils into my surface grinder (thought I had better check that I can make parts using the material I have ordered). I was surprised to find that I could grind the existing old anvil with ease, and I only had to remove .005″ to grind out the groove that the staples make during use.

Therefore it seems that I have a temporary solution as I can refit the old anvil, until I can try some of the new material in the machine.

I expect that the current anvil (made from tool steel) will start to fail within the next10-14 days so I’ll provide an update after that.

 

Thanks again

 

Martin

 

 

[David George 1Participant @davidgeorge1]

Wy dont you use tungsten carbide. I have used it for many special machine jigs and tooling. You can braze a piece on to a arbour or back plate or use a solid piece inserted into an adjustable screw etc.  They were used to hold parts for further machining or inspection before further machining.

David

[old martParticipant @oldmart]

Tungsten in a machinable form such as Densimet would not be anything like as hard as HSS and tungsten carbide which is hard, is made by sintering, when the finished shape is moulded and is not heat treatable. Tungsten carbide could be machined with principally diamond tooling but might be too brittle for stapling but would never wear out if it could be used.

I have a supply of Densimet tungsten at the museum and it can be machined easily with carbide inserts, solid carbide endmills and also drilled and tapped with HSS. It maked really good holders for carbide inserts being dense and stiffer than steel. Our particular grade is not brittle. Here is a photo of a boring tool I made for milling, the screw threads are 2mm.

 

 

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