Printable Carbide Opens Up Interesting Possibilities

Sandvik, a large company headquartered in Sweden, has apparently been producing cemented carbide for a long time — according to them, since 1932. The material is known for being highly wear-resistant. Now the company says they have a process to 3D print the material. You can see a video about the new material, below.

If you haven’t encountered this material, it is essentially fine carbide particles bound in metal. You’ll find the material widely used in cutting tools. The slogan “Freedom of Design has Never Been Harder” is both clever and confusing, but we took their point.

The process is more or less like other metal binder technology. A powder of tungsten carbide and cobalt mixed with glue creates a green body which you still need to fire to get to the finished part.

What kind of things can you make? Here’s a quote from one of Sandvik’s engineers:

For instance, in wire drawing, productivity is usually limited by how fast the wire can be drawn with maintained quality, which in turn depends on the temperature in the wire drawing die. People have been trying to solve this problem for decades, but it’s been extremely difficult. A 3D printed, cooled wire nib is the answer to this riddle. It took a mere four days to produce, from the first basic sketch to the fully sintered product – thanks to our materials and proprietary process.

Don’t plan on loading up your Ender 3 with cemented carbide filament. This is, after all, a metal material. However, 3D printing can offer geometries that would be difficult to obtain with traditional methods. So even if you have to turn to a professional 3D printing shop, it is good to know you can create in this ultra-hard material.

Printing in metal has a different set of issues than using plastics. If you really want your current printer to do metal, it can, but you’ll have to cheat a bit. Or try electroplating.

23 thoughts on “Printable Carbide Opens Up Interesting Possibilities

  1. I used to be a carbide machinist. It’s probably the most hazardous machining healthwise outside uranium machining at Los Alamos. Many who do it get heavy metals poisoning and die young. There is no amount of money anyone could pay me to do it again, but I will try walking you through the process of how it is traditionally created.

    Green carbide is how unsintered carbide material is referred to, it looks and feels exactly like heavy pencil lead. Similar to graphite blocks, except darker and extremely heavy. You can cut it the same way- it falls away in a heavy powder. I used to help make the stuff from scratch, and mixed powders by weight of different metals to be pressed in huge hydraulic presses.

    It starts as a 30 gallon drum is filled with exact ratios of various metal powders, mostly Tungsten & cobalt powder, and depending on the use case (there are versions with higher wear resistance, and various other properties) other materials get mixed in by weight. Tantalum carbide and chromium were a couple I can remember. It’s then blended together with a non-sparking metal blending machine for homogeny.

    Everything in a carbide plant and machine shop is generally designed to be non-sparking because the material is actually flammable in the green state. I have seen it catch fire several times and I can’t even describe how bad the smell is. Class D fire extinguishers have trouble putting it out completely because it smolders under the powder and it glows nuclear green yellow like something from The Simpsons opening- a carbide fire is a scary thing if it’s not controlled quickly, so usually it was isolated to a barrel on wheels and wheeled outside to burn itself out.

    The powder has no glue added to it- only pure Heptane. Heptane is the ultimate tool cleaner. It’s one step away from octane- the stuff they rate in gasoline. It’s a colorless liquid that looks exactly like water but has a slight sickly sweet smell and it’s more flammable and explosive than I can ever convey. There are vats of hundreds of gallons of heptane used in carbide production, heptane is used in mixing the powder together before it is put in a special vulcanized rubber sack that goes into an isometric press- it uses compressed liquid as a medium to smash the sealed bag into as dense a block of material as possible- enough that it stays solid once they take it out of the press.

    Once it’s out of the press, it’s either a round or rectangular billet, the ends look exactly like sausage where the bags compress on the material and they slice those off and reuse them in the next batch. You know have a solid Billet of green carbide that you can slice up on a diamond band saw and then machine traditionally. We typically use carbide tooling for this it cuts its own kind just fine when it is not sintered- but many tools use polycrystalline diamond wafers for cutting edges for wear resistance. It can also be ground to shapes too, it responds again almost exactly like graphite.

    As far as I know there is no actual glue used in carbide production the cobalt metal acts as the binder, especially after it has been sintered. Sintering shrinks the material but every batch of material is slightly different- so each batch of material is tested against a complex equation that determines shrink factor isometrically for that batch. Once that is known parts are made accounting for that shrink factor to a isometrically larger size, so that when machining is done and they are sent to be sintered in a large oven they come out almost completely finished to size.

    As you can guess many pure metal powders are very expensive so waste is tightly controlled and kept to a bare minimum this way and because grinding is pretty much the only thing involved after the material is sintered (red carbide it’s called in the shop, just to differentiate it, but it’s what your cutting tools and router bits are often made out of) only diamond tooling can really grind the stuff so further grindwork is very expensive. Diamond grinding wheels are used exclusively in the green state as well for wear resistance.

    Anyway, thats the process.

    I’m not sure how Sandvik is able to achieve the material holding form when 3D printing it- without isostatic pressure creating a billet of it, they have to be using some kind of actual binder material to be holding it together at a micro scale level. I wouldn’t be surprised if they are actually using some sort of actual glue in their process or something acting with that effect because you can’t simply press the material together under normal pressures that a standard 3D printer could do to keep the material solid. And they are going to have the same issue the stuff made with traditional manufacturing has and that most metal 3D printers have- calculations for shrink factor on sintering.

    Judging from what I have seen from examining 3D metal printers in person at trade shows and talking with representatives, I’m guessing the actual binder for the premixed carbide powder is likely some form of special wax.

    I hope they have diamond printing orifices- or that stuff is going to very quickly wear out their print nozzle!

    Hope this information was interesting and useful to someone.

      1. Now that’s one of the nicest compliments I’ve ever received.

        I’ve commented on here since a couple years after the beginning of the site, a long time ago, usually under just the name Drew. Someone else took that at some point so I started using this moniker. The people who’ve been here for a long time probably recognize my writing at this point though I don’t comment as often. I’m just one of those people that’s out there who loves the place.

        I have nothing but respect for the people who have made this site so amazing and I have no idea how they do it and have time to live their lives unless it is a full-time job. I actually work as a prototype machinist and I have almost zero free time what little I do I spend here and a few other places.

        I’m really happy you enjoyed my long-winded response I’m happy other people seem to too. If you know anyone in carbide machining- please- convince them to get out of it. I wasn’t joking when I said co-workers died of heavy metal poisoning. It’s an amazingly toxic business and while everyone should be wearing a respirator in the shop if you’ve ever toured one you realize how impractical that is and practically speaking everyone is breathing that dust all day.

    1. @Drew
      Glad you made it out with both your lungs, as most carbide dust is usually tumorigenic. It is actually possible to make SiC parts smaller than 2” in a microwave furnace, but anything larger cracks up from internal stresses as the decades old NASA paper details. Something like Tetrabor however, is pretty much the worst material on the planet to handle.

      There are a lot nicer Zirconia or Alumina industrial processes around like the new metal-paste machine.

      1. I’m still convinced I’m going to die at a younger age from what I experienced in that job. It did introduce me to PCD tooling, ballscrew replacement, live tooling lathes and a lot else, so it wasn’t a complete waste. I left to go to watchmaking school, and never looked back.

        The area I live near, Pittsburgh PA, has a high concentration of carbide shops, in nearby Greensburg.

        1. You, I’ve ground a few custom step drill bits at previous job (using surface grinder and spindex). Wore a respirator and plastic coveralls, cleaned up the room best I could.

          One of the worst comments I’ve seen on Hackaday was someone bragging on using an angle grinder to make a carbide guitar bridge from some scrap (took him all day!). I pointed him to the MSDS. Yikes.

          Worst part of carbide dust is the Cobalt, IIRC about 2% of people are highly reactive and will just die off in agony after very small exposures.

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