Is carbon killing your nozzle?
TL;DR: Yes, carbon filled filaments will cause rapid and significant damage to standard nozzles. Don’t fear however! We’ve developed a new, incredibly wear-resistant nozzle that basically eliminates wear, and they’re available in a range of popular sizes for both E3D-v6 and Volcano nozzles. Get them here.
If you’re interested in the gory technical details and want to see some really cool microscope analysis of nozzle wear then read on!
New filaments, with weird and wonderful fillers, appear all the time. We wanted to investigate what impact these materials have on our hotends.
More and more companies are now selling materials with short chopped carbon fibre or glass mixed with a resin. Materials like ColorFabb XT-CF20 and Proto-Pasta Carbon Fibre PLA, along with many others, are making a splash on the market due to their large boosts in stiffness. Many other filled materials exist (ColorFabb BronzeFill, ProtoPasta Stainless Steel PLA): all these metal-filled materials will cause nozzle wear too.
Almost all filament manufacturers give a vague warning about carbon fiber or other filled filaments causing “additional wear” on the nozzle of your printer. What does this mean? Is printing carbon going to destroy your printer? How quickly? What can be done? We decided to do some in-depth testing to see if there was an issue and, if so, try and come up with a solution.
To get a handle on wear rates we ran some controlled tests with our standard nozzles.
We took a brand new brass 0.40mm nozzle, fitted it to our machine, and printed 250g of ColorFabb XT-CF20. We then took that nozzle and cut it in half, and inspected it under the microscope.
What we saw was pretty surprising:
The tip of the nozzle has worn significantly, being worn down making the nozzle shorter in overall length. The tip of the nozzle has also been rounded over into a dome shape due to abrasion. Most surprising was the level of wear on the inside of the nozzle orifice which has been significantly opened up in diameter and has worn in an ugly uneven fashion.
The wear on the inside of the nozzle orifice causes the nozzle to taper out in diameter. Furthermore, for some inexplicable reason the wear is greatest in the middle, causing an ovoid type wear cavity in the nozzle orifice.
As a control we took the nozzle that was previously on the machine, which had printed many many kilos of standard materials with no abrasive fillers over the course of a few months, and cross sectioned it for the microscope too.
There was no observable wear at all on the nozzle that had printed only standard materials.
Just to be sure, we sacrificed another nozzle at the altar of carbon and ran the same test again; 250g XT-CF20, standard brass 0.40mm nozzle.
For this nozzle we took some particularly nasty solvents and cleaned away any residue of the carbon filled resin. You can clearly see that the wear caused is not a nice even polishing, but a really nasty gouging, resulting in deep sharp ridges and grooves inside the orifice. The wear pattern was pretty much identical to the prior test, confirming our results.
Clearly, after only 250g of carbon fibre the nozzle has been significantly degraded: I would consider this nozzle wrecked. Although it will still print this is going to result in unpredictable erratic printing results. 250g is really not a lot of material, around 1/3rd of a spool, and although nozzles are cheap (£4.50) compared to the material itself (£38), having to install a new nozzle 3 times over for a single spool isn’t a proper solution.
So if we want to print carbon we really need something more wear resistant, a lot more wear resistant. We introduced stainless steel nozzles some time ago, before the introduction of carbon filled materials. However these weren’t designed for wear resistance, they were for applications such as food and medical where the use of brass, which has a minute lead content, is unacceptable. Stainless does fare better than brass, wearing at around 30% the rate of brass nozzles, but eventually after a single spool of material you end up with a nozzle that has sustained the same damage levels.
We took our standard nozzle design, and applied some material science. By changing from brass to a carefully selected steel, and then post-processing that steel nozzle with a combination of thermal and chemical treatments we can create an extremely hard and wear resistant nozzle.
The results are striking, and pretty self explanatory. Even more so because the hardened steel nozzle to the right has printed 2.5kg of various carbon filled materials, and glass filled materials too. Ten times the amount of material (250g) that the brass nozzle on the left has printed.
The nozzle was so hard it was extremely difficult to cut in half for a cross section view under the microscope! We had to resort to abrasive grinding to take off one side of the nozzle to see inside.
Looking at the two head on now, you can see how the hardened nozzle has completely retained it’s original shape with zero observable wear (the slight radiusing around the circumference of the tip flat is intentional and created when the nozzle is machined). The brass nozzle orifice is larger, and no longer round or even. The length of the nozzle has been worn down, and the definition of the tip flat has been completely erased, worn into a rough dome on the end of the nozzle.
In all our observation and testing, despite really trying to cause wear with every weird and nasty filament in our filament arsenal (which is extensive), the nozzle appears to be experiencing zero observable wear.
We’re introducing these nozzles as a new product immediately. We’re producing them in a range of popular sizes for both standard E3D-v6 HotEnds, as well as E3D-Volcano nozzles. Production is a complex process, involving machining and extensive post-processing. This means we have somewhat limited stock at present, but we’re refining our process and increasing capacity.
Because of the thermal and chemical treatment applied to the nozzle they do have a bit of a dark, sometimes uneven looking coloration and surface finish, and there can be a small amount of residue on the nozzles despite our final cleaning process. The coloration variance is normal and doesn’t affect function, any residue left on the nozzle will quickly be flushed in the first few millimetres of extrusion, especially if you flush it out with an abrasive filled material!
Paying a little extra for a hardened, wear-resistant nozzle makes both practical and economic sense. By the time you’ve printed a single spool of abrasive filament you’re saving money. It also saves a lot of time as you won’t be constantly replacing worn out nozzles. Furthermore you’ll be future-proofed for upcoming materials, we think these nozzles should be able to handle just about anything the material manufacturers think of next.