Print with Nylon
STYX-12 Nylon - In dept guide
I am somewhat of a “nylonholic”. Ever since I ventured into 3dprinting the endgame for me was printing large nylon objects successfully. The material properties, its strength while staying very light and flexible, its chemical resistance or its difficulty to print all made this material for me the ultimate goal. And so I printed a large volume of nylons. Very strong but very difficult to print blends, weaker but very printable blends and finally found the one that combines all the right material properties with printability.
Understanding of Nylon
What is nylon?
Nylon is the family name for a whole range of synthetic polymers hence there is no “generic” nylon. Each polymer manufacturer has their own blend due to the specific material properties they want their nylon(s) to have. Some value lightweight above tensile strength, some durability over shrinkage etc etc.
Understanding what your printed object will need to do is therefore key in determining which nylon you want to use. A future article will address how to read and understand datasheets. And when using nylon for 3Dprinters there is a whole other layer of parameters that apply, how does it extrude, layer adhesion, warping, etc, but also the hygroscopic properties (how much moisture can it absorb or loose when drying) are very important for successful prints.
How to treat STYX-12 nylon pre and post printing?
Moisture is your best friend and your worst enemy when it comes to nylon.
While printing you need have your STYX-12 nylon as dry as possible as the moisture in the filament will heat up quick in the nozzle and create bubbles which is known as foaming. Layer adhesion and surface finish will be visibly impacted and even buckling of the filament at the feeder due to the increased head-pressure is possible. We have designed the STYX-12 to be as low hygroscopic as possible (3.5% gravimetric) without affecting printing behaviour. Typically 3Dprinted nylons can absorb between 1% and 9% moisture (10.000 to 90.000PPM) Recommendations: Put the STYX-12 in a warm air circulating oven or in a filament dryer at 60c for 24 hours. That will (most of the times) get enough moisture out of the filament to make good and strong prints.
How did we get to those conclusions?
I have access to a 12k euro PPM (Parts Per Million) moisture analysis tool called the Aquatrac. This tool measures the exact moisture content of any filament we put into it. We started out with a simple vase print after we measured the PPM of the STYX-12. We measured 3722 PPM (which is 0,37%) and the resulting print was … well … not good. Bad layer adhesion and foaming on all layers. This is simply not what you’d expect from a nylon.
* to be honest, a vase is also not what you’d normally print with nylon but for this demonstration it displayed the issues perfectly.
Then we put the Nylon in a Printdry filament dryer for 24 hours and reprinted the vase. The moisture content was around 1200 PPM. The result was significant. The results can be improved even more by drying it more, but if you dry the nylon too long you can and will ruin its printing capability. Recommendation: Dry the STYX-12 no longer than 48 hours @60c in the oven or filament dryers such as Printdry or you will ruin its printing capability.
Here is an example on how nylons hygroscopic data compare to other generic filaments.
But once we have printed the object, the tables turn. The best thing you can do after printing is to put the object into a bucket of water as the maximum material properties are achieved when the finished nylon print is as wet as possible. This is why at injection moulding factories the finished objects are immersed for a period of time into warm water. Recommendations: leave the printed object submerged in a bucket of water at room temperature for a few hours or preferably overnight and you will have the toughest object achievable.
How to deal with moisture in Nylon prints?
Like we said, all nylons are hygroscopic which means they like to absorb but also release moisture. There is a direct relation to time as the following image shows.
As is clearly visible here, moisture release is high in the first few hours and then levels off. This is also why getting a perfect dry nylon is almost not possible or even wanted as too dry of a nylon will not print easy.
Almost the same curve is applicable for moisture absorption. High absorption in the first 24 to 48 hours and then levels off as the filament saturates.
So keep that in mind when you do a nylon print. A soon as you take the spool out of the vacuum bag it starts to absorb moisture which can affect your prints. Filament dryers are designed exactly to combat this behaviour by drying the filament inside the housing and only exposing the filament to the environment moisture for the minimal amount of time possible when it enters the printer.
Printing result of a nylon engine