The Drying Solutions
Nylon (PA 6) is a difficult filament for FFF printing. It's a useful engineering plastic due to its toughness, but its love of absorbing moisture out of the air is legendary. One of the major struggles faced by 3D printer owners is keeping filaments dry once the bag is opened. (Oh and because these are vacuum sealed, the slightest p[inhole lets in air - and the humidity it contains. In fact, because of possible air ingress at the time pf packing, your PA6 nylon filament may arrive already having absorbed moisture.)
The problem with hygroscopic - aka 'water-absorbing' - engineering plastics for printing is that the water starts to boil out of the plastics as it leaves the print nozzle and the expanding water / steam blows little holes in the model, or excess stringing occurs, or even a collapse of the model.
Other Plastic Operations
Filament printing is just one operation we can perform on plastics that depends on dry - really dry - plastic material. In an injection molding die, steam and water in the plastic can leave voids, blow out through steam pressure, and generally ends in failure.
If you're pressing plastic into plate form, the water will leave all manner of deformities and imperfections in the plate. (And that's even true of the sandwich press plaste BTW. Hard experience talking here.) In fact, moisture absorption by plastics during manufacture is a Bad Thing.
(The exception (which is actually not an exception as it occurs AFTER the manufacturing processes) is that strimmer and weed trimmer lines made of nylon should be allowed to absorb moisture to make it more resistant to fracturing in use.)
Are There Solutions?
Thankfully, there are solutions for FFF processes in particular, and some general advice for other processes. Here's a short article detailing some solutions.
Your TL;DR is that there are different processes depending on your needs. There are solutions for drying out filament that's become waterlogged, and involve taking a spool of filament to a temperature below the melting point of the filament (AND the melting point of the spools the filament is on! Also true story) but as high as possible to evaporate off the water.
There's a solution for keeping dry filament dry in cabinets, and in smaller dry keepers that feed directly into your printer. No one solution seems able to do all of it. (The article is advertising for a claimed all-in-one solution but you also need to keep sane costs in mind - especially like myself, on a pension.)
Some Home Grown Solutions
TL:The credenza, with door closed. TR:The filament section open.
LL: The back of the dehumidifier LR: Overview of the printer cabinet
The good news is that for the lower temperature rated plastics there are a few inexpensive solutions.
Many people convert an inexpensive circular food dehydrator with thermostat into a filament dryer. These barely manage to reach 60C and generally run even cooler than that, but they CAN dry filaments slowly IF you also keep some fresh silica gel in it where it can absorb the moisture as it's released, and change it frequently.
Silica gel is also good in any air sealed tub you want to keep your filament in once it's dried, but it has a definite use life and once it's absorbed water you either throw it out, or waste even more energy drying it out for (one or two cycles of) re-use.
I wanted to store 10 - 25 spools of filament (mainly PLA and some PETG) so I made a solution with an old desk credenza thing (one shallow drawer and one file drawer) that I actually also mounted the printer cabinet atop, and it's adequate for most things.
The way it keeps things from moisture is that it has a small electric dehumidifier inside, the kind that distills the humidity out of the air and fills a water drawer. Because it runs with about 45W it also keeps the inside of the cabinet at 25C - 35C and below 32% RH, and there's ALSO a tub of silica gel in there that gets changed when it looks like it's absorbed enough.
I just took all the drawers out and turned the fronts into a hinged door, sealed it, and made a shelf for the dehumidifier.
(Messy) top of cabinet with filament entry, and the sophisticated
There's still a shelf to go in the Fillie Stash but so far it's kept a decent temperature and humidity for over a year now and only added about 6-8 dollars to the electric bill for the year. It probably won't be useful for nylon (PA 6) and other engineering plastics but it's kept the PLA and PETG fairly stable. There's usually a small tub of dessicant in there as well, I've changed that twice in over a year, so they last 6-8mths if you don't leave the door open all the time.
Not shown in the pictures is an IKEA Förnuftig air purifier with the additional charcoal filter to absorb plastic fumes, it's generally run at lowest speed to clear the air of passing particles such as, you know, COVID if we have unvetted visitors, and dust from the road outside. When I'm working it gets cranked up to 3 and pulls fumes out of the air. (Activated charcoal filtering works wonders against the volatile organic compound fumes from plastic and you really should consider one of two purifiers especially in view of the still very much a pandemic level of COVID.)
And that's it for this article. Hope it inspires you to make a DIY solution for your filament storage.
Footer
Please - take a look at my News Stand where you'll see live updated links to everything I publish; or take a subscription to my weekly newsletter where you'll receive the same information in your inbox for free; Or contact me via the webform or directly email me if you'd like to help; or donate either directly or at my Ko-Fi page for the price of a coffee, or even make a regular monthly donation there.. It all helps me to build projects like this one, keep the servers and domain names paid for, and lets me take subscriptions for research.
No comments:
Post a Comment