3D printers provide a number of advantages over traditional manufacturing prototypes for small production runs or low volume end-use parts. Prototyping is empowered by repeatability, accelerated speed to market, and low-cost product testing. Dimensional and chemical stability of engineered thermoplastics in combination with advanced additive manufacturing technologies provide design freedom for geometries that were once unfeasibly complex. The power of 3D printed prototypes resides in the ability to construct, print, assemble, hold, feel, and check for fit and function before spending tens of thousands on casts or injection molds. Proprietary designs stay in-house, trade secrets avoid spoil, and design teams receive immediate feedback loops on critical functions. Importantly, designs that were born to fail, fail first, and fail fast, before unforeseen design constraints send projects to the scrap yard after months of time and millions of dollars dumped into R&D. The success of 3D printing prototypes is dependent on its fit, function, and aesthetic in a way that mimics an initial design with precision. Diagnosing the cause and precursors of 3D printed part failure is complex. Stringy prints, jams, bubbly uneven surface textures, improper extrusion flow, soft or brittle parts, and other common 3D printing build defects all inspire the same question…
“Why Do My 3D Prints Keep Failing?”
3D Printed Part Failure Goes Beyond the Printer
Part orientation, minimum thickness, geometry restrictions, support structure, material properties: When it comes to achieving the most functional 3D printed parts, you’ve thought of it all. Inadequate air flow, differential cooling, material constraints, and non-uniform thermal gradients: they all contribute to the common ailments like heat distortion, extrusion failure, and part curling during 3D printing. But what about part failure contributions that extend beyond the chamber or print tray? Storage environments and post processing techniques also contribute heavily to the final quality of 3D printed parts.
The Impact of Moisture on 3D Printed Parts
Mass flow rate is directly correlated with the moisture content of 3D printed filament. Higher moisture content yields the lowest viscosity and the highest mass flow rate. While high flow rates are generally desirable, an unregulated flow rate leads to over extrusion.
Because some 3D printing filaments are hygroscopic, meaning that they absorb moisture from the air, prolonged exposure to even moderately humid room air causes moisture saturation. After 150 hours in standard conditions, PLA filament may swell up to 40 micrometers before reaching its saturation point. 3D printers rely on tight tolerances and extremely small layer heights. Before the print even gets underway, an increased filament diameter of even 20 – 40 microns, (roughly the width of a human hair) can derail a build before it ever begins.
3D Printing Filaments That Should Never Be Stored In Ambient Air
Nylon, polycarbonate, and copolyester filaments all suffer ailments when exposed to moisture for extended periods of time.
PLA is an organic material that readily absorbs moisture, and is extremely sensitive to trace water content. Moisture also affects the diameter of the filament when it in storage.
Because PVA is a soluble support material, its ability to absorb water is a fundamental characteristic. Even mild humidity is enough to ruin an entire spool of unsealed filament.
The effect of moisture on nylon 3D printing filament is profound, as it may fully saturate in as little as 18 hours. *READ: Important note about Nylon*
Indications of Possible Moisture Content in Failed 3D Printing Builds
- Filament cracks or makes popping noise as the filament is pushed through the extruded
- Holes in the top of parts
- Extruder tip bubbles with a tiny burst of steam, stringy or drooly
- The filament will not adhere to the print bed
- Repeated builds seem inconsistent or fail no changes in variables
- Extruder motor stops but filament keeps coming out
- Extruder motor starts but filament extrusion is delayed
- Parts become soft, fragile, and break easily
- Extruder jams
What’s Wrong with Drying 3D Printer Filament by Baking It
While heat drying 3D printer filament in an oven is overwhelmingly accepted within the 3D printing community, time is a major consideration. PLA and Nylon filaments may take upwards of 4 – 8 hours to dry between 150°F and 200°F. The process is inefficient, and applying heat to thermoplastics with no ventilation is a questionable risk. Ultra fine particles (UFPs) and volatile organic particles (VOCs) infamous within chemicals like ABS during extrusion don’t account for residual substrates leftover from the manufacturing process, which could be activated during baking.
Problems with Dry Baking 3D Printing Filament
- Natural gas and propane fired ovens produce water vapor, therefore an electric resistance oven is required.
- Heating entire spools of filament is not recommended or advised, hence unspooling and respooling is required
- Unused filament will require rebaking if again exposed to ambient air
- Heat relaxes the stress in the filament, causing it to relax in the coiled state
- Overbaking can cause the filament to melt and stick to itself
Improving the Quality and Finish of 3D Printed Parts?
The thermoplastic filament used to print additively manufactured parts requires attentive storage, handling, and processing. Filament and support material storage with minimal heat and the least amount air exposure is always ideal.
Advantages of 3D Printer Filament Cabinets
3D printing filament cabinets are the better, if not best moisture control solution for filament storage. Temperature controlled drying preserves material stability, tensile strength and prevents 3D printed parts from warping or deforming on the print bed. An automatic humidity control cabinet with a hygrometer provides a quick and simple way to store 3D printer filament without hassle or baking. Changes in humidity directly affect air temperature, therefore automatically controlled drying environments exceed nearly all other methods for drying and storing 3D printing filament. Your filament will stay completely dry, easily accessible, perfectly identifiable, and ready to be used anytime you need them for a print. Simply set the desired humidity level, store the filaments and the dehumidifier will take care of the rest.
For most DIY enthusiasts the cost and risk associated with flaws in final prints is small, as the final application and end-use is generally limited to trinkets and experiments with minimal consequence. For commercial applications that require large quantities of filaments spools and project turnover on tight deadlines, temperature and humidity controlled storage is a cost-effective option that eliminates variables and volatility. If a 3D printing filament storage prevents one failed build of 80+ hours with expensive engineering grade thermoplastics, at only $350, an automatic 3D printing dry cabinet has already paid for itself.