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.
3D printers allow a designer to assemble, hold, feel, and check a part for fit and function before spending tens of thousands on casts or injection molds. Avoiding contract manufacturers means designs stay in-house, trade secrets avoid spoil, and product teams receive immediate feedback 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.
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
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
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