We Are Learning 3D Printing Through Our Personal Experience…
NinjaFlex is the name of a thermoplastic elastomer (TPE) filament for 3D printers developed by a company called Fenner Drives. This is not the first flexible 3D printer filament that we are checking out, but it is probably one of the most popular one for this type of filament. The NinjaFlex filament is designed to print on a wide range of 3D printers that use direct-drive extruders with settings similar to the ones you would use for normal prints using ABS or PLA material. There are some differences though that you should be aware of regarding the use of flexible filaments and more specifically NinjaFlex.
This filament does not require you to have a heated build plate, it should stick well to the standard build plate of 3D printers designed only for PLA printing and it should stick well to most surfaces. The manufacturer recommended extruder temperature is between 210-225°C and what you need to make sure to do is to lower the extrusion speed to about 1/3 of the normal one for your 3D printer or to about 30 mm/s in order to have best results. This is similar to other flexible filaments such as the Arnitel Eco Flexible filament that we have already tried. Arnitel is producing flexible filaments with a sightly higher hardness of Shore D between 40 and 70 and the NinjaFlex is rated Shore A hardness of 85, making the NinjaFlex filament slightly more flexible than the Arnitel 40A that we have tried.
The recommended maximum temperature for exposing the NinjaFlex printed parts is 66°C, going higher than that they can start to feel softer not because they are flexible, so the thermal stability is similar to the one that PLA filaments have. The recommended minimum temperature for NinjaFlex printed parts is -30°C, because going below this temperature will make printed parts increasingly brittle and they may even shatter. Also you should note that while occasional contact with water will have no adverse effect on NinjaFlex, the product will degrade and lose its elastic properties when submerged in water for extended periods of time.
The NinjaFlex flexible filament is available in multiple colors including: Black, White, Blue, Red, Silver, Gold, Orange, Green, Semi-transparent, Yellow and Pink in 1.75mm 0.50 kg spools as well as 3mm 0.75kg spools. We got a Green Grass filament spool with diameter of 1.75mm for trying the filament out on our MakerBot Replicator 2 3D printer. Printing with our regular settings for PLA with an extrusion speed of 30 mm/s at three different temperatures has produced varying results. The recommended temperature range by the manufacturer is 210-225°C and we have tested printing at 210, 220 and 230 degrees Celsius with the results as seen on the photo above. At 210 degrees Celsius our test simple house was not not perfect, the base was fine, but the roof had some glitches making the printed part looking ugly, though the filament had no trouble sticking to the build plate. At 220°C visually the result was the best, great looking and smoother finish at 0.2mm layer height at Standard print quality. Going a bit higher and out of the recommended by the manufacturer temperature range still gives us a good print, but the surface finish looks a bit rougher when reflecting light. So it seems that you might want to stick to the upper recommended temperature range when printing with NinjaFlex flexible filament such as 220-225 degrees Celsius for best results.