Durable and ultra flexible, NinjaFlex is one of the newest 3D printing materials on the market today and it has already proven itself to be extremely versatile. With virtually the same printability of ABS and PLA but considerably more flexiblity, NinjaFlex is taking 3D printing places that it has never been before.
By a wide margin, the most popular 3D printing materials are ABS and PLA, and while the two materials are chemically very different, both thermoplastics are pretty similar in consistency, look and in final print quality. Acrylonitrile butadiene styrene — or ABS — is what they make Lego bricks out of and it is made from petroleum or natural gas products. So not only is ABS non-biodegradable it will smell pretty badly of chemicals while printing. Polylactic acid, commonly known as PLA, is a plant based material that is considered by many to be friendlier to the environment. While that is only true if the environment likes non-biodegradable plastics made from previously biodegradable plants, like ABS it is at the very least recyclable. Both materials are popular because they can be extruded into just about every 3D printer on the market and most importantly, they are relatively inexpensive. But there are drawbacks to both materials. The rigid, unforgiving final prints can often be fragile, especially if they are cooled too quickly during printing. And if you need to print something with a rubbery texture more flexible than ABS or PLA, then you’re out of luck if you only have a typical home or desktop 3D printer. That material gap left a hole just big enough for NinjaFlex to squeeze through.
NinjaFlex manufacturer, Fenner Drives, labels it as a Thermoplastic Elastomer and it resulted from the experiments of several engineers who were looking for an FDM filament that could be used to rapid prototype highly flexible objects.
“Until recently, prototyping flexible components was a time-consuming and cumbersome process,” said Fenner Drive product development engineer Stephen Heston “It was a big gap in the market, because so many engineered products utilize elastomeric parts. Without materials that closely approximate the properties of the end product, it is impossible to create truly functional prototypes.”
After discovering that 3D printing enthusiasts were trying to use existing Fenner Drives belting material as filament, Heston found that while it was not an ideal material in its current form, with a few months of tweaking it soon could become one. The final product has a textured surface that allows it to be used in most 3D printers with a spring loaded extruder. It has a low melt point and NinjaFlex retains its shape when other materials would splinter or crack.
NinjaFlex was released just last October and has already been used on a wide variety of projects. You can see an excellent video of someone using and abusing a custom grip for a BMX bike here. Not only does it look impressively durable, it seems to hold fine detail very well.
Most impressively however is the replica of a small childs defective heart that surgeons in Kentucky recently 3D printed using his CT scans. By printing a model one and a half times the actual size from a highly flexible material, the doctors were able to pre-visualize the best way to repair the defect without having to perform the risky surgery blind. The fact that the model only cost about $600 and most likely saved a small child’s life is actually pretty incredible. It also would not have been useful to the doctors if it had been printed from a less flexible material. You can watch the local news story here:
Of course no material is perfect. NinjaFlex isn’t going to replace PLA or ABS any time soon. It obviously lacks rigidity so it isn’t ideal for a lot of builds. It also doesn’t work very well if your printer doesn’t have a spring loaded extruder, as the material is too flexible and will often end up bending and creating a jam. And as you can see in this video of a 3D printed bracelet it can be quite messy and extra material will need to be extensively shaved off.
NinjaFlex is currently available in nine colours and is priced comparably to ABS and PLA. You can find out more about the product, or buy a few spools and try it out for yourself on Fenner Drives website.
PLA is biodegradable — it is one of the only common biodegradable plastics.
If you just leave it on your back lawn it won’t do much, but in an industrial composting facility it will degrade back to the lactic acid it ultimately comes from, which in turn will be metabolized by bacteria and fungi all the way to carbon dioxide and water.
Another point is that there are already flexible materials available for FDM printing — I know at least MakerBot sells a flexible filament made of polycaprolactone, which also happens to be biodegradable (though less so than PLA). Polycaprolactone is not rubbery like the NinjaFlex material, but it IS flexible.