FLEX

Flexible materials can be tricky for beginners, with the filament going out somewhere in the middle of the extruder, extreme stringing, or adhesion issues. It’s also easy to get confused by their names and their hardness. For example, Shore 80A is softer than Shore 40D and Shore 40D is harder than Shore 20D. To make things simple: Shore A is used to measure softer stuff Shore D is used to measure harder stuff.

There are various types of different flexible materials available: NinjaFlex, PolyFlex, RubberJet, TPA, TPC, TPE, TPU, PP, Soft PLA, PEBA and the list goes on... The most common two are:

• TPE - thermoplastic elastomers
• TPU - thermoplastic polyurethane. 
  

Less common flexible materials are thermoplastic copolyester (TPC), thermoplastic polyamide (TPA), and then the arguably flexible materials like PP (Polypropylen) and Soft PLA, a purposely weakened version of PLA. Regarding NinjaFlex, PolyFlex, RubberJet, and so on, these are just fancy commercial names to stand out, but in most cases are TPU or TPE.

Printability of flexible filament

Printing with flexible filaments can be challenging at first, but there are a few tips that can drastically increase your print success rate. For successful printing with soft & flexible filaments, please follow the following tips:

1. Start your journey with flexible filaments with a harder, less soft material.
2. Decrease your printing speed. Start with 10 mm/s and slowly increase the printing speed up to 30 mm/s
3. Turn off completely retractions. Retractions don't work with flexible filaments as they only stretch the filaments in the extruder and lead to inconsistent extruding pressure.
4. Use as a bed adhesive regular office tape/scotch. As basic office tape is made from PP (polypropylene), it reacts perfectly with most flexible materials creating the perfect base material. If you're following this tip, it should not be even necessary to heat the hotbed. 
5. If you're having adhesion issues, make sure to addopt a specialized adhesives for flexible filaments, like Magigoo Pro Flex.

Some flexible filaments show lower adhesion to conventional 3D-printing build surfaces and a high tendency to warp. Others tend to stick too well to bare 3D printing surfaces such as glass and PEI. 

Tips: For larger prints and filaments with a high shrinkage rate, a 20 mm brim is recommended. In cases of excess adhesion, it is recommended to wet print bed with a small amount of water, slowly apply it below the part, this should make the part removal easier.

Flexible filaments are not compatible with long bowden extruders as their flexibility makes an uneven pressure in the extrusion mechanism. 

Mechanical and thermal properties of flexible filaments

Thermoplastic rubbers exist as co-polymers or a polymer blend, generally of a plastic and a rubber. This imparts both thermoplastic and elastomeric properties. As a result, these materials have the advantage of being able to stretch to moderate elongations and return to their original shape. Additionally, these materials have very good thermal properties, material stability, chemical resistance, and are more cost-effective to produce. As a result, these materials are highly sought in industrial applications.

Browse all flexible filaments in stock in our warehouse in Senec, Slovakia. For comparison, see also TPU and TPE.