Best Flexible 3D Printer Filament

Best Flexible 3D Printer Filament

There’s a wide variety of filament materials available to use in our 3D printers, and one that stands out the most is flexible filament. The most common types are TPE and TPU.
Unlike the more popular PLA and ABS, flexible filaments have a soft rubber-like texture.

This unique property opens up a whole new world of possibilities for your 3D printing.

The advent of flexible filaments has really widened the range of complex objects that can be made on 3D printers.

In this article, I will discuss what you need to use flexible filaments, what you can make with them, and I’ll review the best flexible 3D printer filaments available on the market today.

What is A Flexible Filament?

To get an idea of what flexible filament feels like, think of those rubber-like phone covers you can get that protect your smartphone, they are flexible but not soft.

Flexible filaments are made with Thermoplastic Elastomers, commonly known as TPE, which is a type of plastic that combines the properties of rubber and hard plastic.

As the name indicates, the flexible property allows the plastic to stretch and bend very easily before returning to its original shape.

Flexible filaments can also withstand much tougher environments in comparison to ABS and PLA as they have much better resistance to chemicals such as oil and harsh weather conditions.
The two most common types of flexible filament are TPE and TPU (Thermoplastic Polyurethane).

What is Shore Hardness?

Shore Hardness is a method of measuring the hardness of soft plastics. It allows you to compare different materials to determine how hard or soft they are.

When you look at the tech specs for a flexible filament, you’ll see a Shore Hardness value, usually in the range of 85A (softer) to 95A (harder).

The lower the number, the softer the material. The letter ‘A’ refers to the scale. This will either be ‘OO,’ ‘A,’ or ‘D’ where OO is very soft, A is for soft, and D is for harder materials.

To give you an idea of what Shore Hardness mean here are some common examples:

Gel Insole = 30OO
Mouse Pad = 20A
Rubber Band = 25A
Smartwatch Band = 70A
Soft Skateboard Wheels = 78A
Hard Skateboard Wheels = 98A
Truck Tires = 50D
Lego Block = 60D
Hard Hat = 75D

The way your 3D printed object feels will also be dependent on how thick it is. You might think filament that’s as hard as skateboard wheels won’t be very flexible, but when you’re printing an object that’s only a few millimeters thick, it will be surprisingly flexible.

The Shore hardness scale was invented by Albert Ferdinand Shore in the 1920s. He developed a device called a durometer which uses a known force to press a pointed foot into a sample of the material and then measures the indentation that is created.

What Can I Print With A Flexible Filament?

You will most likely want to print using flexible filament because you have a specific application in mind. However, you can also use TPU filament for its superior properties of oil and weather resistance, as well as it being much less brittle compared to PLA and ABS.

Here are some ideas of what you can 3D print with flexible filament:

RC car tires – you can design custom tread patterns, or even print both the wheels and tire together.

Handlebar grips – for your Razor or any type of bike you can print completely unique grips in whatever color you choose.

Non-slip feet – if you have any gadgets or appliances that slide across your desk when you’re using them you can easily print perfectly sized feet to keep them steady.

Protective cases – we’re used to putting perfectly fitting cases around our smartphones and tablets, but with a 3D printer, you can make a bespoke flexible bumper case for anything you own!
Due to the flexibility as well as the durability of this material, it is finding its way into manufacturing products in various sectors of the industry as well as for personal use.

Flexible plastics are now used in many household appliances, medical devices, auto parts, footwear, power tools, mobile phones, inflatable rafts, sporting goods, etc.

In fact, the common use of TPE in manufacturing has made it easy to cross over from the large-scale manufacturing of many products to make them with 3D printers.

What Is the Difference Between TPU and TPE?

There’s a lot of confusion over which filaments are TPU and which are TPE. This isn’t helped by manufacturers using the wrong terms themselves!

For 3D printing, all you really need to know is that flexible filament used to be very soft and labeled as ‘TPE’ but more recently slightly more rigid filament has been more popular, and this has been labeled as ‘TPU.’

Hence, people generally think of TPE as being soft and TPU as being more rigid. For 3D printing, TPU can be considered the successor to TPE.

TPU is very similar to TPE, but it has a shore hardness in the range 94A-95A which makes it easier to print in 3D printers that couldn’t previously work with soft TPE.
In fact, nearly all 3D printer flexible filaments are actually made of TPU no matter what they’re called!

Is TPU Toxic?

In general, TPU is not toxic however it is not considered food safe so it shouldn’t be used in any situation where it comes into contact with food or could be eaten itself.

TPU is used in many medical applications, for example, oxygen masks and waterproof mattresses in preference to PVC.

TPU is also biodegradable after 5 years in soil, so it is not harmful to the environment.

However, it’s important to remember that any synthetic plastic could be potentially toxic, and its safety depends on numerous factors such as whether it contains impurities.

Tips For Printing With Flexible Filament

Because the material properties of flexible filaments such as TPU are so different from traditional materials like PLA, printing with them may take a little trial and error.

To give yourself the best chance of success, you should make sure you’re using printer settings similar to the following:

High extruder temp, low bed temp – it is recommended to maintain the extrusion temperature at 200 to 220°C. Also, it is best to have the heated bed low or off at a temperature of 20 to 60°C.
No rafts – you should avoid the use of rafts when using flexible materials. It can create issues since the base layer of a raft has much higher extrusion rate.
Slow feed rate – you should try to print at a slow speed when using flexible filaments. They have a tendency to bend under high stress, and printing faster can cause the extruder to clog up. The recommended setting is 5 to 25mm/s. However, you can also go as high as 35 mm/s. I would recommend starting slow and working your way up gradually depending on the results.
Reduce filament travel –  in a Bowden extruder flexible filament has a tendency to bend as it is pushed by the extruder if you can shorten the distance it as to travel and use PTFE tube that is closer in size to the filament, it will have less chance to kink.
Limit retraction – flexible filament will suffer when you use standard retraction settings as it will simply be stretched by the extruder rather than pulled back. You should limit your retraction as much as possible.
Spool resistance – with normal filament the extruder pulls on the filament which then unwinds it from the spool as it is used. However, flexible filament may stretch as it is pulled against the resistance of the spool and cause under extrusion.
Don’t get stuck – flexible filaments have good adhesion and work well on glass and aluminum surfaces. However, if you have a grippy build surface like PEI I would recommend using a painter’s tape or even oil to prevent them sticking too hard to your build surface.
Keep it cool – You should use a cooling fan which will make it possible to retain finer details of the prints without any sagging. However, I would recommend not using the fan in the first couple of layers until you get a good bed adhesion.
Reduce layer height – it is better if you print at a reduced layer height in the range of 0.1mm – 0.2mm. This height requires much less plastic and will allow the extruder to use a lower feed-rate which relieves the extra burden on the filament.
Humidity – It is important to keep your flexible filaments dry. If you store them in a humid environment, you can dry them out by heating the filament in an oven at 200°F for about six hours and then switch off the oven and let it cool down to room temperature. You can also dry the filament in a vacuum oven within an hour.

Flexible Filament Reviews

SainSmart Flexible TPU Filament

SainSmart Black Flexible TPU Filament is known for its quality and flexibility. With its higher Shore hardness, it’s a great choice for your first flexible filament as it is easier to print than something like Ninjaflex.

Specification

• Shore hardness value: 95A
• Diameter: 1.75mm (+/- 0.05mm)
• Extruder temperature: 195 – 230°C
• Platform temperature: 40 – 60°C
• Net weight: 0.8 kg
• Roundness: 1.75mm (+/- 0.03mm)
• Dimensional Accuracy: (+/- 0.05 mm)

Features

• Material: Flexible TPU
• It is available in a range of 14 colors
• Excellent bed adhesion
• Packaged: Vacuum sealed with desiccant
• Standard size spool to fit most 3D printers

Opinion

• The filament produces really tough parts, so it’s great for high-stress objects.
• It prints well on a Bowden extruder at very slow speeds (10mm/s)
• The clear colors are a little cloudy, but the colors are bright and look good.
• It is also very easy to use on a direct drive extruder and compatible with all the FDM printers that accept 1.75 mm filaments.
• Great for all types of projects like phone cases, shoe insoles, drone parts, etc.
• Some customers report inconsistency in the size of the diameter. Others found it to be well within tolerance so there may be some differences across batches.
• Customers seem happy with the support service, and when an order does go wrong, for example, quality issues, Sainsmart is quick to respond and rectify.

NinjaFlex TPE Filament

NinjaFlex is one of the first flexible filaments on the market. They are well regarded but also well known for producing a soft filament that can be difficult to print if you don’t have a direct drive or modified Bowden extruder.

Specification

• Shore hardness value: 85A
• Diameter: 1.75mm and 3.00mm
• Recommended extruder temperature: 210 – 225°C
• Recommended platform temperature: 30 – 40°C
• Net weight: 1.75mm filament spool = .50 kg
• Net weight: 3.00mm filament spool = .75 kg
• Abrasion Resistance: 0.08 g
• Dimensional accuracy: Consistent

Features

• Material: Flexible TPU
• It is available in two sizes, 1.75mm and 3mm.
• Suited for 3D printers with direct drive extruders
• A wide variety of colors are available with unique shades and names like Mustard and Marsala!
• Print speed: 10-20 mm/sec (top and bottom layers)
• Infill speeds: 15-35 mm/sec (layer 2+)

Opinion

• NinjaFlex may not work effectively in 3D printers which are fitted with the extruder motor away from the heating block (Bowden). However, the filament works well with the printers which have the extruder motor positioned just above its heating block (direct drive).
• I would advise you to use blue painters tape on your bed as it can be quite hard to remove.
• You should use a cooling fan from layer 2 onwards.
• Very good quality filament with consistency across colors and batches.

YOYI Flexible TPU Filament

The YOYI 3D Filament Manufacturing company offer a wide range of quality 3D Printer Filaments, and TPU flexible is one of them. It’s a popular choice for users of 3D printers with Bowden style extruders as its higher Shore hardness makes it easier to print.

Specification

• Shore hardness value: 95A
• Diameter: 1.75mm
• Recommended extruder temperature: 200 – 210°C
• Recommended platform temperature: 30 – 40°C
• Extruder nozzle: 0.4-0.8mm
• Net weight: 0.8kg
• Roundness: (+/- 0.03 mm)
• Dimensional Accuracy: (+/- 0.05mm)

Features

• Material: Flexible TPU
• It is available in two colors, black and red.
• Packaged vacuumed sealed with Desiccant inside.
• It has been tested to 120mm/s.
• The customer ratings are amazing.
• Highly compatible with lots of 3D printers.

Opinion

• Prints very well but you should keep the speed below 30mm/s.
• Users find YOYI TPU to be quite prone to stringing.
• It’s a good choice for Bowden extruders.
• The spool can be too tightly wound resulting in stretching and under extrusion. It’s worth unwinding as much as you need and winding back on carefully to avoid issues.

SUNLU TPU Filament

SUNLU 3D Printer filaments have been designed to give the best user experience, but let’s see if the specifications and features meet the required standard.

Specification

• Diameter: 1.75mm
• Recommended extruder temperature: 190-210°C
• Recommended platform temperature: 50°C
• Net weight: 1kg
• Print Speed : 50 – 100 mm/s
• Dimensional accuracy: (+/- 0.02 mm)
• Recommended Storage Temperature: -20 to 50 °C
• Length: 330M / 360 Yard

Features

• Material: Flexible TPU
• 100% Zero Bubbles
• It is available in 4 colors: black, blue, green and white.
• Packaging is vacuumed sealed along with a desiccant pack.
• The filaments are in full compliance with the restriction of hazardous substance (RoHS) and free from hazardous substances.
• Backed by a 1-year warranty, but within the first 90 days, you can claim a refund.

Opinion

• You may get some stringing.
• Removing the printed object from the bed is easy. However, you mustn’t try to pull it out, instead, gently use your scraper.
• After measuring the diameter in different places, it’s good to see a nice consistency.
• Many consumers mentioned that it is a great product at this price point.
• The filament is durable as well as flexible but noticeably more rigid than Ninjaflex.

3D BEST-Q Flexible TPU Filament

The company claims that their filaments are the best quality. Let’s discuss some details and find out if the customer reviews on the 3D BEST-Q Flexible TPU Filament are supporting this claim.

Specification

• Shore hardness value: 95A (approx.)
• Diameter: 1.75mm
• Recommended extruder temperature: 200-220°C
• Recommended platform temperature: 50°-80°C
• Net weight: 1kg
• Dimensional accuracy: (+/- 0.03 mm)

Features

• Material: Flexible TPU
• Available in 8 color choices.
• It has good adhesion between the layers.

Opinion

• This filament falls into the category of the higher end for stiffness.
• 3D Best-Q doesn’t require as much heat as some of the other TPU filaments.
• It has a nice mild smell.
• If you are looking for a rubbery material, then this may not be suitable for you. It will produce a sturdy plastic feel with sufficient flex, something like a case for a smartphone.
• It is a very cost effective filament and produces good prints.
• It does not jam on the extruder because of the higher shore hardness.
• Does not have any bubbles.

3D Solutech FLEXCLR TPE filament

The 3D Solutech FLEXCLR TPE filament has been tested on various printers and produced good results. It attracts good ratings and positive feedback from the buyers.

Specification

• Diameter: 1.75mm
• Recommended extruder temperature: 200-220°C
• Net weight: 1kg
• Roundness: (+/- 0.03 mm)
• Dimensional accuracy: (+/- 0.03 mm)

Features

• You won’t have any problems with bubbles or residues.
• The heating bed is not required.
• The color availability is only clear.
• The company offers a 90-day return hassle free warranty.

Opinion

• You need to disable retraction to eliminate or reduce any stringing.
• It is fairly easy to remove from the bed.
• The price is very economical.
• The filament material is flexible, however, not overly stretchy.
• There were a handful of comments about people receiving the wrong color. For example, they received green instead of clear.

Ziro TPU Filament

The Ziro TPU Filament gets fantastic ratings with many satisfied customers. Let’s dive into the finer details of this filament.

Specification

• Diameter: 1.75mm
• Recommended extruder temperature: 200-220°C
• Net weight: 0.8kg
• Print Speed : 20 – 40 mm/s
• Roundness: (+/- 0.05 mm)
• Dimensional accuracy: (+/- 0.05 mm)

Features

• It comes to you vacuumed sealed with a bag for your used filaments.
• Material: Flexible TPU
• You get the choice of 3 colors.

Opinion

• This material is bendable and yet very strong and durable.
• It is recommended to use the 0.4mm nozzle or larger when you use this filament.
• It is not as flexible as Ninjaflex.
• For some, it was initially difficult to feed into the extruder.
• To get the best results, print at a slow speed and disable retraction.
• Excellent customer service. Someone had a problem with the spool, and they were very quick to replace it.

Pxmalion TPU Filament

Pxmalion is a known name in the world of 3D printing, and this TPU filament is their recent launch to get into the flexible printing.

Specification

• Shore hardness value: 85A
• Diameter: 1.75mm
• Recommended extruder temperature: 210-230°C
• Recommended platform temperature: 30-40°C
• Net weight: 1kg
• Roundness: (+/- 0.03mm)
• Dimensional accuracy: (+/- 0.03mm)

Features

• Material: Flexible TPU
• Compatible with most 3D printers.
• No bubbles and dust free.
• It comes to you in a vacuum sealed plastic bag.
• It adheres very well to most beds like glass, tape, and aluminum.
• Grease and oil resistant.
• Minimal warping.

Opinion

• It is strong and flexible but very sensitive to the correct temperature of the hot end.
• Not an easy material if you are new to 3D printing.
• If you get problems with layer adhesion, try raising the print temperature, and it should work fine.

Pinrui TPU Filament

This flexible Pinrui TPU printer Filament is made of a soft material like rubber. It is similar to TPE but prints easier and harder than TPE.

Specification

• Shore hardness value: 95A
• Diameter: 1.75mm
• Recommended extruder temperature: 200-220°C
• Recommended platform temperature: 30-40°C
• Melting Point: 200°C
• Net weight: 0.8kg
• Print Speed : 30.0 mm/s
• First layer speed: 50%
• Dimensional accuracy: (+/- 0.03 mm)

Features

• Material: Flexible TPU.
• It comes in blue color.
• Should be printed slowly at 15-30 mm/s printing speed.
• Delivered Vacuumed Sealed With Desiccant inside.
• It is abrasion and chemical resistant.
• Compatible with most 3D printers.

Opinion

• The colors look very bright.
• The layer adhesion is excellent.
• Using a cooling fan helps with stringing.

Conclusion

Regardless of whether you make a smartphone cover or a pair of shoe insoles, any of these flexible filaments will do the job.

They are different in some specifications, and some are easier to use than others. But overall, they should meet most of your printing needs.

After reviewing so many filaments, I would recommend SUNLU TPU Filament. It’s very competitively priced, and it gives a great print quality.
The dimensional accuracy is also within limits, and this product is available in some attractive colors.

The reviews and ratings for this filament are excellent, and the great majority of consumers are very satisfied with their printing results.

All in all, it’s a great all-rounder out of so many flexible filaments.

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