TPU is a 3D printing material known for its elasticity which enables it to stretch and bend. Producing a high quality TPU printed part means understanding its properties.
TPU is a 3D printing material known for its elasticity which enables it to stretch and bend. Producing a high quality TPU printed part means understanding its properties.
In this article we will examine:
Part 1
1. Introduction to TPU
2. TPU Properties and Applications
3. TPU Shore Hardness
Part 2
1. What to Look for in a 3D Printer If You Want to Print TPU
Part 3
1. Why choose a Printer from Raise3D?
Thermoplastic Polyurethane, TPU, is a type of flexible and elastic material. This article will focus on TPU filament for FDM/FFF printing.
And while there is TPU filament available for 3D printing, TPU is a material that can be processed in more traditional manufacturing methods, such as injection molding. It is important to understand that TPU will have the same kind of elastic and flexibility whether it is printed as a filament, or processed in Injection Molding.
Injection Molding is an excellent manufacturing method for producing a large quantity of the same part. Parts that are produced with injection molding will always be solid. 3D printing is excellent for rapid prototyping, low volume production, and for testing out designs and parts.
It is misleading to think of 3D printing or injection molding as a superior manufacturing method to the other. Instead, 3D printing and injection molding are complementary methods of manufacturing. Each has their advantages and tasks they are better suited for.
TPU filament is more rigid than Thermoplastic Elastomer, TPE. It is important to understand that rigidity does not equate hardness. Rigidity is the material’s ability to bend. Softer filaments, such as TPE, can be more of challenge for a 3D printer’s extruders to process. Compared to TPE, TPU is a stiffer material, and is easier to print than TPE. However, TPU is still a flexible material and understanding its properties and applications is important for a satisfactory result.
TPU’s characteristics include rubber-like elasticity, tear and abrasion resistance, and durability making it suitable for uses requiring impact absorption and a soft-touch surface.
Examples of TPU 3D printed parts include tubes, insoles, seals, bushings and vibration dampeners. When pairing a hollow design with a flexible filament, like TPU, a softer, easily compressed part can be produced, like a shoe insole. If the design of the structure is for a more solid part or a part with a compressed interior, then an object like a helmet, can be printed using TPU as well.
Since TPU is a flexible material, it is important to understand its shore hardness. Checking the shore hardness of any material can give an idea of the differences in material because each material can register at different shore hardness.
Below are the different TPU options available from Raise3D and Raise3D’s Open Filament Program.
| Manufacturer | Approved Filaments | Shore Hardness |
| Raise3D | TPU | Shore A Hardness 95 |
| BASF | Ultrafuse TPU 64D | Shore D Hardness 58 |
| BASF | Ultrafuse TPU 95A | Shore A Hardness 92 Shore D Hardness 45 |
| BASF | Ultrafuse TPU 85A | Shore A Hardness 85 Shore D Hardness 29 |
| eSun | eTPU-95A | Shore A Hardness 95 |
| PolyFlex | TPU95 | shore A Hardness 95 |
Visit our OFP page to learn our printer recommendations for each of these filaments
When evaluating if a 3D printer is well suited for printing TPU look at the printer’s extrusion system. The softer a filament is, it lacks the rigidness to keep its shape. Although TPU is a more rigid filament compared to TPE and other flexible filaments, TPU is still a softer filament, especially when compared to other 3D printing materials.
The printer’s gear drives the filament through a printing path towards the hotend. A longer printing path is problematic for softer, flexible filaments like TPU because the filament gets squeezed and pushed for a longer distance. This is one of the most common reasons that cause a failed printing result.
A 3D printer with a shorter path from the gear to the hotend will avoid this issue. A 3D printer featuring direct drive will be better suited than a bowden style printer. Direct drive is mounted on the print head while the bowden system is mounted on the machine. This means the design of the bowden system is longer than a direct drive system.
Another feature that a printer can have that makes it easier and faster to print TPU is having more driving force from the gear. Since many printers slow down when printing TPU it takes longer to produce a TPU printed part.
An example of a printer with all a short printing path and a strong driving gear is the E2 desktop 3D printer. The E2 has the shortest printing path of all the Raise3D printers and the print head motors and gears are designed to optimize the feed gear power.
A printer with both a stronger gear and driving force will be able to have a longer distance for the printing path. For example, the Pro3 Series does have a longer printing path, but the interior of the print head is designed to feed the filament smoothly and has the bonus of two feed gears that work together because they are fitted to each other, allowing it to grip the TPU better.
The E2 and Pro3 Series are excellent options for printing TPU. The E2 features a unique extruder gear design making it well suited for processing flexible 3D printing materials, such as TPU. The E2 features an IDEX system enabling it to produce smaller parts repetitively in Duplicate and Mirror Mode.
The Pro3 Series is equipped with an independent modular extruder with a dual extrusion system which reduces clogging of filaments. The Pro3 Series line of printers includes the Pro3 and Pro3 Plus. The Pro3 has a build volume of 300 × 300 × 300 mm (11.8 × 11.8 × 11.8 inch), while the Pro3 Plus has a build volume of 300 × 300 × 605 mm (11.8 × 11.8 × 23.8 inch).
A good 3D printer manufacturer, like Raise3D, will provide a well-tuned template that can be used for good results with little work on the user’s end. Raise3D also offers an Open Filament Program to provide well tuned templates, and verifies third-party materials. Check for the OFP list of filaments here.
Another benefit of the Raise3D ecosystem. An advanced user can use a capable slicer like ideaMaker, to control and tune settings for each area of the model as needed. For example, ideaMaker can slow down the speeds or temperatures for more difficult details only in the layers where it is needed, and then run the rest of the part in normal settings.
Appendix
1. Shore Hardness
What is Shore Hardness?
Shore hardness is a reference point for the material’s hardness and flexibility. Shore hardness is scored from 0 to 100, and covers a scale from 00 Class to A Class, to D Class. A shore hardness score of 0 indicates that the material deforms/indents the most, while a score of 100 showed little to no deformationt all.
A Class measures a wide range of material types; from very soft and flexible to semi-rigid plastics with almost no flexibility at all. D Class measures hard rubbers, semi-rigid and rigid plastics. Having a shore hardness of 70A can move a material into the D Class. 3D printing materials, filaments, are generally registered in the A Class.
For additional information contact Raise3D.