Know Your Materials: HP 3D High Reusability TPA

Originally published on fastradius.com on November 10, 2020

SyBridge now offers HP 3D High Reusability TPA enabled by Evonik. Made specifically for HP Multi Jet Fusion technology, this thermoplastic polyamide powder is extremely lightweight and flexible with enhanced rebound resilience.

The most promising benefit of TPA is that it allows us to make parts that are unprintable with elastomers made for other 3D printing processes. MJF doesn’t require support structures like Stereolithography (SLA) or Carbon Digital Light Synthesis™ (DLS), so we have been able to create geometries and overhangs that aren’t possible to make any other way.

Mechanical properties of TPA

TPA’s flexibility and light weight are its major distinguishing characteristics. With a density of only 1.01 g/cm³, we’ve found it produces parts that are significantly lighter than those made of other additively manufactured elastomers.With a Shore-A hardness of 90, TPA is much stiffer than the other elastomers we use.

TPA has a high elongation at break in colder conditions, which many other elastomeric materials do not. This means TPA maintains its elastomeric properties in cold weather, so it won’t become brittle or break in the field — or on the ski slopes.

Key material properties of TPA

• Lightweight and Flexible
• Durable
• Can withstand cold temps better than most elastomeric materials
• Easy to process

Common TPA applications

TPA is a strong choice for parts needing high energy return and impact absorption. There are a handful of applications that benefit from elastomeric material that we simply haven’t been able to print due to technological limitations — until now. Some of the most promising applications we’ve identified for TPA are:

• Automotive components including air ducts, wire harness, bellows, fasteners, and more
• Sports equipment, especially winter sports equipment, balls of all sorts, and footwear
• Robotics grippers/shielding
• Airless tires
• Foam replacement applications

Designing a shoe with TPA

To learn more about the properties of TPA, the SyBridge application engineering team took on a design challenge; we chose to experiment with shoe designs to test the boundaries of the new material. While commercially available 3D printed shoes rely on 3D printing for one component of a shoe (the midsole in the case of the Adidas and New Balance), TPA allows us to make an entire shoe in a single print. It’s not possible to print a shoe with an enclosed upper section using a method that requires support structures, but HP MJF technology doesn’t pose that limitation.

Further, TPA allows us to create “fabrics” with  woven, flexible textures that function perfectly in the upper of an athletic shoe. Our engineers have gotten some good results with this technique, and we hope to have more to share soon.

Contact us today if you have an application that might work well with TPA. Our skilled team of application engineers will help you get the most of this material.