Upgrading Stratasys F123 3D Printers for FDM TPU 92A Material – Part 1

Introducing a new material upgrade for the Stratasys F123 3D printer platform! Additive manufacturing continues to advance in the world of 3D printing. One of the newest elastomer material upgrades available for FDM printers is the FDM TPU 92A.

What is TPU 92A?

TPU stands for ‘Thermoplastic Polyurethane’ and is a type thermoplastic elastomer that can be considered as a bridge between rubbers and plastics. Thermoplastics are plastics that can be deformed under heat and will flow like a fluid in that state. This makes the material ideal for manufacturing processes such as: injection molding, extrusion, and compression molding, therefore ideal for the FDM extrusion process.

What does the 92A mean?

This is a measure of the materials hardness under the “Shore A” scale. The range of hardness is from 0 to 100 where higher numbers on the scale indicate a greater resistance to indentation. Harder materials and lower numbers indicate less resistance and softer materials. The A indicates the type of test method that was used, also materials on this scale are typically softer than the other scales (SHORE D).

Here are some examples of common materials and their Shore A hardness:

• Mouse Pad: 20A
• Rubber band: 25A
• Baby Bottle Nipple: 40A
• Door Seal: 55A
• Car Tire Tread: 70A
• Skate Board Wheel: 78A
• Leather Belt: 80A
• Hydraulic O-ring: 70-90A

What are the characteristics?

Excellent Toughness and Flexibility

TPU has an Elongation at break of 550%, this is an indicator that this material is very flexible and tough. It expresses the capability of a material to resist changes of shape without crack formation which means TPU can bend and stretch significantly more than materials with lower elongations before it will break. See the comparisons to NYLON and PC ABS below.

• TPU 92A  = 550%
• NYLON 12 = 30%
• PC-ABS = 6%

Superior Abrasion Resistance

This refers to the ability of materials or structures to withstand any method of wearing down or rubbing away by means of friction. This ability helps the material maintain its original structure and appearance and resist mechanical wear. TPU has an inherent slipperiness to it’s surface, that combined with the superior toughness characteristics of TPU give it superior abrasion resistance.

Good Impact/Shock Absorption

This refers to the material’s ability to absorb and dissipate impact energy. Due to the materials toughness and flexibility it also has good shock absorption characteristics which makes it good for isolation mounts, machine feet and over- molds.

Good Compression Set

The compression set (ASTM D395) of a material is the permanent deformation remaining after removal of a force that was applied to it. The term is normally applied to soft materials such as elastomers. For this material the compression set is 21% after 22 hours at 23̊C, this means that after the load is removed the material returns to 79% of its original thickness. Compression set is critical when designing gaskets and the designer needs to confirm that even after the compression set has occurred the gasket material still produces enough pressure to produce a good seal. An example of a material that has excellent compression set is PORON which has a 10% compression set.

What is it good for?

TPU is good for any application where flexibility and toughness are required, applications such as:

• Seals, gaskets
• Surface protection covers
• Mats, liners
• Bellows
• Wheels, rollers
• Hoses, tubes
• Ducts
• Over-molds
• Manufacturing Aids

The material is good for design validation for complex TPU parts. Parts can be printed and then validated/tested before expensive injection molding tools are built helping to reduce risk, cost and improve design/tooling turn around. It also allows for design iteration to occur before tooling constrains certain aspects of the design. It can also be used for low volume end use parts to be produced when volumes are to low for traditional manufacturing processes (injection molding).

Which Stratasys FDM machines can 3D print with this material?

Currently the Stratasys F123 3D printers support this material: Stratasys F170, F270, and F370