TPU 90A Powder is a tough SLS elastomer with high tear strength and elongation that is safe for skin contact. Use TPU 90A Powder to print strong and flexible parts for end-use applications, bridge manufacturing, or functional prototyping.

Recommended for:

• Low-volume production and custom manufacturing of end-use parts
• Functional prototyping and pre-production parts
• Soft molds and sheet metal forming dies
• Flexible jigs, fixtures, and masking devices

Formlabs recommends using a 20% refresh rate and an ambient air printing atmosphere for TPU 90A Powder to achieve consistent results. Formlabs does not recommend printing TPU 90A with an inert gas atmosphere as it provides no known benefit for this material.

See the table below for a comparison of relevant material properties:

To learn more about the performance properties of Formlabs resins, refer to the library of material properties data sheets.

Printing with TPU 90A Powder requires special considerations for print setting choice, part design and layout, printing, and post-processing procedures.

Benefits of V2.1 print settings

TPU 90A V2.1 print settings offer the following key benefits compared to V1.1 settings:

• Improved print times: up to 25% print time savings depending on part geometry
• Improved fine feature and lattice performance
• Improved dimensional accuracy
• Improved sifting times: TPU 90A Powder normally requires a 150 μm sifter mesh for the Fuse Sift, but V2.1 print settings allow you to use a 300 μm mesh.

Part design considerations

• Printability of fine features
• Fine features will resolve more clearly on V2.1 print settings than V1.1, but may not be true to model size. Make sure to test and evaluate the resolution and accuracy of fine features required and redesign your parts as needed.
• Lattice structure performance
• Depending on the lattice size and structure, part stiffness may be different between V1.1 and V2.1 print settings. You may need to redesign your parts to maintain their physical performance and behavior when switching between TPU 90A print settings.
• Dimensional accuracy
• Deviations of up to 5% are expected.
• When printing with V1.1 print settings, place parts roughly halfway up the build chamber and away from the build chamber walls for better Z-dimensional accuracy. When printing with V2.1 print settings, place parts near the bottom of the build chamber and away from the build chamber walls for better Z-dimensional accuracy.
• Most parts print with greater dimensional accuracy when using V2.1 print settings. You may need to redesign your parts when switching between TPU 90A print settings.

Layout considerations

• Part accuracy variation within the build
• When printing with V1.1 print settings, place parts roughly halfway up the build chamber and away from the build chamber walls for better Z-dimensional accuracy. When printing with V2.1 print settings, place parts near the bottom of the build chamber and away from the build chamber walls for better Z-dimensional accuracy.
• Avoid abrupt changes in lased area
• V2.1 settings can, in some cases, result in visible banding on parts with abrupt changes in lased area around them. Correct for this by changing the layout of your parts or adjusting your printer’s Bed Temperature Target.
• Bulky parts (both V1.1 and V2.1 settings)
• TPU 90A Powder can oversinter when printing large or bulky parts. Such parts may be avoided or hollowed out for best results.

For the best results, follow Formlabs design specifications for SLS printing. Refer to the support article Starting a print (SLS) to open the model in PreForm, orient it, and send it to the printer.

Using TPU 90A with the Fuse 1+ 30W

TPU 90A has a tendency to settle over the course of days and requires stirring to bring the powder back to a state where it will flow successfully. Stir the powder in the hopper before printing, particularly if the printer has been sitting unused for more than three days. Take care not to strike or damage the agitator at the bottom of the hopper when stirring the powder.

When printing jobs that use the entire print volume, fill the powder hopper to the brim, past the viewing window.

Using TPU 90A with the Fuse 1

Due to the Fuse 1's sensitivity to powder jams, only fill the Fuse 1 hopper with slightly more powder than the amount required for an upcoming print job as indicated by Preform. The weight of additional powder can lead to powder clumping and subsequent underdosing. Print smaller jobs with fewer parts whenever possible to help prevent jams.

Remove the debris catcher from the hopper before printing with TPU 90A, as the material will clump if the debris catcher is left in place.

If the Fuse 1 has not printed within the last week and there is TPU 90A Powder in the hopper, empty the hopper completely by following the instructions below:

1. On the Fuse 1 touchscreen, go to Settings > Calibration.
2. Tap Empty Hopper to empty all powder contained in the hopper into the build chamber. This routine may need to be run more than once to fully empty the hopper.
3. Remove the build chamber from the printer and empty it into the Fuse Sift.
4. Reinsert the build chamber into the Fuse 1.
5. Refill the hopper with enough powder to complete the desired print job.
6. Mix the filled hopper with the recommended stirring rod or other wooden rod.

To check whether your Fuse Sift model is compatible with TPU 90A Powder, look for a gray sticker that indicates the version number. This sticker will either be in the cartridge drawer or on the back panel of the unit next to the Ethernet port.

If your Fuse Sift does not have this sticker, please contact Formlabs Support or your certified service provider before using your Fuse Sift with this material.

Before using TPU 90A Powder, check that the firmware on your Fuse Sift is up to date.

Best practices for sifting TPU 90A Powder:

• Sift and depowder your parts when the powder cake is still warm but not unsafe to handle, ideally in the 35–40 °C range. Unpacking at room temperature can be difficult, and may result in powder that is caked onto parts and is difficult to work through the sifter mesh.
• Use a dental pick or other similar tool to remove material stuck on printed parts.
• Check the sifter mesh for clogs and clean it with compressed air and a brush.
• Sift TPU 90A Powder using the 150 micron sifter mesh included with the Fuse Sift.
• Print and use mesh clearing balls.
• Consider pouring the entire build, or portions of it, directly onto the sifter mesh rather than onto the surface grate.
• When sifting powder, use a gloved hand to gently work the powder through the sifter mesh.

TPU 90A Powder usually requires a longer sifting time than other SLS powders. If sifting time increases, the sieve may have become clogged with powder. If this occurs, clean or replace the sieve. TPU 90A Powder is compatible with the 150 micron mesh that comes standard with the Fuse Sift.

Sifting TPU 90A Powder

Formlabs recommends printing three mesh clearing balls in TPU 90A Powder and placing them on top of the sieve to reduce powder clogging.

1. Make sure your printer’s firmware is up to date.
2. Download the mesh clearing ball STL file and open the file using the latest version of PreForm. Duplicate the mesh clearing ball so you have three models.
3. Send the print job containing the mesh clearing balls to the printer. The mesh clearing balls should only be printed using TPU 90A Powder.
4. Check that the hopper contains sufficient powder for the print.
5. Print the mesh clearing balls.

6. After the print is complete, allow the mesh clearing balls to cool while they are still inside the printer for at least 60 minutes.
7. Extract the cooled prints using the Fuse Sift.
8. Media blast or further post-process the mesh clearing balls once extracted.
9. After the mesh clearing balls are fully post-processed, remove the surface grate on the Fuse Sift to gain access to the sifter mesh beneath.
10. Vacuum and brush the sifter mesh.
11. Place the three mesh clearing balls on top of the sifter mesh.
12. Place the surface grate back over the sifter mesh.

Filling a powder cartridge with TPU 90A Powder

In some instances, TPU 90A Powder may not flow smoothly through the Fuse Sift hoppers, resulting in failed powder dosing attempts. If this happens, tap Manual Dosing. Follow the instructions on the touchscreen, tapping Dose Used and Dose Fresh while manually stirring the powder in the hoppers. Use the recommended stirring rod or other wooden rod to agitate the powder in the fresh and used powder hoppers. When mixing the fresh powder hopper, uninstall the entire rectangular cover and set it and its screws aside for better access.

When blasting parts printed with TPU 90A Powder, Formlabs recommends using 40–50 grit (313–387 μm) glass media. This is larger than the 212–300 µm / 50–70 mesh size media generally recommended for the Fuse Blast. For parts printed in TPU 90A, this leads to:

• Improved surface finish consistency and quality
• Decreased loose powder shedding
• Faster complete depowdering of TPU 90A parts
• Improved cleaning of complex geometries, blind holes, and latticed parts

Stray powder particles can cause print failures in future print jobs if not properly cleaned out after each print. Perform the following maintenance tasks between prints:

• Inspect and clean the optical cassette
• Inspect and clean the IR sensor
• Clean any powder that fell below or around the build chamber
• Clean both powder troughs and the area around the recoater’s path using a compliant vacuum with static dissipative components
• Inspect and clean the recoater if necessary
• Inspect your parts for print defects and fine tune your printer if necessary

Cleaning the top of the print enclosure

Powder can accumulate at the top of the print enclosure, particularly on the runways, the areas between the powder troughs and the top of the build chamber. This excess powder may fuse and be dragged into the build chamber during subsequent prints. Vacuum this area thoroughly to help prevent print failures.

Vacuuming the troughs

Close the print enclosure door and move the flipper motors to dislodge powder for cleaning.

To move the flipper motors:

1. Close the print enclosure door.
2. On the touchscreen, tap the wrench icon. The Maintenance menu appears.
3. Tap Motor Moves. The Motor Moves screen appears, which allows you to manually activate various motors in the print enclosure.

6. Tap the CW, CCW, and Home arrows under the Flipper (Left) and Flipper (Right) headers to rotate the left and right flippers clockwise, counterclockwise, or back to their home positions. Repeatedly move the flippers and vacuum the powder troughs until they are clean. In particular, ensure that the inner edge of both powder troughs as well as any adjacent components are free of powder.

Cleaning the recoater

Fine tuning your printer

If you observe any of the following defects in your printed parts when using TPU 90A Powder, consider reducing the printer's Bed Temperature Target. Decrement the setting by 1–1.5 °C and retry the print.

• Excessive thermal bleed-through, leading to wavy surfaces
• Dark sintered regions in print videos
• Banding on print surfaces
• Periodic bands may be the result of build chamber drive motor issues.
• Thermal bands in areas with abrupt cross section changes, such as those shown here, may be improved by reducing bed temperature target if build layout changes are not possible.

Fuse 1 generation printers, the Fuse Sift, and related accessories are designed to be used with only one powder type at a time. Make sure to clean each device thoroughly, following Formlabs instructions, before switching powder types. Mixing powders can lead to print failures or permanent damage to the machine.

If you plan to regularly print in multiple different materials, Formlabs recommends dedicating a separate printer and Fuse Sift for each material type.

TPU 90A Powder melts at a lower temperature than other Formlabs SLS powders. As a result, be sure to thoroughly clean your printer, Fuse Sift, and build chambers when switching materials to or from TPU 90A. Follow the procedure listed below as applicable.

Consult the following support articles for additional information:

• Switching SLS powder types (Fuse 1/Fuse Sift)
• Cleaning all powder out of a Fuse 1
• Cleaning all powder out of a Fuse Sift
• Cleaning all powder out of a build chamber