TPU is a thermoplastic polyurethane material that can be considered a bridge between rubber and plastic. Read part 1 to learn more about the elastomer.
NOTE: The Stratasys upgrade kit doesn’t just come with new material, but also new parts that are easily installed by the user to existing systems to optimize the machine for adapting to the different properties of the new FDM material.
The Stratasys upgrade kit comes with the following parts:
- QTY1 FDM TPU 92A Extrusion head
- QTY1 FDM TPU 92A filament spool, black
- QTY1 Installation Instructions
- QTY2 Modified Upper Y blocks
What’s new with the TPU head and Modified upper Y block?
The kit comes with a TPU print head which is optimized for materials with the elastomer-like properties and not compatible with rigid materials. The TPU head needs to be installed when you print with TPU and replaced with the ABS/ASA head when printing any other material. The TPU material also works with the QSR support material.
TPU head details:
- Layer height = 0.010”
- Head life:
- 700 hrs – Notification to order new head.
- 800 hrs – Notification to replace head. User will be able to continue using the head beyond the 800 hrs with the understanding that the reliability will decrease with increasing build time beyond 800 hrs.
- Head Throughput = 50% Slower than ABS (expect print to be 50% slower than an ABS print)
Modified Upper Y block:
Both Y blocks on the back of the machine are easily replaced by the user to avoid buckling which causes excessive friction in the previous design. The new Y blocks are media blasted on the interior and appear opaque compared to the clear design of the previous Y blocks.
Setting up and working with TPU 92A
TPU material spools loading behavior and storing the material
- Load time for TPU is slower for both model and support, approx. 60s vs 10s
- For rigid material the printer can push the filament back onto the spool when unloading, for TPU there will be a tail of material that needs to be pulled out when removing the spool.
- Proper storage of TPU material is critical as it is very hydroscopic and will absorb moisture.
- When removing spools from the system place the material spool in a MYLAR bag (included with spool) immediately.
- For extended non-sue period greater than 48hrs unload the material from the head and wind back onto the spool. Store in the material bay.
- Environments with high humidity should unload the material after 36hrs.
- If the machine has been idle with TPU material for more than 48hrs, unload the filament and cut off 6ft (1.8m) of the filament end and reload into the printer.
Unlike rigid materials (ABS, ASA, PC-ABS) TPU92A dos not require the offset calibration done in Z, only X and Y are required. This is because the material adheres so well to QSR support, the AUTO Z tip calibration is sufficient.
Accuracy and detail
- Parts are produced within an accuracy of: +/-.254 mm (.010 in), or +/-.003 mm/mm (.003 in/in), whichever is greater
- Z part accuracy includes an additional tolerance of -0.000/+slice height.
- Putting printed parts into a support removal tank may cause swelling of up to 0.5%, which can result in the part being out of the accuracy tolerance initially. Depending on part size and geometry it may take up to 72 hours for a part to shrink back to pre-tanked size.
- Due to the nature of the elastomer material, the visual quality of parts may not be as high as it is for rigid materials such as ABS or ASA on the F123 platform for fine feature details.
Important considerations when processing TPU parts for best quality and reliability
Orient for stability. Normally parts are oriented for function, aesthetics, speed, etc. with the expectation that part will build successfully. With the FDM TPU92A material, orienting for build success is the primary consideration. Then factors such as design intent and aesthetics can be considered. See below.
- Every print requires a full height purge part. The use of a purge part enables faster head swaps and better control of purge material which ensure part quality.
- Place the purge part close to the first part in the pack or next to the tallest part to minimize head movements.
Insight Settings – Modeler Setup:
Insight Settings – Support Setup:
Insight Settings – Toolpath Setup:
Insight Settings – Part Stabilization:
Contact us for any questions about the FDM TPU 92A upgrade and other Stratasys products!