Stratasys helps with Space Station's Mobile Freezers

Published 06/01/2015

Kelly Rantuccio | Accounting/Marketing Specialist 

ULTEM 9085 is most known for being a high temperature and chemical resistant material but did you know that it can also be used for under freezing conditions? 

Polar Unit Space FreezerStratasys had the recent opportunity to assist with engineers and scientist at The University of Alabama Birmingham Center for Biophysical Sciences and Engineering.  They were in the works of developing freezer units capable of reaching temperatures as low as -160°C.  Their most recent project, The Polar Unit, is one of their first designs incorporating 3D printed components.  By using this technology, it helped save significant interior space of the freezer!

The Polar Unit's purpose is to export biological samples to the International Space Station to be tested.  There are currently 3 Polar Units on deck with 14 more scheduled for the near future!

The engineers and scientist at The University of Alabama Birmingham were challenged by the unit's interior liner and were thinking of possibilities to maximize the interior space.  The initial concept for the freezer was to use flt machined pieces of Polyether ehter ketone (PEEK) but this did not work because it did not have the ability to obtain the curvature design.  It was also rejected because of inaccurate tolerances and different levels of sheet thickness.  Additional jigs and fixtures would also be necessary to join pieces, compromising more space. 

Polar Unit Space FreezerStratasys was able to print this complex shell structure in one build on the Fortus 900mc.

“At first, we continued the line of thinking similar to thermoforming, in which many pieces would be 3D printed and joined together,” said Daniel Sealy, Mechanical Engineer at CBSE. “But after some research, we realized there were 3D printers with a large enough printing volume that the entire shell could be 3D printed as a single piece. This led us to where we are now. We had to go through learning about how to design for 3D printing and what types of geometry worked well, but it seems to be working great.”

According to Sealy, the Polar unit will test the long-term effects of zero gravity on biological samples, including human blood, cells and urine.  Three Polar units launched in February aboard the SpaceX CR-5 Falcon 9.

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