FDM Printed PLA in Cryogenic Environments
21 Feb 2025 -
Last update 21 Feb 2025
6 mins
Warning
Safety Warning: Working with liquid nitrogen and cryogenic materials involves significant safety risks. Liquid nitrogen is extremely cold at 77K (-196°C or -321°F) and can cause severe frostbite upon contact with skin. It also rapidly evaporates into nitrogen gas, which can displace oxygen and create asphyxiation hazards in enclosed spaces. When conducting experiments with cryogenic fluids, always wear appropriate personal protective equipment, including cryogenic-rated gloves, safety goggles, and a face shield. Ensure proper ventilation and handle materials with tools designed for cryogenic use. This article shares my personal experience and should not be considered a substitute for professional training and safety protocols. Never handle cryogenic liquids without getting trained upfront and without knowing what you are doing.
Introduction
A few months ago, I explored the use of PLA in vacuum environments, as detailed in my previous article: 3D printed parts using PLA and standard FDM process in vacuum. This time, I’m taking it to a different level—how does PLA behave in cryogenic conditions?
Cryogenic applications involve extremely low temperatures, typically below -150°C (-238°F), where materials often exhibit unique physical properties. Liquid nitrogen (LN2) is one of the most common and accessible cryogenic fluids, widely used due to its low cost and availability. It boils at 77K (-196°C or -321°F), meaning that the surface of the liquid nitrogen is always at this temperature, providing a consistent cryogenic environment for experiments and industrial processes.
Liquid nitrogen is often used to cool high-temperature superconductors, preserve and fixate biological samples in electron microscopy, and provide cryogenic cooling for medical applications, industrial freezing, and scientific research setups such as electron spin resonance or other quantum mechanical experiments. Its versatility and cost-effectiveness make it an ideal choice for a wide range of cryogenic needs.
All prints shown here were produced using a Creality Ender 3 printer (note: this link is an affiliate link, this pages author profits from qualified purchases). While it is considered a budget printer, it has proven to be reliable and practical for everyday use. Though it lacks the capability to handle specialized filaments, it offers a solid and affordable option for quick prototyping and general-purpose prints when no exceptional requirements are needed. Personally, I prefer my fully self-built printer for more advanced projects, but the Ender 3 remains a useful alternative.
The PLA used for this experiment was ecoPLA from 3DJake. While this filament is quite affordable and suitable for most applications, it does present some challenges with consistency. I occasionally need to reduce print speeds for detailed or thin structures due to slight variations in viscosity. Nevertheless, ecoPLA generally meets the needs of typical projects without significant issues.
I used Cura as the slicer for all prints. Fortunately, Cura is available for FreeBSD (at the cad/cura port), which is my main desktop operating system.
Disclaimer: While the idea for this post originated from my experiences at work, the content and opinions expressed here are entirely my own and are not associated with or endorsed by my current employer.
- Why PLA in Cryogenic Applications?
- The Experimental Setup
- Practical Application
- Preliminary Observations
Why PLA in Cryogenic Applications?
The motivation behind using PLA in this experiment was primarily its easy availability, the quick prototyping capabilities offered by FDM 3D printing, and simple curiosity. Additionally, professional cryogenic equipment and materials are often quite expensive, making it worthwhile to explore more accessible alternatives. The application that was then realized was to create simple structural spacers for liquid nitrogen lines inside a vacuum chamber at high vacuum levels as mechanical supports.
The Experimental Setup
I designed and tested two different crucibles made of PLA to play with cryogenic compatibility of PLA.
Crucible Design 1: Thin-Walled Cylinder
The first crucible design featured a simple thin-walled cylinder with a flat bottom, measuring 100mm outer diameter, 96mm inner diameter, with 2mm wall width and 2mm thickness of the lower surface. The print parameters included a 0.2mm nozzle, gyroid infill at 10%, and 4 walls and bottom layers.
When filled with liquid nitrogen, the bottom plate ripped off due to the extreme thermal stress at the edges, while the remaining structure maintained its shape without visible damage. However, this design ultimately proved unsuitable for cryogenic applications.
Crucible Design 2: Reinforced and Rounded
The second crucible design featured a 70mm outer diameter, 60mm inner diameter, with a half-spherical bottom of 60mm diameter and 5mm wall thickness. All sharp corners were printed with a 1.5mm radius fillet to improve stress distribution and durability under cryogenic conditions. To enhance resilience, this design incorporated a 5mm wall thickness on the top and a rounded internal shape. The gradual redirection of stress in the walls made this design much more robust, withstanding multiple floodings with liquid nitrogen directly from room temperature without failure.
This crucible also underwent evaporation tests to measure how long it takes for the full volume to evaporate. PLA has a known thermal conductivity of around 0.13 W/(m·K) and a specific heat of 1800 J/(kg·K), making it a good insulator. The air pockets within the gyroid infill contribute to thermal insulation, though not as effectively as a vacuum. Approximately 254 ml of liquid nitrogen took about 56 minutes to evaporate. The insulation provided by the PLA crucible was so effective that it was possible to handle it with bare hands—though safety guidelines still recommend using cryogenic-rated gloves and safety equipment.
Practical Application
Beyond experimentation, this part has found a practical application as a structural spacer for two cryogenic steel pipes inside a vacuum chamber of a scanning electron microscope. It provides essential support to prevent the pipes from bending under the significant momentum created by a mass at the end of the lines, ensuring stability during operation.
Preliminary Observations
The initial results suggest that with careful design considerations, PLA can be surprisingly effective even in cryogenic environments. The material’s low thermal conductivity not only enhances safety by allowing manual handling but also opens the door to novel applications where insulation and lightweight design are critical. Additionally, this experiment indicates that PLA is likely gas-tight, as liquid nitrogen can penetrate only through the same pores as gaseous nitrogen—a phenomenon often demonstrated during cryogenic courses by showing how liquid nitrogen easily passes through felt or porous materials.
Let’s be curious about what other unconventional applications PLA can be used in and how we can explore the boundaries of what PLA can achieve.
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