3D printing has enormous potential, and its adoption is increasing but most users are still unaware of the many challenges they might have to face when adopting this technology. I’m referring to desktop 3D printer users, and some of them may feel disoriented due to the effort that goes into 3D printing parts. Filament drying is one such challenge which beginners are slightly oblivious to.
To ensure that beginners, and even some experts, have a thorough understanding of the concept of filament drying and the science behind it, we have created an ultimate guide to Filament drying, ensuring optimal 3D printing results.
Understanding Filament Moisture
Why New Filament Can Be Wet
Contrary to popular belief, even brand-new filament can contain moisture. Yes, you read it right, it can happen and due to several factors:
Manufacturing Process: With all due respect to all filament manufacturers and their efforts to produce the filaments, there is a possibility of the filament trapping moisture during the process itself. A water bath is used in at least one step of the manufacturing process. While the filament is heated after that to remove the same moisture, on humid days, the moisture may not completely evaporate before packaging.
Inadequate Desiccant: We expect a lot out of that tiny packet of silica gel, don’t we? While most of the people in general don’t really understand the use of the gel, no user has the ability to assess whether the gel is actually doing its job or not. The small packet of silica gel included in filament packaging is often insufficient for thorough drying. Interestingly, its primary purpose is to prevent additional moisture absorption during transit, rather than extracting the already existing moisture.
Environmental Factors: Most polymer filaments are hygroscopic in nature and this makes them prone to absorbing moisture from the air, especially in high-humidity environments. Once moisture is absorbed, the water molecules form strong bonds with the polymer chains in the filament. At a molecular level, these water molecules become tightly integrated within the filament’s structure and thereby will affect the printing performance of the filament.
The Impact of Humidity
Not everyone requires a filament dryer or drybox. However, if you live in an area with consistently high humidity (more than 40% inside your printing area), drying your filament and/or printing from a drybox can significantly improve print quality and outcomes. Moisture in filament can cause a variety of printing issues like:
- Reduced print quality with surface imperfections
- Weakened layer adhesion
- Inconsistent extrusion
- Bubbling or stringing during printing
The Filament Drying Process
Moisture Absorption
When exposed to humid air, filament absorbs moisture. Water molecules from the air form strong bonds with the polymer chains that comprise the filament. These water molecules become tightly integrated into the filament’s structure, which can cause a variety of printing issues mentioned in the previous section. And so this moisture needs to be extracted.
Heat Application
The first step in the drying process involves applying heat to the filament. As the temperature increases, it causes several important changes at the molecular level:
- The polymer chains in the filament begin to vibrate more vigorously.
- This increased molecular movement weakens the bonds between the water molecules and the polymer chains.
- The heat also expands the filament slightly, creating more space between the polymer chains.
These effects combined allow the water molecules, previously tightly bound to the polymer, to move more freely within the filament material.
Moisture Migration
As the drying process continues, a crucial phenomenon occurs due to the difference in moisture concentration between the filament and the surrounding air:
- The heated, dry air around the filament has a much lower moisture content than the filament itself.
- This concentration gradient creates a driving force that encourages water molecules to move towards the filament’s surface.
- The loosened bonds and increased molecular movement from the heat application facilitate this migration.
Water molecules gradually make their way from the interior of the filament to its surface, following the path of least resistance through the slightly expanded polymer structure.
Evaporation and Removal
The final stage of the drying process occurs at the filament’s surface:
- As water molecules reach the surface, they evaporate into the surrounding air.
- Proper air circulation in the drying environment is crucial at this stage, as it continuously removes the moisture-laden air and replaces it with drier air.
- This maintains the concentration gradient, ensuring the continuous movement of moisture out of the filament.
Over time, this process significantly reduces the overall moisture content of the filament, preparing it for high-quality 3D printing.
Practical Considerations for Effective Drying
While understanding the molecular process is crucial, several practical factors play a vital role in effective filament drying:
- Optimal Drying Temperature: Different filaments require specific temperature ranges for effective drying without risking thermal degradation.
- Drying Time: The time required for thorough drying varies by filament type and initial moisture content. Patience is key, as rushing the process can lead to inadequate drying.
- Air Circulation: Proper airflow is essential for carrying away evaporated moisture and maintaining the drying process’s efficiency.
- Moisture Concentration Differential: Maintaining dry air around the filament encourages continued moisture migration out of the filament.
Drying Recommendations
The above image shows the ideal drying temperature and drying time one can follow to remove the filament moisture but take these numbers with a pinch of salt and note that this temperature and time figures can significantly change on the brand of filament, the brand of dryer, the humid environment you might be living in and the method you are employing.
So, contact your filament manufacturers to get data on the filament drying temperatures and time or do the usual trial and error method to find out the ideal drying process.
Drying Methods and Equipment
Dedicated Filament Dryers
Commercial filament dryers are specifically designed for this application, providing precise temperature control and adequate air circulation. These devices are frequently the most efficient and user-friendly choice for regular filament drying.
Food Dehydrators
Many 3D printing enthusiasts repurpose food dehydrators to dry filament. While effective, ensure that the temperature is precisely controlled to avoid damaging the filament. This option may be more cost-effective than dedicated filament dryers.
DIY Solutions
Building a custom filament drying box can be both enjoyable and cost-effective for the maker community. These setups usually include a sealed container, a heat source, and a method of air circulation. While they take more effort to create, DIY solutions provide complete customisation to your specific requirements.
Avoiding Kitchen Ovens
It’s important to note that standard kitchen ovens aren’t ideal for drying filament. Their temperature control is frequently insufficiently precise, resulting in melted filament, damaged spools, and potential food contamination. Always use equipment designed or adapted for filament drying.
Maintaining Dry Filament
Once you’ve dried your filament, proper storage is key to maintaining its dry state:
- Use airtight containers or bags with desiccant to store filament when not in use.
- Consider a dry box setup for filaments in active use, especially in humid environments.
- Regularly check and replace desiccants in storage containers to ensure they remain effective.
Conclusion
Proper filament drying is a frequently overlooked but critical component of 3D printing. Understanding the science of filament moisture and implementing effective drying techniques can help you significantly improve the quality and consistency of your prints. Remember that different filaments require different drying times, so always follow the specific recommendations for your material type. You can either contact your filament manufacturers to get data on the filament drying temperatures and time or do the usual trial and error method to find out the ideal drying process.
With this information, we feel your printing experience will certainly get better. And you will always print with a dried filament and achieve the best results in your 3D printing projects.
About Manufactur3D Magazine: Manufactur3D is an online magazine on 3D printing. which publishes the latest 3D printing news, insights and analysis from all around the world. Visit our 3D Printing Education page to read more such informative articles. To stay up-to-date about the latest happenings in the 3D printing world, follow us on Facebook, LinkedIn and Twitter.