Drying and storage of 3D Printing Polymers
Keep Your 3D Filament Dry
3D prints may partially or completely fail if moisture ingress has occurred in the filament used. Without appropriate dry storage procedures in place, at some point problems during printing will almost certainly arise due to humidity. Filaments absorb water molecules from the ambient air in a natural process known as hygroscopy. This absorption can occur in just a few hours if filaments are left exposed to the atmosphere. Nylon filaments are most at risk. The situation is even worse with specialty filament like PVA which is extremely hygroscopic and needs special storage conditions to maintain its usefulness.
3D printing problems typically caused by moisture absorption are:
- increased brittleness
- diameter augmentation
- filament bubbling
- filament degradation
The degree to which these problems arise depends on the type of filament. For instance, PET is not dramatically affected by ambient air moisture while Nylon will saturate quite quickly and may pose problems printing if not stored properly.
If the filament spools have already been exposed to the air over a certain time, they are likely to already be saturated with moisture and a drying process may be required first.
There are a couple of solutions and the choice will ultimately depend on the volume of product to be stored and available budget.
The most sophisticated solution is to dry and store using a dry cabinet. Totech XSD desiccant cabinets deliver outstanding performance for floor life reset of moisture sensitive 3D printing materials, components and PCB’s, as well as coatings, sprays, molding pellets and moisture absorbent materials of all kinds.
The advanced technology of XSD desiccant cabinets delivers a process combining ultra low humidity (<0.5%) and mild temperatures (40-60°C) for moisture removal and safe long-term storage. These temperatures are well within the “glass transition temperature” of even the least heat resistant polymers. Higher temperatures will affect the filament properties changing them from hard and brittle to soft, molten and unusable.
For a more budget friendly option, but nothing like as sophisticated, Moisture Barrier Bags may be the solution. MBBs (sometimes called Vapor Barrier Bags or vacuum bags) are increasingly used to pack moisture sensitive devices and materials for long term storage and transport.
They are made from multiple layers of plastic and aluminium that control moisture vapor leakage and will store filament spools in an air-free environment so that they cannot absorb additional moisture from the ambient air. Filaments need to be dry before vacuum bagging- MBB storage will otherwise serve little purpose. Standardized packets of desiccant drying agents are used to absorb any residual moisture from the air left inside moisture barrier bag after it has been sealed. A Humidity Indicator Card (HIC) should also be placed inside the bag in order to confirm that that the spool has remained in a safe state during storage.