Closed-cell self-expanding foam, commonly known as spray foam, is a versatile material typically used in construction, but it’s now being applied in the realm of 3D printing. In a recent YouTube video by Alex, he explores the potential of using this foam to fill the internal voids of 3D printed objects, particularly aiding in making boats more buoyant and keeping sensitive electronics dry.
It’s widely recognized that 3D printed objects created with FDM (Fused Deposition Modeling) printers are not watertight. The printing process often allows for small gaps between layers that can let moisture in. This is where spray foam proves beneficial, as it offers a watertight seal. Alex’s experiments also investigate how this foam affects the structural integrity of prints and how it enhances insulating properties.
For the experiments, test prints were designed with a port for foam injection and necessary pressure relief holes. These prints required a 24-hour curing period after filling. Initial findings indicated that the foam must be prepped with water to activate its chemical curing process inside the print. Additionally, it’s crucial to create enough pressure relief holes for larger prints to prevent potential structural failures due to the expanding foam.
Results from the tests showed that while there was some water absorption detected, particularly in a PETG print, no samples filled with water after being submerged for 28 hours. The tensile strength remained unchanged; however, the compression resistance increased significantly, reflecting a 25% to 70% enhancement against buckling.
A comparative thermal test demonstrated that a typical FDM printed box melted ice in under six hours, whereas the box filled with foam took nearly eight hours to do the same. This difference underscores the thermal insulation benefits that spray foam provides.
In summary, incorporating self-expanding foam into 3D printed parts is a smart choice for those looking to enhance waterproofing, add structural strength, or improve thermal insulation beyond what standard FDM infill patterns can offer.