What is the purpose of a "raft" in FDM printing?

The purpose of a "raft" in Fused Deposition Modelling (FDM) printing is to improve adhesion and stabilize the print during the printing process. A raft is a printed layer that sits between the printing surface and the actual model. It is particularly beneficial for prints that have a small contact area with the build plate, which can lead to warping or detachment as the material cools.

By using a raft, the first layers of the print have a larger surface area that allows for better bonding with the build plate. This increased adhesion helps to prevent issues such as shifting or curling at the edges of the print. Additionally, the raft can create a more uniform foundation that enhances the overall stability of the printed part during the printing process. This makes it particularly useful for materials that are prone to warping, ensuring that the final product has better dimensional accuracy and surface finish.

In contrast to adding decorative features, reducing weight, or enabling simultaneous printing of multiple parts, the primary and most significant role of a raft is clearly related to enhancing the printing surface characteristics essential for successful builds.