What is the role of a heated bed in FDM printing?

In Fused Deposition Modeling (FDM) printing, a heated bed plays a critical role in the process by helping to prevent warping of printed layers. When a thermoplastic material is extruded from the nozzle, it cools as it is laid down on the print bed. If the bed is not heated, the material can cool too quickly, causing the printed layers to contract unevenly and leading to warping or detachment from the bed.

Having a heated bed maintains a more consistent temperature, helping to keep the initial layers of the print warm. This reduces thermal stress and minimizes the risk of warping, especially with materials that have a high tendency to shrink as they cool, such as ABS. Therefore, the heated bed ensures better adhesion of the print to the build surface and contributes to an overall higher quality and successful print outcome.