How does powder bed fusion build part layers?

The correct choice highlights that powder bed fusion operates through the application of focused thermal energy to selectively fuse powdered build materials. This technique involves spreading a thin layer of metal or polymer powder across a build platform. Once the layer is applied, a laser or electron beam is directed at specific areas of the powder, causing those particles to melt and fuse together. After the layer has been completed and solidified, the build platform is lowered, and another layer of powder is applied on top, repeating the process until the entire part is built.

This method is crucial for achieving high precision and complex geometries in additive manufacturing, which are difficult to achieve with traditional machining methods. The ability to control the fusion at the particle level allows for intricate designs and often results in parts with excellent mechanical properties.

The other options don't accurately describe the powder bed fusion process: stacking solid sheets of material suggests a traditional layering technique rather than fusion of powder; layering molten material implies a different process commonly associated with other additive manufacturing methods like direct energy deposition; and using glue to bind loose powders is not representative of the thermal energy-driven fusion process that characterizes powder bed fusion.