Which process is used to harden heat-fusible powders in rapid prototyping?

Selective Laser Sintering (SLS) is the correct process used to harden heat-fusible powders in rapid prototyping. This technique utilizes a laser to selectively fuse powder material, layer by layer, to create a solid object. The laser selectively targets specific areas of the powder bed, causing the particles to melt and adhere to one another, forming a solid structure that reflects the intended design.

This process is particularly advantageous because it allows for the creation of complex shapes and geometries that may be difficult or impossible to achieve with traditional manufacturing methods. It also permits the use of a variety of materials, including plastics and metals, which can expand its applications beyond just prototyping to include small production runs and customized parts.

In contrast, other methods like stereolithography primarily use liquid resins and a light source for curing, while laminated object manufacturing layers sheets of material and bonds them together, and fused deposition modeling involves extruding thermoplastic filaments rather than powder. Each of these processes operates on different principles and materials, which is why selective laser sintering stands out for its specific application with heat-fusible powders.