SHASAM
From CandyFabWiki
SHASAM is an acronym for Selective Hot Air Sintering And Melting, the name of the 3D fabrication technology employed by the CandyFab.
The printing process begins with a bed of a granular printing media that has a fairly low melting point. Using a narrow, directed, low-velocity beam of hot air, we selectively fuse together the print media, forming a two-dimensional image out of the fused grains. We then lower the bed by a small amount, add a thin flat layer of media to the top of the bed, and selectively fuse the media in the new layer, forming a two dimensional image that is also fused to any overlapping fused areas in the layer below. By repeating this process, a three-dimensional object is slowly built up. At the end of the build, the bed is raised to its original position, disinterring the fabricated model, while unused media is reclaimed for use in building the next object.
SHASAM is very much like a low-cost version of Selective Laser Sintering or Selective Laser Melting, which are commercial processes used for plastic and direct metal printing. Rather than using a high-power CO2 or YAG laser ($5k and up), we use hot air created with the help of a $10 heating element.
Trading off a laser for a heat gun gives us lower resolution but at much lower cost, and is typical of our approach to 3D fabrication. We have taken a very different approach from most other fab projects (e.g., Fab@Home and RepRap ) in that we have a comparatively large printable volume, but less need for precision and high resolution.
CandyFab is not principally designed for prototyping machine parts; it's designed for fun, for large-scale 3D illustration, for sculpting, architectural models, and other applications where resolution isn't the only important factor.
There are a number of different print media that may be suitable for use with SHASAM fabrication: many types of plastics and waxes have low melting points and are available in granular or powder form. Beyond that, there are a number of interesting foods-- chocolate chips come to mind-- that can be used with the process. However, one of the most interesting possibilities is using table sugar.
