ADDITIVE MANUFACTURING ANSWERS AND
QUESTIONS SET A+
✔✔Computer- Aided Design (CAD) - ✔✔solid modeling is preferred over surface
modeling; ensure that there is volume so fully enclosed surfaces;
✔✔What are surface models described by? (CAD) - ✔✔boundary curves- difficult to
connect together; gaps make it difficult to process by AM machines
✔✔STL CAD file format - ✔✔uses triangles to describe the surfaces to be built; each
triangle is described by 3 points and a vector that is normal to the facet that indicates
the outward side of the triangle;
✔✔STL drawbacks - ✔✔only describes shape and nothing else; complex shapes can
make the file large and cumbersome; it cannot take advantage of the multi-material
printing
✔✔AMF - ✔✔developed by Hod Lopson; XML based Open standard to describe objects
meant for AM; describes shape and composition; contains support for color, materials,
texture and mesostructures
✔✔What is the problem with classifying AM processes based on baseline technologies
or raw material input? - ✔✔these tend to lump together odd combination of processes;
they also separate some processes that produce similar results
✔✔Classification by Pham - ✔✔2d approach: 1. the "state and kind" of raw material
employed 2. the way layers are constructed
✔✔Vector scanned - ✔✔outline (shells or contour layers)
✔✔Raster pattern - ✔✔fill pattern (infill and may be defined as a percentage)
QUESTIONS SET A+
✔✔Computer- Aided Design (CAD) - ✔✔solid modeling is preferred over surface
modeling; ensure that there is volume so fully enclosed surfaces;
✔✔What are surface models described by? (CAD) - ✔✔boundary curves- difficult to
connect together; gaps make it difficult to process by AM machines
✔✔STL CAD file format - ✔✔uses triangles to describe the surfaces to be built; each
triangle is described by 3 points and a vector that is normal to the facet that indicates
the outward side of the triangle;
✔✔STL drawbacks - ✔✔only describes shape and nothing else; complex shapes can
make the file large and cumbersome; it cannot take advantage of the multi-material
printing
✔✔AMF - ✔✔developed by Hod Lopson; XML based Open standard to describe objects
meant for AM; describes shape and composition; contains support for color, materials,
texture and mesostructures
✔✔What is the problem with classifying AM processes based on baseline technologies
or raw material input? - ✔✔these tend to lump together odd combination of processes;
they also separate some processes that produce similar results
✔✔Classification by Pham - ✔✔2d approach: 1. the "state and kind" of raw material
employed 2. the way layers are constructed
✔✔Vector scanned - ✔✔outline (shells or contour layers)
✔✔Raster pattern - ✔✔fill pattern (infill and may be defined as a percentage)
