Additive Manufacturing Flashcards
Process controllers
usually some type of digital computer, often a PLC, with the core feature being the mircro-processor
Interface devices
allow process to be connected to the computer controller.
Actuator
Device that converts control signals into a physical action (usually a change in a process input parameter)
Sensor
Device that converts a physical stimulus or variable into a more convenient form (iue.e., temp, force, pressure etc. to electrical voltage)
extrusion-based AM
loading material -> liquification -> application of pressure to move through nozzle -> extrusion -> plots according to predefined path and bonds material to itself or secondary build materials
Uses thermoplastics like ABS, PLA, thermoplastic polyerurethane, HIPS, PA (nylon)
Pros and cons of extrusion-based AM
Pros: cost-effective, short lead times, great for prototypes
Cons: slow speeds, circular nozzle makes difficult to resolve sharp and intricate corners, poor resolution, susceptible to warpage, porosity issues
SLA
Stereolithography: Uses UV lasers to selectively cure polymer resins
Vat Polymerization and pros and cons
Uses liquid, radiation curable resins, or photopolymers to cure layers one on top of the other
Pros: accurate, smooth finish, speciality resins available
Cons: Products are brittle, photosensitive, support structures leave marks
DLP
Digital light processing: Uses digital projectors as a UV light sources to cure layers
LCD
Liquid crystal display: Uses LCD display module to project light patterns to cure layers
Binder-jetting AM
Uses powders and liquid adhesives create each layer. Binder is deposited corresponding to cross sectional layers. Loose powders serve as support and are removed after building. Can sinter part after to strengthen.
Material jetting/printing and pros and cons
Melts the starting material and shoots small droplets from the nozzle to cold-weld onto substrate or previous layer.
Pros: Smooth parts, accurate, isotropic mechanical and thermal properties, multi-material capabilities
Cons: Not very good mechanical properties, photosensitive, expensive
Binder jetting pros and cons
Pros: metal parts and full color prototypes, large and complex geometries, no support structures needed
Cons: Accuracies and tolerances hard to predict, shrinkage during sintering, porosities, green-state parts very brittle
Powder bed fusion
A moving heat source sinters or melts powder particles selectively according to predetermined area. After each layer, piece is moved down to add new layer.
What are the 3 types of Powder bed fusion?
SLS (Selective Laser Sintering): laser selectively sinters particles of polymer
LPBF (Laser Powder Bed Fusion) or SLM (Selective Laser Melting): More powerful fiber lasers induce full melting followed by fusion
EB-PBF (Electron Beam Powder bed fusion): Electron beam uses magnetic optic system to collide with metal particles, converting their kinetic energy into heat
