Additives Flashcards
Two variants of 3D modelling programmes
Solid modelling- realistic product with simple calculations on volume elements
Surface modelling - for complex and realistic models, representative version only
The disadvantage of surface modelling
May not be well done if not well defined
Alternatives to designing by hand
Topology-optimisation - calculate geometry to avoid failure (only for 3D printing processes
3D scan - when parts depend on human anatomy (for complex geometry - time-consuming and difficult)
Ready-made from internet archives
Two most important file formats
STL (Standard Tessalation Language) - surface of modelled geometry is approximated by triangles
AMF (Additive Manufacturing File) - volume triangles used to approximate the volume
Process planning
- Layer thickness (roughness, print time)
- Supporting structures (printing time, material, removal)
- Orientation (more efficient printing process)
- Internal structure (subject to application)
- Print temperature and speed (depending on material)
- Generate machine code (g code, slicer software)
Process variants
- Material extrusion
- Material jetting
- Focused energy deposition
- Flat plate processes (lamination)
- Glue-jetting (binder)
- Powder bed fusion processes
- Vat polymerisation processes
Type of material extrusion
FDM
Through extrusion opening
Liquid during deposition
Needs to support the next layer
FDM: most commonly applied
Filament (colour, support element)
Also concrete, powders, metals,
dough, chocolate
Material jetting
Photopolymerisation with UV
Many colours possible
Not for thermoplastics
Direct energy deposition
Especially with metals: wire or powder
Laser, electron beam or welding arc
Benefits: fast, multiple materials
Simultaneously
Disadvantage: high surface roughness
Sheet lamination
Glue layers together
Cut contours after each layer
Only sight models / prototypes
Binder Jetting
Powder-powered layer after layer
Apply glue between layers
Prototyping (coloured glue)
Also moulds for sand casting
Good accuracy and surface
properties
Powder bed fusion
Energy source instead of glue
Melt or sint sinter powder grains
SLS: sintering, connecting grains
SLM/EBM: uniform melting
Benefits: widely applicable, strong
Cons: influence of heat
VAT polymerisation
Cure polymer with laser
Layer by layer
SLA: sinks into transparent bath
DLP: transparent wall
Disadvantage DLP: sticking bottom
Limited number of plastics
Pros of 3D printing
Extra complexity not more expensive
Short work preparation
No dies needed (time, cost)
Flexibility in variants
Location independence, user
Combining materials
Knowledge extensive
Efficient use of materials
Cons of 3D printing
Cost of machines/materials
Long production times
Number of materials is limited
Finishing
Need redesign
No standards/certification
