Additive Manufacturing Flashcards
What is additive manufacturing?
Process of creating a physical object from a digital model by adding successive layer of material
What are some additive manufacturing processes?
- Fused Deposition Modelling
- Stereolithography
- Selective Laser Sintering
- Contour Crafting
- D-shape
Why is Additive manufacturing important in space?
- Reduction of waste
- Spare parts
- Easier planning of components
- Supports unexpected applications
What are the steps for creating a 3D print?
- CAD design
- Convert file type
- Slicing
- Printing
- Post processing
What are some defects of additive manufacturing?
- Warping
- Layer separation
- Porosity
- Residual stresses
- Incomplete melting
- Surface roughness
What are the pros and cons of using concrete for Additive Manufacturing?
Pros:
- Not sensitive to regolith composition
- Lower temperature process
- Can be used as slurry for contour crafting
Cons:
- Sensitive to curing conditions
- Sulfur concrete sensitive to thermal cycling
What is D-shape technology?
Binder is sprayed on sand/regolith
What are the pros and cons of Polymers for additive manufacturing?
Pros:
- Relatively low temperature
- Easy extrusion
Cons:
- Low durability
- Recovery of Polymers
What are geopolymers?
Made of mixture of aluminosilcate powder and alkaline solution.
What are the pros and cons of Geopolymers for additive manufacturing?
Pros:
- Controllable setting and hardening
- Low temperature process
- Not sensitive to regolith composition
Cons:
- Availability of alkaline species
- Availability of superplasticizers
What is sintering?
Binding of particles in contact using energy
What IS selective laser sintering?
- Classic SLS powder printing with Co2 laser
What are the pros and cons of laser sintering?
Pros:
- Only uses regolith
Cons:
- Larger particles need to be removed
- Unsure applications
What are the pros and cons of large laser melting?
Pros:
-Tick solid glass from just regolith
- Not sensitive to regolith composition
Cons:
- 10 kW laser
- Cooling and annealing unsure
- Cracks when 3D printing
What is warping?
The corners and edges of a printed part can curl and lift from the build plate due to temperature differences during printing
What is Layer Seperation?
The layers of a printed part can separate from one another, particularly if the part has a large overhang or if adhesion is poor
What is porosity?
3D printed parts from powder beds can have tiny air pockets within their structures due to the heating and cooling process, reducing the mechanical strength of the part.
What are residual stresses?
The rapid heating and cooling of fused powder can lead to residual stresses in the part, which can cause warping or cracking.
What is incomplete melting?
If the laser (or electron beam) does not completely melt the powder, the resulting part can have weak points, porosity, or structural defects.
What is Surface Roughness?
The surface of a 3D printed part can be rough, requiring additional postprocessing steps such as sanding or polishing.
What are the two types of sintering?
- Solid State Sintering
- Liquid Phase Sintering
What are the pros and cons of Solar Sintering?
Pros:
- Only uses regolith and sunlight
- Suitable for a large structure
Cons:
- Difficult layer deposition
- Limited Mechanical Property
- Resistance to rocket exhaust uncertain
What are 2 forms of sintering?
- Solid-state sintering (atoms of particles in contact rearrange, leads to neck formation and densification)
- Liquid phase sintering (Particles with lowest melting point act as lubricant and binder)
What are the pros and cons of other melting techniques?
+ Thick and solid glass obtained from solely lunar regolith
+ Not sensitive to regolith composition or PSD
- Power
- Cooling of glassy material, annealing possibility TBC
- 3D printing capability TBC
