Additive Manufacturing V Flashcards
1
Q
Laminated Object Manufacturing - LOM
A
- Solid models are generated by laminating layers of sheet material on top of each other & laser-trim the cross-sectional shape of each layer.
- Category - Sheet Lamination
2
Q
LOM - Method
A
- Paper or plastic sheet material with a heat-activated glue on one side is bonded to the build platform by applying pressure using a heated roller.
- A focused CO2 laser byrns the outline of the first layer into the paper and then criss-crosses the excess area.
- The platform lowers and a feeder/collector mechanism advances new sheet material onto the build platform.
- The paltform raises to a height consistent with the sheet/stock thickness ready for laminating the next layer.
3
Q
LOM - Process Characteristics
A
- Layer (stock) thickness 50-500 (micrometres)
- Cutting depth is controlled to cut top layer only.
- Slicing the 3D model is performed after completing each layer to account for actual thickness of sheet stock.
- Process generates considerable smoke which requires extraction
- No specialised support required as part remains within the block of the build material.
4
Q
LOM _ Materials
A
-Virtually any material in stock form:
- Paper, cellulose
- Plastic
- Metal
- Composite fibre
5
Q
LOM - Applications
A
- Visual models for conceptual design verifications & promotions.
- Patterns for sand, investment & other forms of casting.
- Short run moulds
- Limited product testing
6
Q
LOM - Advantages
A
- Slicing of STL model after each layer provides feedback; correction during the build possible.
- Large prototypes possible (800x500x550)mm
- Use of A4 paper which is readily available and inexpensive; simple & inexpensive setup.
- No extra support structure required.
- Dimensional accurate parts.
- Fast processing time.
- Low cost due to a variety of inexpensive organic and inorganic material.
7
Q
LOM - Limitations
A
- Physical properties can be inhomogeneous
- Limited stability and toughness dictated by bonding strength of glued layers.
- Not suitable for thin & intricate design contours in z-direction
- Not suitable for hollow structure with closed surfaces.
- Removal of the support structure can be difficult and time consuming.
- Majority of the material consumed is waste.
8
Q
Solid Ground Curing - SGC
A
- A solid model is created by selectively exposing & curing an entire layer of photosensitive polymer when shining a UV light source through a phot mask that is positioned above the surface of the liquid polymer.
- Category - VAT Photopolymerisation
9
Q
SGC - Method
A
- A photo mask is printed on a glass plate using an electrostatic process (similar to photocopying and laser printing) charging a negative image of the layer onto the surface.
- Thin layer of liquid photopolymer is distributed over the surface of the work platform.
- Photo mask is positioned above the polymer surface, exposed to a high powered UV light source which cures the desired cross-section of the photo-polymer layer.
10
Q
SGC - Process Characteristics
A
- Layer thickness 50-200 micrometres
- Production times for each layer 60-90sec
- Ultraviolet light source > 2,000W
- Very complex system for setup and during processing.
11
Q
SGC - Advantages
A
- Entire layers can be produced quickly
- Large prototypes possible (500x350x500)mm
- Interrupt build process to remove incorrect layer
- No post-cure required, no internal stresses.
12
Q
SGC - Limitations
A
- Complex process to setup & control
- Little development of new equipment.
- One of the most expensive AM/RP techniques.
- Generates too much waste products
13
Q
Additive Manufacturing -Summary
A
- Future:
- New applications are developed continuously
- Future areas include new materials directly deposited.
- Additive Manufacturing for direct digital manufacturing..
- Limitations:
- Materials - growing range but will remain limited range with high costs
- Accuracy & surface roughness - often tolerance limit.
- Equipment cost - expensive often with poor output per £ investment.
