Additive Manufacturing- Laminated Object Manufacturing & Solid Ground Curing Flashcards
1
Q
What is LOM
A
- Laminated Object Manufacturing
- Solid models are generated by laminating layers of sheet material on top of each other and laser-trim the cross sectional shape of each layer
2
Q
Laminated object manufacturing- 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 burns 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 platform raises to a height consistent with the sheet/stock thickness ready for laminating the next layer.
3
Q
Laminated object manufacturing - process characteristics
A
- Layer thickness 50-500micrometers
- 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 structure required as part remains within the block of the build material
- Parts require sanding to smooth and blend the layer edges; easily machined
- Seal and finished with paint or varnish (epoxy polymer) to prevent moisture absorption and damage
4
Q
Laminated object manufacturing - surface finish and accuracy
A
- good accuracy and resolution as any thin sheet can be used
- look and feel like the structure of wood
- physical properties can be inhomogenous due to alternating layers of material and adhesive
5
Q
Laminated object manufacturing- materials
A
any material in stock form
- paper, cellulose
- plastic
- metal
- composite fibre
6
Q
Laminated object manufacturing- applications
A
- visual models for conceptual design verifications and promotions
- patterns for sand, investment and other forms of casting
- short run moulds
- limited product testing
7
Q
pros of Laminated object manufacturing
A
- Slicing of STL mmodel after each layer provides feedback, correction during the build possible
- Larger prototypes possible (800x500x550)mm
- use of a4 paper which is readily available and inexpensive; simple and 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
8
Q
cons of Laminated object manufacturing
A
- physical properties can be inhomogeneous
- limited stability and toughness dictated by bonding strength of the glued layers
- not suitable for thin and 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 wasted
9
Q
What is SGC?
A
Solid Ground Curing
A solid model is created by selectively exposing and curing an entire layer of photosensitive polymer when shining a UV light source through a photo mask that is positioned above the surface of the liquid polymer
10
Q
Solid Ground Curing
A
- A photo mask is printing 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 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 photopolymer layer
11
Q
Solid ground curing- principle
A
- excess liquid resin is vacummed away and replaced with hot wax acting as a support structure
- top level polymer-wax surface is milled to correct flat dimensions before the next layer of resin is sprayed onto
- melting away of wax after completion of part; no post-curing required
12
Q
Solid ground curing
A
-layer thickness 50-200 micrometers
-production times for each layer 60-90sec
-uv light source >2000W
Complex system for setup and during processing
13
Q
Pros of solid ground curing
A
- entire layers can be produced quickly
- entire layers can be produced quickly (500x350x500)mm
- interrupt build process to remove incorrect layer
- no post-cure required, no internal stresses
14
Q
cons of solid ground curing
A
- complex process to setup and controll
- little development of new equipment
- one of the most expensive AM/RP techniques
- generates too much waste products
15
Q
AM Future summary
A
- new applications are developed continuously
- future areas include new materials directly deposited(metals, ceramics)
- AM for direct digital manufacturing (DDM)
