rpt_20_08 _lom
TRANSCRIPT
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Solid based rapid prototyping systems
The solid is utilized as the primary medium
to create prototyping Cubic Technologies Laminated object
Manufacturing (LOM)
Cubic technologies is exclusive manufactureof LOM rapid prototyping machine
Product : LOM 1015 PlusTM and LOM 2030HTM
Co2 Laser are used
Process consist of 3 phases:Pre-Processing, Building andPost-processing
Software Used : LOMSliceTM - which a provides menu driven
interface to perform transformations
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Phase
Pre-processingphase comprise several operations generation
of from CAD-derived STL file of the part to be generated. Sorting inputdata and creating secondary data structure.
Building: LomSlice software create a cross section of 3d model measuring exact
height of the model and slices the horizontal plane accordingly
The computer generate precise calculations, which guide thefocused laser beam to cut the cross-sectional outline, the cross-
hatches and models perimeter. The laser beam power is designed
to cut exactly the thickness of one layer of material at a time. After
perimeter is burned , everything within the models boundary is
freed from the remaining sheet.
The platform with the stack of previously formed layers descendedand new section of material advances. The platform ascends and
the heated roller laminates the material to the stack with single
reciprocal motion, thereby bonding it to the previous layer.
The vertical encoder measures the height of the stack and relays
the new height to LOMSlice, which calculate the cross section of
the next layer.
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Post-processing: Separating the part from its support
materials and finishing. The separating sequence as shown Fork lift or hammer are used to remove the part
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RPT-LOM - Specifications
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Separation of Object
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Basic Steps
Step 1. Each sheet is attached to the block, using heat and pressureto form a new layer. Sheet material is supplied from a continuous roll
on one side of the machine and taken up on the opposite side. Theheated roller provides the pressure and heat needed for lamination.
Step 2.After a layer (sheet) is deposited, a laser is traced along thecontours corresponding to the current cross section. Usually a 25 or50 watt laser is used. As in the other processes, this step starts withthe bottom cross section. Note that only the contours are scanned inthis process more efficient than the RP&M processes that require afull raster scan.
Step 3. Areas of the layer outside the contours are cross-hatched bythe laser (i.e., cut into small pieces called tiles, for removal afterfabrication).
Step 4. Steps 1-3 are repeated until the top layer of the part islaminated and cut.
Step 5. After all the layers have been laminated and cut. The resultsis a imbedded within a block of supporting material. This material isthen broken into chunks along the cross-hatching lines.
Step 6. The resulting part may then be coated with a sealant to keepout moisture.
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Laminated-Object Manufacturing
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Advantages
Wide variety of materials can be used
Fast build time
High precision
Support structure- no need additional
support structure as the part is supported byits own material that is out side the periphery
of the part built.
Postcuring: no need
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Disadvantages
Precise power adjustment is required
Fabrication of thin walls
Integrity of prototypes
Removal of supports
Applications: Visualization
Form fit and function
Manufacturing
Rapid tooling
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Applications of Rapid Prototyping
Prototype for design evaluation
Prototype for function verification
Rapid tooling processes
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Laminated Object Manufacturing (LOM)
1) Sheet of material is laminated onto existing stack-up2) Laser perforates the outline of cross section into top sheet
(cross section is NOT completely cut out- full sheet remains)
3) Edges of top sheet are trimmed to match rest of stack-up
4) Next layer is bonded and process repeats
5) When finished- have solid block with perforations separatingthe actual workpiece from extra material. Extra material
must be removed & part is sanded.
LOM modelers use paper w/ polyester adhesive. They pose no
health hazards and can be set up in offices. Further theyare comparatively inexpensive, and require no supports for
any overhangs. Unfortunately, LOM modelers also require
more post-processing work (removing part from block).
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LOM Process
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LOM Example
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Fused-Deposition Modeling
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Rapid Tooling Process
Direct tooling method
Single-reverse methods
Double reverse method
Triple reverse method
As the number of reversals increases, the durability
of a product can be improved but the product cost
increases and the precision decreases.
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Direct Tooling Method
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Single Reverse Tooling Process
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Double Reverse Tooling
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Triple Reverse Tooling
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Details of Lithography Process
Geometry input
STL format is the standard format for Rapid Prototyping
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STL format
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Advantages of STL
Easy to conversion
Wide range of input
Simple-slicing algorithm
Splitting STL models
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7/12/2013
Disadvantage of STL
Verbosity and data redundancy
Error due to approximation
Truncation error
Lack of information
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7/12/2013
Support Structure
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Selective Laser Sintering
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7/12/2013
Basic Steps
Step 1. A part cylinder is located at the height necessary for a layerof powdered material to be deposited on the cylinder to the desired
thickness. The powdered material being used for the prototype isapplied from the feed cylinder by the leveling roller.
Step 2. The layer of powder is selectively raster-scanned andheated with a laser, causing particles to adhere to each other. Thelaser scan forms the powder into the required cross section shape.Note that this step starts with the bottom cross section.
Step 3. The part cylinder is lowered by the layer thickness to permita n, layer of powder to be deposited.
Step 4. The new layer is scanned, conforming it to the shape of thenext upper cross section and adhering it to the previous layer.
Step 5. Steps 3 and 4 are repeated until the topmost layer of the
part is generated Step 6. Post-curing may be required for some materials.
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3D Printing