Layered Manufacturing
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Transcript Layered Manufacturing
Layered Manufacturing
How can we make physical form?
Additive
Subtractive
Deformation
Additive Process
Add materials bit by bit
Less material wastage
Usually need a mould
Casting
Subtractive Process
Remove un-needed material from stock
Waste material
Usually need only cutting tools
Milling, Sculpting
Deformation Process
Deform stock material
Less material wastage
Limited form, need many different tools
Bending, kneading
Sometimes called Net-Shape
Manufacturing
Layered Manufacturing
Additive process in nature
No mould required
No special tools
One machine, unlimited forms
Basic process
Basic process
Prepare CAD model
Slice model virtually into layers
Produce the bottom most (or top most)
layer according to the layer profile
On top of (or beneath) the produced layer,
add subsequent layer
Loop until completion
Freedom of LM
Undercut
Hollow
Jig and fixture not required
Advantage of LM
Reduce operator intervention
Easy to learn
Time and cost only related to size, not
complexity
Disadvantage of LM
Time and cost only related to size, not
complexity
Limited choice of material
Double approximation of the form, first
during polygonization and then by slicing
Common use of LM
Rapid Prototyping
One-of-a-kind manufacturing
Art sculpting
Medical modelling
Architectural modelling
Shape implications in LM
Overhang
Cliffs
Holes
Slicing errors
Exercise
Rapid prototyping process
Polygon model creation
Model verification
Pre-processing
Orienting and positioning
Support generation (optional)
Slicing
Building
Post-processing
Rapid prototyping process
Data input
Almost all RP systems rely on STL
A polygon model format
ASCII and Binary
With normal vectors
Implicit unit
Can be generated from all major
applications
One file can contain multiple components
Data Input
An ASCII STL file
Model verification
LM can deal with only non-manifold
polygon models
Check for ‘leakage’
Check for naked edges
Check for holes
Check for reversed facets
Check for model obscurities
Model obscurities
Crossed facets
Overlapping
facets
Degenerated
facets
Source of manifold errors
LM Errors caused by bad STL
Delaminate due to
double facets
Reversed normals
Ill-behaved CAD
translators
Verification applications
Major polygon modelling applications
RapidForm, Surfacer, GeoMagics, etc.
Specific STL applciatons
Magics
SolidViews
Function of verification applications
Check and repair model errors
Rotate and section model to facilitate error
correction
Merge and separate components
Move, rotate, and scale models
Checking dimensions
Advanced editing
Advanced editing
Fill holes by adding facets
Add draft angle
Shelling and hollowing
Smoothing and re-sampling
Pre-processing
Done by equipment specific applications
Move, rotate, and scale models
Some contain basic STL repair functions
Some contain support generation and edit
functions
Slicing STL and generating equipment
control code
Supports
Position and size of model
Machine specific, usually lower left corner
as the origin
Position and size can be verify in preprocessing application
Built-specific errors (beam width, thread
width, growth, etc.) compensated by
application
Shrinkage, form and fit, etc. compensated
by operators
Building process
SLA
Clear Epoxy
Non-critical products
EOS
Nylon / Steel
‘Usable’ products
FDM
ABS
3DP
Plaster
Functional
prototypes
Concept prototypes
Thermojet Wax
Concept prototypes
Post-processing
Draining and rinsing
Support removal
Post-curing and heat-treating
Surface finishing