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