1. DESIGN FOR
ADDITIVE
MANUFACTURING
PARTICULARITIES TO BE CONSIDERED
WHEN PREPARING PARTS FOR BEING
PRINTED ON AN ULTIMAKER FDM PRINTER
Greta D’Angelo
Martí Bertran
Thomas J. Howard

2. AGENDA
1. Introduction on FDM and AM
2. Geometrical constraints
3. Support structures
• Avoiding support structures
• Working with support structures
4. Hollowed parts and infill
5. Printing text
6. Designing mechanisms
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3. FUSED DEPOSITION
MODELLING
• Additive Manufacturing (AM)
technologies build parts by
overlapping layers of
material
• Extrusion of melted material
through a nozzle on a build
plate
• Cartesian coordinates
• Tolerance (in vertical
direction) is determined by
the diameter of the nozzle
• Examples:
Stratasys, RepRap, Ultimake
r
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4. WORKFLOW
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Design a part Export to STL Check STL
• CAD program • All packages can • Netfabb
do it
6 5 4
Start printing! Upload Gcode Slice and
• Ultimaker’s to printer generate Gcode
controller • SD card • Cura
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5. MATERIAL PROPERTIES
• Ultimaker uses 3mm PLA
PLA filament Polymer
• Biodegradable Physical property
thermoplastic Specific Gravity [g/cm3] 1,25
Melt Index [g/10min]
• Highly anisotropic (190º/2,16kg)
4-8
mechanical properties
• Several colors available
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6. GEOMETRICAL
CONSTRAINTS
Minimum Wall thickness:
• Vertical and tilted walls:
• 2mm and above. Recommended
• Horizontal walls:
• 1mm and above is correct
Definition  0,5mm minimum details noticed
Accuracy  0,3% (min +/-0,3mm)
Avoid warping  Large horizontal and thick surfaces are
likely to warp, skip using them if you can.
Overall maximum dimensions  150*150*150 mm (x*y*z)
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7. FACING GEOMETRICAL
CONSTRAINTS
• Scale parts
• After scaling check that your part meets the geometrical
constraints
• Notice that wall thicknesses will be scaled down as well, and
may not meet the requirements
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8. SUPPORT STRUCTURES
• Support structures are
features added below
part areas where
there’s nothing
• They prevent layers to
collapse during it’s
build up and allow
part manufacturability
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9. AVOIDING SUPPORT
STRUCTURES: PART ORIENTATION
• Part orientation is a key
factor to achieve a good
print
• In many cases we can
avoid or at least reduce
the amount of supports
required
• Resolution is better in the
z-axis faces (vertical) than
XY (horizontal) 
stepping
• Mechanical properties are
better in the XY plane
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10. PART ORIENTATION
Smooth
surfaces
Staircase effect
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11. AVOIDING SUPPORT STRUCTURES:
SPLITTING PARTS
• Splitting parts is a good way
to avoid using supports
• Can be done after exporting
the CAD to STL by using
Netfabb
• To use in extreme causes
because:
• We’ll have to glue all the
parts after the print
• Tolerances will not be the
same
• We’ll see partition lines in
our part
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12. AVOIDING SUPPORT
STRUCTURES: MODIFY
OVERHANGING SURFACE
• The printer is able to print
overhanging surfaces
without support structures
from a minimum angle
α (>30º)
• We must do the
modifications before
exporting the STL file
• Small projections from the
walls (<1mm) can be
printed without problems
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13. AVOIDING SUPPORT
STRUCTURES: MODIFY
OVERHANGING SURFACE
• Cura Software shows which surfaces
needs support structures (<30º)
Support structures
required here
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14. AVOIDING SUPPORT
STRUCTURES: BRIDGES
• The printer is able to Bridge
print flat surfaces
without supports
between two walls
• Max distance between
walls: 20mm
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15. AVOIDING SUPPORT
STRUCTURES: BRIDGES
Small holes
doesn’t require
changes
Bridge
Modified hole
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16. WORKING WITH
SUPPORT STRUCTURES
• Accessibility: We must be
able to remove SS easily
• Scaring: Avoid using them
in part characteristic
surfaces  SS can
damage the finishing of
these surfaces and also
the tolerances
• Avoid using SS below thin
walls or slender and
fragile parts, they can
break easily while
removing them
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17. HOLLOWED PARTS AND
INFILL
• Hollow can be achieved when gcode is generated, by
changing parameters of Cura
• We can also choose how much infill (%) we want inside the
part, by default we use between 30% and 40%
• Design Tip: design always solid parts
Infill
Perimeters
Gcode Cura View
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18. HOLLOWED PARTS AND
INFILL
By reducing the infill:
• Build time decreases
• Used material decreases
• It helps to avoid warping
• Strength doesn’t decreases
that much
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19. PRINTING TEXT
• Text in vertical faces will be
more visible and accurate
• If it’s not possible, the text at
the bottom of the part (the
face that sticks to the building
platform), must be engraved.
• In the top face of the part, text
can be either
engraved/embossed
• It should be at least 0,8mm
high and 0,8mm wide to be
visible.
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20. PRINTING TEXT
Vertical embossed text
Horizontal engraved text
Vertical engraved text
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21. DESIGNING
MECHANISMS
Joints clearance:
• Design adjustments with a gap of
more than 0,3mm between mobile
parts
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22. DESIGNING
MECHANISMS
Part orientation
• Try to print the areas of parts that has to fit
each other in the same orientation (different
orientations could have different
deviations/tolerances)
Integrated nut holders  embossed is better
than engraved!
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23. QUESTIONS?
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