The University of Sydney
Intro
to
3D printing Technologies
Ben van Magill, 2019
The University of Sydney
What is 3D printing?
– 3D printing is an additive manufacturing process in which objects are built layer by layer from digital
CAD geometry.
Desired CAD model ‘Sliced’ model into finite layers
Ben van Magill, 2019
The University of Sydney
Powder based
• Polymer / metal fusion
Liquid / Resin based
• Vat polymerisation
Extrusion based
• Material extrusion
3D Printing
Ben van Magill, 2019
The University of Sydney
History
– The first patent for 3D printing technology dates
back to 1986
– Only through the increase in low cost consumer
desktop printers, it has become known to the
general public
First SLA 3D printer, 1983
FDM desktop printer,
2018
Ben van Magill, 2019
The University of Sydney
3D Printing Technologies
Selective Laser Sintering (SLS) / Direct Metal Laser Sintering (DMLS)
- Powder based
- Sintered/fused with a high-powered laser
- Powder bed provides support to print complex structures
- Strong bonding between layers (isotropic)
Ben van Magill, 2019
The University of Sydney
3D Printing Technologies
Stereo Lithography (SL/SLA)
- Resin based, cured with a UV light source
- High detail parts due to tightly focused laser (~100 microns)
- Strong bonding between layers (isotropic)
- Messy to work with
- Parts generally brittle / weaker than SLS or FDM
Ben van Magill, 2019
The University of Sydney
3D Printing Technologies
Fused Deposition Modelling (FDM)
- Extrusion based
- Lowest cost and most readily available
- Wide range of filaments available
Ben van Magill, 2019
The University of Sydney
Limitations of FDM printing
– Warping/ shrinkage from uneven temperature distributions
– Weak bonding between layers compared to in-plane (anisotropic)
Ben van Magill, 2019
Weaker Stronger
The University of Sydney
Limitations of FDM printing
– Overhangs Require support material
We can extrude ‘mid air’ between two
supporting pillars
Layer height
(eg. 0.2mm)
Overhang width max 50%
of nozzle diameter
(normally 0.2mm)
Ben van Magill, 2019
The University of Sydney
Limitations of FDM printing: Preventative measures
- Have a heated bed and/or enclosed chamber.
This brings the temperature closer the glass transition temperature of the plastic, where it is
relaxed.
- Use smart modelling techniques/ split the models in a way that focuses on what the 3D printer is
good at to suit your needs
Orientation plays a key role in this
Good strength but requires
support. Overhangs will
effect roundness
Good strength and
roundness. Requires added
manual step of bonding
Best choice for shape
(roundness), but not strength
Ben van Magill, 2019
The University of Sydney
Technology Pro Con
Selective laser sintering (SLS) - Strong bonding between layers
(isotropic)
- Requires no support structures
- Single print moving assemblies
- ‘3D nest’ parts in chamber
- Produce final functional
mechanical parts
- Expensive to buy and operate
(large footprint, high power
consumption, hard to move)
- Long warm up and cool down
times (2h warm up, cool down
50% of total build time)
Stereolithography (SLA) - Strong bonding between layers
(isotropic)
- Very high detail final parts (great
for display models or moulds)
- Messy to work with
- Parts brittle / weaker than SLS
or FDM
- All models require support to
build platform, and ~>55 degree
overhangs
Fused Deposition Modelling (FDM) - Cheap and wide range of
filaments available
- Small machine footprint
- Portable
- Capable of multi materials in
same print
- Layer bonding weaker than in-
plane strength (anisotropic)
- Warping / cracking issues
- Overhangs ~>45 degrees
require support
All 3D printing methods have issues when printing ‘large’ 100% solid parts
Ben van Magill, 2019
The University of Sydney
Extra info:
3D hubs has some great resources for learning more about 3D printing
https://www.3dhubs.com/guides/3d-printing/
Ben van Magill, 2019