University Course "Micro and nano systems" for Master Degree in Biomedical Engineering at University of Pisa. Topic: Fused deposition modelling

1. Fused deposition
Modelling
carmelo.demaria@centropiaggio.unipi.it

2. + Question #1 14/10/2015

3. + Question #2 14/10/2015
Indicates which of the following material has the lower
working temperature (for FDM technology)

4. + Question #3 14/10/2015
T <=100
100<T<=150150<T<=200
200<T<=250
250<T<=300
T > 300
Indicate the working temperature of ABS (FDM technology)

5. + Fused deposition modelling (FDM)
• FDM is the second most widely used rapid prototyping
technology, after stereolithography.
• A plastic filament is unwound from a coil and supplies material
to an extrusion nozzle. The nozzle is heated to melt the plastic
and has a mechanism which allows the flow of the melted plastic
to be turned on and off.
• The nozzle is mounted to a mechanical stage which can be
moved in both horizontal and vertical directions.
• As the nozzle is moved over the table in the required geometry,
it deposits a thin bead of extruded plastic to form each layer.
• The plastic hardens immediately after being squirted from the
nozzle and bonds to the layer below. The entire system is
contained within a chamber which is held at a temperature just
below the melting point of the plastic.

6. + Fused deposition modelling

7. OPEN 3D PRINTING
The Rep Rap Project

8. + Open 3D printing: the RepRap
project
• RepRap is first general-purpose self-replicating
manufacturing machine.
• RepRap takes the form of a free desktop 3D printer
capable of printing plastic objects.
• Since many parts of RepRap are made from plastic
and RepRap prints those parts, RepRap self-
replicates by making a kit of itself - a kit that
anyone can assemble given time and materials.

9. + The RepRap Project

10. + The RepRap Project

11. + The RepRap Project

12. + The RepRap Project

13. + How many RepRaps?

14. MATERIALS FOR FDM
With basics of polymer rheology

15. + Materials
• FFF = Fused Filament Fabrication
• Filament: fine diameter plastic that exits
from an extruder (some may refer to the
plastic feed stock as filament as well)
• Typically, the diameter of the filament varies
between 1 mm and 3mm
• The standard extruder produces filament
using high pressure and heat to force
molten plastic thru a very tiny hole.

16. + Materials
• “Standard” materials:
– Poly-Lactic-Acid (PLA) (soft and hard)
– Acrylonitril-Butadiene-Stiren (ABS)
• “Experimental” materials:
– Nylon
– Polycarbonate (PC)
– Poly vinyl alcohol (PVA)
– Conductive (carbon and
graphen loaded materials)
– Metallic loaded plastics

17. +
Rheology

18. + Variabili che influenzano la reologia
dei polimeri
• Variabili reologiche:
– deformazione
– velocità di deformazione
• Variabili strutturali-compositive:
– peso molecolare medio
– polidispersità (Mw/Mn)
– architettura molecolare (es: presenza di ramificazioni)
– presenza di una fase dispersa (quantità, dimensionale media
e distribuzione, forma)
– contenuto di additivi (es: plastificanti)
• Variabili termodinamiche:
– pressione
– temperatura

19. + Curva di flusso (viscosità in regime
stazionario): comportamento shear thinningcurva di flusso (viscosità in regime stazionario):
comportamento shear thinning
10
-3
10
-2
10
-1
10
0
10
1
10
2
10
3
10
4
10
510
1
10
2
10
3
10
4
dati piatto-cono
dati capillare
best fit eq. Cross
zona di
power law
zona
newtoniana
h
0 = 7.0
l = 0.14
n = 0.79
Polistirene
Mw=170.000
T=200°C
Shear rate (s-1
)
Viscosità(Pa·s)
bassi De alti De
equazione
di Cross
n
0
)(1 gl
h
h
&+
=
)( 0hh <<¥

20. + Viscosità e condizioni tipiche di
processo

21. + Effetto del peso molecolare
Effetto del peso molecolare
10
-3
10
-2
10
-1
10
0
10
1
10
2
10
3
10
4
10
5
10
1
10
2
10
3
10
4
10
5
Polistirene
Mw
=170.000
h0
=7.000 Pa·s
Polistirene
Mw
=280.000
h0
=40.000 Pa·s
T=200°C
Shear rate (s
-1
)
Viscosità(Pa·s)
4.3
w0 MµhUna caratteristica distintiva dei polimeri
ad alto peso molecolare:
Seminario di Reologia, Università di Padova, 2008

22. + Effetto della polidispersità

23. + Fenomeni dovuti
all’elasticità del fuso

24. + Il die swell del polistirene

25. + Altra manifestazione dell’elasticità del fuso:
la pressione di ingresso

26. + La melt fracture aumenta
all’aumentare della shear rate

27. + Comportamento reologico
di sistemi polimerici multifasici
• Alcuni tipi di sistemi multifase:
– polimeri rinforzati con cariche minerali o fibre
– polimeri tenacizzati con fase gommosa dispersa
– blend immiscibili
– copolimeri a blocchi
– schiume
• Variabili che influenzano la reologia di sistemi multifase:
– quantità di fase dispersa
– media e distribuzione delle dimensioni particelle
– fattore di forma delle particelle
– distanza inter-particellare media
– deformabilità della fase dispersa

28. + Un importante effetto della fase
dispersa: lo yield stress

29. + polimeri con fase gommosa
(reticolata) dispersa

30. A LOOK INTO SLICING PARAMETERS

31. + Cura

32. + Slic3r

33. + Stratasys Catalyst

34. + Stratasys Catalyst