bioplasticsMAGAZINE_1406

3D printing
What is 3D printing?
Challenges for making bioplastics 3D printable
Christian Bonten is the Chairholder and the director of
the Institut für Kunststofftechnik (Institute for Plastics
Engineering) in Stuttgart, Germany, partner in the
BioFabNet project (cf. p. 18) , and here he explains the technology:
As soon as you need just one of a kind, or a prototype, it is
worth using an additive manufacturing process, which does
not need a costly mould like for instance injection moulding.
There are different kinds of processes (see Fig. 1), that can all
be covered by the umbrella term 3D printing.
Commonly, all of these additive manufacturing processes
use flowable materials or materials in powder form and build
up the final products in the form of layers. Here, layer by
layer is deposited on, and connected to, the former layers in
different ways. The 3D CAD model is converted into a layer
model (STL format) and then forwarded to the controller of
the additive process machine. The final part is always stepped
and its surface is not smooth (Fig. 2).
The original 3D printing is just one kind of these additive
manufacturing processes. In this original process, a layer of
powder is brought onto a platform where a printing head runs
over the layer and glues the powder selectively. It works rather
similar to ink jet technology.
Today, another process, the Fused Deposition Modelling
(FDM), is used widely – even in private households – and
hence stands synonymously for the additive manufacturing
processes in general. In the FDM process, a heated nozzle
delivers a melt strand linearly on a platform (Fig. 3). This
thermoplastic strand solidifies after cooling and the next melt
strand can be laid down on top of it.
Solid
Liquid
Gaseous
Filament
Fusing /
solidifying
Solidify by
binder
Powder
Fusing /
solidifying
Blanking /
glue
Film
Blanking /
polymerisation
Polymerisation
Chemical
reaction
Process:
lay down of a melt strand
filament
Fused
deposition
modeling
(FDM)
3D-
Printing
(3DP)
Selektive
laser
sintering
(SLS)
Laminated
object
manufacturing
(LOM)
Solid
polymerisation
(SFP)
Stereolithography
(SLA)
Laser
chemical
vapor
deposition
(LCVD)
contact heating
Fig. 1: Different 3D printing processes at a glance
(source: 3D Printing, Carl Hanser Publishers)
1 2
prototype
nozzle
linewise
application
supporting structure
base plate
3
4
Fig. 3: Principle of the FDM process
(Source: Fig. 5.66 in Kunststofftechnik, Carl Hanser Publishers)
Layered
construction
Fig. 2: Principal cycle of additive manufacturing processes (Source:
Fig. 5.61 in Kunststofftechnik, Carl Hanser Publishers)
This QR-Code (or the short-link
bit.ly/1uiDvXh) connects to a short
video-clip on the IKT-Youtube-channel
that demonstrates the FDM process
16 bioplastics MAGAZINE [06/14] Vol. 9