2.1 Printing
Equipment
1. Ultimaker 2 printer (Ultimaker).
2. Polylactic acid filament (see Note 1).
2.2 Characterization
Equipment
1. Universal tensile tester equipped with compression plates.
2. Optical microscope equipped with a digital camera.
3 Methods
3.1 G-Code
Instructions
The printer-head movements are controlled by the G-code—a
programming language originally developed to control the tool
path of CNC machines. The commands starting with “G” instruct
the machine as to what the tool path must obey:
G10: the machine retracts the filaments from the printing head and
it stops extruding. This command can be followed by the
option S0 for “short retract” or S1 for “long retract.”
G11: the machine pushes the filament into the printing head and it
starts extruding.
G1: the machine linearly moves to the specified point while extruding the melted material. This command is followed by five
parameters F, X, Y, Z, and E. The printing head moves to the
point of coordinates X, Y, and Z, while the spool filament is
pushed into the printing head at a speed F (mm/min). The
parameter F is often referred to as feed rate. If X, Y, and Z are
not specified, the machine will automatically assign the latest
values; therefore, the machine will not move. If F is not specified, the machine uses the last assigned value. E is the volume of
material being extruded. For Ultimaker 2, this parameter is a
cumulative value; thus for each movement, the value is
increased by the volume of the material extruded during the
current movement. If the printing head of diameter d nozzle
moves from point A(x 1 , y 1 ) to B(x 2 , y 2 ), the value of E is
increased by
ΔE ¼ A nozzle AB ¼ α
À1
nominal AB
¼ π
d nozzle
2
2 ffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffi ffi
x 2 À x 1
ð
Þ
2 þ y 2 À y 1
ð
Þ
2
q
,
ð1Þ
where A nozzle is the area of the nozzle and α nominal ¼ A
À1
nozzle and
AB is the distance between the points A and B (see Note 2).
G1: the machine rapidly moves the printing head to the specified
point. This command is followed by the same options as G1. It
is often used to move the printing head when the machine is
not extruding.
A snippet of G-code is reported in Table 1.
3D Printing of Functionally-Graded Films
33
Equipment
1. Ultimaker 2 printer (Ultimaker).
2. Polylactic acid filament (see Note 1).
2.2 Characterization
Equipment
1. Universal tensile tester equipped with compression plates.
2. Optical microscope equipped with a digital camera.
3 Methods
3.1 G-Code
Instructions
The printer-head movements are controlled by the G-code—a
programming language originally developed to control the tool
path of CNC machines. The commands starting with “G” instruct
the machine as to what the tool path must obey:
G10: the machine retracts the filaments from the printing head and
it stops extruding. This command can be followed by the
option S0 for “short retract” or S1 for “long retract.”
G11: the machine pushes the filament into the printing head and it
starts extruding.
G1: the machine linearly moves to the specified point while extruding the melted material. This command is followed by five
parameters F, X, Y, Z, and E. The printing head moves to the
point of coordinates X, Y, and Z, while the spool filament is
pushed into the printing head at a speed F (mm/min). The
parameter F is often referred to as feed rate. If X, Y, and Z are
not specified, the machine will automatically assign the latest
values; therefore, the machine will not move. If F is not specified, the machine uses the last assigned value. E is the volume of
material being extruded. For Ultimaker 2, this parameter is a
cumulative value; thus for each movement, the value is
increased by the volume of the material extruded during the
current movement. If the printing head of diameter d nozzle
moves from point A(x 1 , y 1 ) to B(x 2 , y 2 ), the value of E is
increased by
ΔE ¼ A nozzle AB ¼ α
À1
nominal AB
¼ π
d nozzle
2
2 ffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffi ffi
x 2 À x 1
ð
Þ
2 þ y 2 À y 1
ð
Þ
2
q
,
ð1Þ
where A nozzle is the area of the nozzle and α nominal ¼ A
À1
nozzle and
AB is the distance between the points A and B (see Note 2).
G1: the machine rapidly moves the printing head to the specified
point. This command is followed by the same options as G1. It
is often used to move the printing head when the machine is
not extruding.
A snippet of G-code is reported in Table 1.
3D Printing of Functionally-Graded Films
33