PSI - Issue 37

Tiago Domingues et al. / Procedia Structural Integrity 37 (2022) 847–856 Author name / Structural Integrity Procedia 00 (2019) 000 – 000

849

3

have higher working temperatures and better mechanical properties when compared to commonly used filament materials. In terms of temperatures, it can be seen that PEEK and PEI have higher glass transition temperatures than PLA, PETG or ABS, and consequently higher working temperatures as well as higher printing temperatures. It can also be deduced from Table 1 that these high-performance plastics have better mechanical properties because they have a higher young modulus and yield strength when compared to the common use plastics.

Table 1 -FFF printable plastics reference thermal and mechanical properties

Hot-end Temperature (°C)

Glass-Transition Temperature (°C)

Density (g/cm 3 )

Young Modulus (MPA)

Yield Strength (MPA)

Designation

PLA (3DXTECH, n.d.) PTEG (3DXTECH, n.d.) ABS (3DXTECH, n.d.) PEEK (3DXTECH, n.d.) PEI (3D4MAKERS, n.d.)

190-220 230-260 220-240 375-410 355-390

55 80

1.24 1.24 1.05

2865 1650 1950 3720 3200

56 45 42

105 143 217

1.3

100 105

1.27

2. Methods The challenge proposed in this article was to produce a machine capable of manufacturing high-performance plastic components by the FFF method. To clarify the objective, the PEEK and PEI ULTEM 1010 materials from the supplier 3D4Makers were chosen to be printed in the developed equipment. The printing temperature requirements for these two materials are shown in Table 2. From the analysis, it was possible to define the requirements for the machine setting a 20 ºC margin above the maximum material requirements for each parameter. Through this process, it was concluded that a hotend capable of reaching a temperature of 420 ºC, a bed surface capable of reaching 140 ºC, and a heated environment capable of reaching 120 ºC were needed. In addition to these, there was only the need for the other kinematic and structural components to withstand these temperature demands. The basic strategy defined to execute this project was to use an existing 3D printer and modify it to meet the defined requirements. The 3D printer selected was the 3D Systems CubeX, which has the factory specifications of having an extruder capable of reaching 280 ºC, a print bed with no heating and no closed enclosure for a heated environment. By comparing the specifications of the existing printer with the defined requirements, it was concluded that the maximum temperature of the nozzle should be increased to 420 ºC, by changing the extruder, a heated bed capable of reaching 170 ºC had to be added and a closed chamber that would allow an environment with a controlled temperature reaching up to 120 ºC had to be implemented. In addition, two other modifications were deemed necessary. The first is the necessity of a cooling system for the steeper motors that run the machine, as the 120 ºC environment impairs the proper functioning of these components. Second, there was the needed to change the control unit of the machine in order to allow the implementation of open-source software which would give greater configuration flexibility to allow for the implementation of all the necessary changes.

Table 2 – 3D4MAKERS PEEK and PEI printing parameters

High-Performance Plastic PEEK (3D4MAKERS, n.d.) PEI (3D4MAKERS, n.d.)

Nozzle Temperature (°C)

Bed Temperature (°C)

Ambient Temperature (°C)

360-400 340-360

120 120

100

Not mentioned

To tackle the implementation of the three necessary changes, two types of strategies were implemented, firstly, the acquisition of existing components in the market for the extruder and the heated bed, and then the development of a customized solution for the heating environment. For the extruder component it was decided to acquire the commercial solution Titan Aqua by the company E3D, shown in Figure 1 (a), since this solution presented the capability of reaching temperatures up to 500 ºC and had the particularity of being water cooled which was important since an air-cooling system would be very inefficient in a heated environment. The only change to the