TY - CONF

T1 - The consequences of different printing chamber temperatures in extrusion-based additive manufacturing

AU - Spörk, Martin

AU - Arbeiter, Florian

AU - Raguz, Ivan

AU - Traxler, Gerhard

AU - Schuschnigg, Stephan

AU - Cardon, Ludwig

AU - Holzer, Clemens

PY - 2018/9/21

Y1 - 2018/9/21

N2 - Materials that are processed by means of extrusion-based additive manufacturing are exposed to complex temperature conditions during manufacturing, resulting from quick temperature alterations due to the moving nozzle. Consequently, a rather inhomogeneous temperature distribution is present in the printing chamber, which can intensify issues such as high internal stresses, unintentional crystal growth and undesired part deformations. This study aims at tackling these problems by investigating the consequences of increased printing chamber temperatures on 3D-printed polypropylene (PP). In-situ thermography measurements during printing revealed a drastic decrease in the temperature fluctuations as soon as parts are printed at a controlled increased chamber temperature, leading to a more homogeneous temperature distribution. As a result, internal stresses declined and the warpage of printed parts considerably decreased compared to the conventionally used surrounding room temperature. Since the maxima of the strand temperatures easily surpass 100 °C for a chamber temperature of 55 °C, the crystal modification partly changed from α-PP to β-PP, which was con-firmed by thermograms and X-ray diffraction. As the mean strand temperatures during printing are in the close proximity of the temperature of the maximum crystal growth rate of PP, fewer and bigger, but more homogeneous spherulites were formed. Additionally, shish-kebab structures tended to form at high chamber temperatures due to strong process orientations. The found crystallographic changes introduced by changes in the printing chamber temperature can be employed to tailor the material properties of 3D-printed PP. The proposed strategy can act as the foundation for similar studies on other printable semi-crystalline polymers.

AB - Materials that are processed by means of extrusion-based additive manufacturing are exposed to complex temperature conditions during manufacturing, resulting from quick temperature alterations due to the moving nozzle. Consequently, a rather inhomogeneous temperature distribution is present in the printing chamber, which can intensify issues such as high internal stresses, unintentional crystal growth and undesired part deformations. This study aims at tackling these problems by investigating the consequences of increased printing chamber temperatures on 3D-printed polypropylene (PP). In-situ thermography measurements during printing revealed a drastic decrease in the temperature fluctuations as soon as parts are printed at a controlled increased chamber temperature, leading to a more homogeneous temperature distribution. As a result, internal stresses declined and the warpage of printed parts considerably decreased compared to the conventionally used surrounding room temperature. Since the maxima of the strand temperatures easily surpass 100 °C for a chamber temperature of 55 °C, the crystal modification partly changed from α-PP to β-PP, which was con-firmed by thermograms and X-ray diffraction. As the mean strand temperatures during printing are in the close proximity of the temperature of the maximum crystal growth rate of PP, fewer and bigger, but more homogeneous spherulites were formed. Additionally, shish-kebab structures tended to form at high chamber temperatures due to strong process orientations. The found crystallographic changes introduced by changes in the printing chamber temperature can be employed to tailor the material properties of 3D-printed PP. The proposed strategy can act as the foundation for similar studies on other printable semi-crystalline polymers.

M3 - Paper

T2 - International Conference on Polymers and Moulds Innovations - PMI2018

Y2 - 19 September 2018 through 21 September 2018

ER -