Characterisation of the thermal ageing effects on the mechanical properties when reusing polyamide 12 in the selective laser sintering process

Abstract

Additive manufacturing is one of the key technologies for the future production of complex and individualised components. One of the most challenging questions to minimize the production cost is the reuse of the powder leftover after the building process. This study investigates the influence on the mechanical properties when reusing the leftover powder out of the process chamber up to four times. Tensile test specimens are produced and investigated. The results show a decreasing in the ultimate tensile strength with repeated reuse of the leftover powder. After four times of reuse the strength increases again. This cannot be explained by the literature and has to be verified in further investigations. The investigations reveal a high mechanical anisotropy as the strength highly depends on the component orientation in the process chamber. The particle shape does not show any differences between virgin and aged powder under the scanning electron microscope.

Influence of Atmospheric Conditions on Mechanical Properties of Polyamide with Different Content of Recycled Material in Selective Laser Sintering

“…Influence on mechanical properties when reusing the powder leftover from the process chamber up to four times was investigated in the study of authors du Maire, P. et al [24]. Tensile test specimens were produced and tested.…”

An experimental and theoretical investigation on the hyper- viscoelasticity of polyamide 12 produced by selective laser sintering

“…Accordingly, the results are practically assumed the same in this study, and the SLS-produced specimens are considered isotropic. It has been proved [30,31] that possible anisotropy is significantly suppressed if, as is fulfilled in current work, recycled powders are not used in selective laser sintering. The force-displacement response shown in Fig.…”

Characterisation of the mechanical properties of polyamide 12 powder when using titanium dioxide as antimicrobial additive

“…The printer operates with a 100 W carbon dioxide laser and has a possible build volume of 380 mm×330 mm×275 mm. As already investigated in previous studies, the orientation of the samples in the building chamber has a significant influence on the mechanical properties, i. e., the tensile strength, but since this is not the subject of this work, the specimens are only manufactured in one orientation [11, 17, 18]. They are placed parallel to the scanning direction of the printer, i. e., the testing direction corresponds to the scanning direction.…”

“…Combining these material properties with an additive manufacturing process can open up new potential and expand the product range. In polymer production, selective laser sintering is the most significant additive manufacturing process and is, due to the high accuracy of the sintered parts, currently at the transition stage from prototype manufacturing to series production [3, 7–11]. The selective laser sintering process is a powder based additive manufacturing technology, where the powder is successively applied in thin layers to the construction area and then melted locally using a carbon dioxide laser.…”