Abstract
Selective laser sintering (SLS) is a process based on the principle of a locally confined energy input by a laser into a powder bed, producing highly complex parts without the use of moulds or any other tools. In order to ensure good results for the processing behaviour of a new material, the powder must perform well during the phase of feeding the material into the process chamber which majorly influences the quality of the spread of the powder into the part bed and thus the mechanical performance of the final parts. In the present study, the principle of modification of fine powders with flow agents is applied aiming to enable the use of powders for SLS which are otherwise unsuitable due to poor flowability. In addition, the influence of antistatic agent on the powder flow and processing behaviour is discussed. The additives are found to strongly improve the flow behaviour at already very small contents and thus allow for processing of the composite material. The development of determining factors shares insight into the mechanisms of dry particle coating and its implementation into a growing market of material development.
Highlights
An increasing demand for geometrical complexity and the trend to shorter life-cycles of plastic products lead to rising expectations concerning the flexibility and efficiency of production processes
The results indicate that with an increase of the energy input an improvement of the tensile strength and Young’s modulus is achieved
Modifying thermoplastic polymer powders with flow agents via dry particle coating proves to be a potent method for improving the process behaviour in Selective laser sintering (SLS)
Summary
An increasing demand for geometrical complexity and the trend to shorter life-cycles of plastic products lead to rising expectations concerning the flexibility and efficiency of production processes. Many approaches for new materials are based on polymer powders from cryogenic grinding because of the possibility to adjust the composition in a foregoing compounding step These powders are commonly defined by a rough and irregular shape due to the brittle fraction at low temperatures during the grinding process. Along with the dimensional characteristics of the ground powder, poor flowability and a low bulk density are generally observed which results in a bad processing behaviour especially considering the powder coating phase during the generation of a new layer in the SLS process [8, 21] This step is of paramount importance for the resulting part density and the mechanical properties of the final parts [22]. The influence of antistatic agent on the powder flow and processing behaviour will be discussed
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