Curling (a) and coating defects (b) in SLS processes with plastic powder

© M. Bublin

Curling (a) and coating defects (b) in SLS processes with plastic powder

The figure shows curling (a) and coating defects (b) in SLS processes with plastic powder.

Supervisor: M. Bublin

Co supervisor: A. Otto

PhD student: V. Klamert

Objectives: There are already many in situ measurement methods, which monitor the process of selective laser sintering (SLS) with polymer powders. However, process monitoring is an important topic for determining the print quality and the mechanical properties of the components and should be improved during the PhD project. The efficiency of SLS processes for polymers increased by non-destructive analysis, since the reject is reduced by using predictive models. In addition, the aim is to replace sample examinations of the components with process monitoring and subsequent modelling of the influences in the event of errors in the process.

Defects in the powder bed, such as coating defects, uneven distribution of the powder over the installation space and uneven temperature distribution over the sintering process have a negative impact on the material properties of the component. This can lead to the fact that the manufactured components cannot be used for their intended purpose. In order to be able to assess the quality of the components after production, in situ measurement methods should be developed and implemented in the SLS system.

Shift errors can be detected using these measuring methods. With sufficient measuring accuracy of the methods, their influences on the subsequent layers of the components should also be determined. For this purpose, powder defects are specifically created, and their influence is determined.

In addition, dummy samples are produced to measure the effects of the errors on the material properties. Standard measuring methods are used to characterize the material properties (determination of tensile strength, bending strength, surface topology ...).

Based on the measurement data and the measurements of the material properties, a model should be created that describes the quality of the component in the SLS process. For this purpose, close coordination with the TUW, which contributes the material simulations, is required.

It is planned that the PhD candidate will continuously define and supervise theses (master and bachelor theses) from the aforementioned subject area during the doctorate.