Analysis of the Energy Input During the Sintering Process of Polyamide 12

There is a high growth for additive manufactured parts in the polymer industry. However, especially for laser sintering (LS) also known as powder bed fusion (PBF) the material selection is very limited in comparison to other polymer production processes like, for example, extrusion or injection molding. One major reason for that problem is that there is almost no knowledge which material properties are important for the process and how the material parameters affect the product quality. This is particularly disadvantageous because there are many potential influencing factors for polymer sintering. Thus, a profound understanding of all relevant mechanisms of the PBF process is considered to be lacking. There is almost no link between process parameters, material data and component quality. This causes significant difficulties in developing new materials, as it is for example not known which combination of viscosity and surface tension of the melt lead to the desired product quality in terms of dimensional accuracy. To address this problem, a link between material data, process parameters, and component quality is necessary. This link can be achieved by a combination of experimental investigations, numerical simulations, and analytical considerations to develop dimensionless characteristic numbers (DCN). Our work presents an experimental approach to describe the energy conversion needed during PBF. In this paper the corresponding proposed dimensionless number is compared and validated to mechanical properties of polyamide 12.