Modeling of powder particle heat transfer process in selective laser sintering for fabricating tissue engineering scaffolds

Abstract

PurposeTissue engineering (TE) involves biological, medical and engineering expertise and a current engineering challenge is to provide good TE scaffolds. These highly porous 3D scaffolds primarily serve as temporal holding devices for cells that facilitate structural and functional tissue unit formation of the newly transplanted cells. One method used successfully to produce scaffolds is that of rapid prototyping. Selective laser sintering (SLS) is one such versatile method that is able to process many types of polymeric materials and good stability of its products. The purpose of this paper is to present modeling of the heat transfer process, to understand the sintering phenomena that are experienced by powder particles in the SLS powder bed during the sintering process. With the understanding of sintering process obtained through the theoretical modeling, experimental process of biomaterials in SLS could be directed towards the appropriate sintering window, so as not to cause unintentional degradation to the biomaterials.Design/methodology/approachSLS uses a laser as a heat source to sinter parts. A theoretical study based on heat transfer phenomena during SLS process was carried out. The study identified the significant biomaterial and laser beam properties that were critical to the sintering result. The material properties were thermal conductivity, thermal diffusivity, surface reflectivity and absorption coefficient.FindingsThe influential laser beam properties were laser power and scan speed, which were machine parameters that can be controlled by users. The identification of the important parameters has ensured that favorable sintering conditions can be achieved.Research limitations/implicationsThe selection of biopolymer influences the manner in which energy is absorbed by the powder bed during the SLS process. In this paper, the modeling and investigative work was validated by poly(vinyl alcohol) which is a biomaterial that has been used for many biomedical and pharmaceutical purposes.Practical implicationsThe paper can be the foundation for extension to other types of biomaterials including biopolymers, bioceramics and biocomposites.Originality/valueThe formulation of the theory for heat transfer phenomena during the SLS process is of significant value to any studies in using SLS for biomedical applications.