Generating Permanent and Temporary Material Compounds in FLM Processes

Abstract

Like all additive manufactured parts, FLM (fused-layer-modeling) components are characterized by a large number of joints between the similar and different materials. These joints can be divided into five categories:- Permanent cohesive bonds between single layers of the same thermoplastic material,- Permanent adhesive bonds between single layers of different thermoplastic materials- Temporary adhesive bonds between single layers of different thermoplastic materials,- Permanent adhesive bonds between a single layer of thermoplastic material and a non-thermoplastic base material,- Temporary adhesive bonds between a single layer of thermoplastic material and a non-thermoplastic base material.The first three types of bonds describe the binding process when parts are manufactured of base material, a second permanently bonded component or a support material that has good release properties. The last two types of connection describe the permanent connection between the printing part and a non-FLM-component or the temporary joint between the printed part and the build platform during the printing process. The resulting compounds can be characterized as material compounds.Since the FLM process is mainly used for design and hobby applications, the fundamentals of the bonding processes and their influence on the internal structure of the material are hardly described. Some information can be taken from the literature for welding plastics and the production of hybrid parts by injection molding. Due to the different pressure and temperature conditions as well as the very large surface-volume-ratio of the discharged strand occur significant differences in the following factors: melt flow, solidification time, formation of surface layers and wetting of the surfaces.The investigation and characterization of these effects as a function of external process parameters is an important constituent for the further development of the FLM process into an industrially suitable manufacturing process for thermoplastic components with very high lightweight and complex geometry in small series etc.