Qualification of new FDM materials based on weld seam strenght

A component is created in the Fused Deposition Modeling (FDM) process by depositing a polymer strand layer by layer. Due to thermal fusion, the deposited material bonds with the layer below. This leads to the characteristic welded seams of the FDM process. Therefore, an essential part of the qualification of new materials for the FDM process is the evaluation of the processing suitability by means of the weld seam quality. The aim of the research in cooperation with DMRC industrial consortium is to drive forward the material qualification of high-performance polymers.

In the investigations, an innovative methodology developed at the Direct Manufacturing Research Center (DMRC) is used to test the achievable weld seam quality, which enables an assessment of the processing suitability of materials in the FDM process. The tests are carried out on a parameter-open high temperature machine in order to be able to demonstrate the significance of various processing parameters for the processing of high-performance polymers in FDM. Main part of the methodology is the manufacturing of single-strand test specimens with the aim of determining the mechanical strength values of the individual weld seams based on tensile tests.

The investigations demonstrated the suitability of the methodology for high-performance polymers and process parameter optimizations were successfully carried out. In particular, the nozzle temperature and the build chamber temperature have a major influence on the weld seam quality. The following materials were qualified for the FDM process:

• Polyetheretherketone (PEEK), carbon fiber-reinforced PEEK, thermally conductive PEEK
• Polyphenylsulfone (PPSU)
• Polypropylene (PP) with 30 % glass fibers