Process-Dependent Influences on Adhesion in Multi-Material Extrusion

The complexity offered by additive material extrusion (MEX) presents new opportunities for novel design, especially with regard to multi-material components. However, this design freedom has heretofore only been scarcely used thus stifling innovation. One reason for this development is the complicated nature of adhesion at the interface of multi-material parts. Hence, this publication aims to investigate the process-dependent influences in multi-material MEX by conducting tensile tests on ABS-PLA multi-material specimens. By implementing a distance gauge into the tool change procedure, positional fluctuations of the nozzle will be eliminated and the effects of extrusion temperature, line placement, and over- or under-extrusion on composite strength can be determined more precisely. In addition, thermal imaging is conducted to give an informed estimate of the effects of build chamber or build plate temperature on diffusion at the material interface. The results show a clear influence of extrusion temperature and over-extrusion on composite strength, while the effect of line placement is determined to only be minor. The build chamber temperature is predicted to have no meaningful effect on composite strength. Overall, the results suggest that deviations in printer calibration, by as little as 0.04 mm, can have a significant influence on composite strength.