Predicting the neck size in the fused filament fabrication process

This study focuses on neck growth in the fused filament fabrication process and aims to propose an experimentally validated model for predicting the neck size. For this purpose, two different neck growth models are developed based on the sintering mechanism and intimate contact mechanism. For experimental measurements, ABS material is used throughout the study to fabricate forty-five different test specimens. Since the sintering mechanism, which the literature addresses as the primary mechanism for studying the neck size, highly depends on filament temperature, a 3D heat transfer model is also developed and validated with experimental data. Comparing the predicted results with experimental measurements clearly indicate that the sintering mechanism makes a small contribution to the total neck growth and can be safely ignored. On the contrary, the model developed based on the contact pressure idea, which has mostly been neglected in the literature, proved to have promising results in predicting the neck size. The main advantage of our developed model ( W_bond≈ W.(C_1WV_noz/H^2)^1/5 ) is that it can predict the neck size based on the printing parameters with no need for any experimental measurements.