Withdrawal Capacity of Double-Threaded Nuts Mounted in 3D-Printed Wood-Plastic Composites

This paper investigated the withdrawal capacity of the double-threaded nuts mounted in 3Dprinted materials. The basic technical properties and the withdrawal force of the double-threaded nuts for the specimens made of PLA, WPLA, and layered WPLA+PLA configuration (with and without STP adhesive) were investigated. The results are compared with the literature data of withdrawal force for beech wood, MDF, and particleboard with and without the adhesive. The research has determined the effects of the properties of 3D printed materials (density, compressive and tensile strength), the infill and printing patterns, and adhesive on withdrawal capacity of double-threaded nuts. Double-threaded nuts mounted with adhesive had higher withdrawal forces (about 25 % for PLA and WPLA specimens, and 15 % for layered WPLA+PLA specimens) than those mounted without adhesive. The highest values of withdrawal forces, regardless of the adhesive, were obtained for layered WPLA+PLA configuration, followed by WPLA, and the lowest for PLA. No significant difference was found between the withdrawal forces for WPLA and layered WPLA+PLA specimens for both cases – with and without an adhesive. The withdrawal forces of double-threaded nuts for the PLA specimens were higher than the withdrawal forces for the beech (16.7 % mounted without adhesive and 11.6 % mounted with an adhesive), and other combinations showed a difference higher than 35 % in favor of 3D printed materials. The present analysis, which determines and compares used traditional dismountable connectors in 3D-printed furniture elements, is applicable for research and practice.