Effects of walnut shell powder content on the molding performance of digital light processing 3D printed parts

Additive Manufacturing (AM) is a digital manufacturing method that creates structures by adding material layer by layer. This approach offers simplicity, speed, and efficiency. Additive manufacturing methods can process wood-plastic composites, but they are often limited by poor surface quality, low interfacial bonding, and the requirement for complex post-processing. In this study, walnut shell and photosensitive resin were used to fabricate wood-plastic composite specimens with varying walnut shell powder contents using DLP technology. The properties analyzed included dimensional shrinkage, mechanical strength, double bond conversion rate, and microstructure. The results indicated that as the walnut shell content increased, the dimensional shrinkage of the formed parts initially decreased and then increased, reaching the minimum value of 0.631% at 12% walnut shell powder content. SEM imaging revealed that resin infiltrates the particle pores, forming a network structure that enhances mechanical performance. Tensile and flexural strengths also reached their peak values at 8% content, measuring 17.7 and 45.4 MPa, respectively, while impact strength decreased with increasing walnut shell content.