This study focuses on the filament extrusion process of high-density polyethylene (HDPE) to be used in fused filament fabrication (FFF). Extruding the filament from pure HDPE and 3D printing with it poses significant challenges, therefore commercial products such as Taulman’s T- LyneTM, which is a unique material employing Polyolefin (PP & PE) compatibilizers like Surlyn®, are available. In this study, we explore using wax in place of the compatibilizers used by the industry. To investigate the applicability of this approach and optimize the process, a study based on the design of experiment (DOE) methodology is adapted, and factors such as the wax content by volume and number of grinding passes are chosen as the input factors to be analyzed from filament quality point of view. For this purpose, extrusion runs based on three different wax content by weight (i.e., 5%, 10%, and 15%), and five different number of grinding passes (1,2,3,4, and 5) are conducted. The number of grinding passes indicates how many ground by laboratory mill-extrude cycle is conducted for obtaining the filament. It should be noted that it was not possible to extrude a filament with consistent thickness with 15% wax content and/or single grinding pass. For all other combinations of the wax content and number of grinding passes, extrusion runs are conducted and data indicating the diameter of the extruded filament are collected using a digital caliper. Performance measures based on the accuracy and precision of the diameter of the filament for determining the quality and suitability for the 3D printing process are developed, and a statistical analysis is conducted on the comparison of levels of chosen input factors using the t-tests.
Learning Objectives:
- Upon completion, participant will be able to assess the applicability of the novel approach for improving extrudability of HDPE filament using wax additive.
- Upon completion, participant will be able to develop an understanding of design of experiment based approach to improve the quality characteristics of the HDPE filament.
- Upon completion, participant will be able to define key performance measures based on accuracy and precision for assessing the quality of HDPE filament for the 3D printing applications.
