A. Sebert, J. Nelson, G. Bertacco
Keywords: 3D printing, injection molding, polymer, mechanical performance, tensile testing, impact testing
Summary:As 3D printing continues to grow as a viable manufacturing process, quantification of the processing options and parameters will allow for better design and modeling of printed parts, or at least clearly understand the trade-offs between the different options. To address this, a long-term, collaborative effort has been undertaken by the authors to accurately predict the properties of 3D-printed parts. 3D Matter has developed a model, Optimatter (www.optimatter.com), to fulfill this need by realizing an expanded the range of applications where 3D printing can be a viable manufacturing process. In order for accurate property prediction, understanding the processing-performance relationship is needed. The work presented specifically quantifies the differences between injection molding and 3D printing while also quantifying the differences between professional and personal 3D printing. A survey of the literature in this area indicated that certain aspects have been tested, direct comparison of the same material processed in these three ways has not been performed. As such, a study was carried out processing two materials (nylon and ABS) using injection molding, a professional grade FDM printer, and a personal grade FDM printer to make standard coupons for both tensile and impact testing. Standard test methodologies were followed and print orientations were adjusted for comparison of print orientation on properties. The result was four main findings: the 3D printing process leads to lower mechanical performance than injection molding; within 3D printing, there is a decrease in performance along the Z-axis for both personal and professional printing; the properties along the X/Y-axes are very similar between the professional and the personal printers; and, the properties along the Z-axis are significantly better on the professional printer than on the personal printer. In addition, comparisons of time, cost, and quality of each process have been considered indicating that each process is able to meet certain needs. Overall, the differences between injection molding and 3D printing have been clarified as well as the variations between printer grades while using material from the same lot for each process.