Mechanical Properties Enhancement of Multi-layer thermoplastics using Kevlar- An Experimental Study

Abstract

Fused Deposition Modeling (FDM) is a type of Additive Manufacturing (AM) in which structures are formed layer-by-layer directly from CAD model, by using thermoplastics. This technique is capable of net shape parts, however, a serious limitation of the process is lower mechanical properties achieved. These properties are even lower than the same thermoplastic parts produced using conventional techniques such as injection molding. Efforts have been made in recent years to improve mechanical properties by reinforcing the parts produced with high strength parts. This has been achieved by either modifying FDM setups to extrude fibers with thermoplastics and fabricate continuous fiber reinforced thermoplastic composites (CFRTPCs) or employing manual techniques subsequent to part production. CFRTPCs fabrication procedures have limitations of fiber exposure to environment, no direct control method for volume fraction and poor surface finish. This research work is focused on improving the process of producing CFRTPCs by addressing these limitations using an off-the-shelf dual extruder FDM setup. The process developed was tested for its feasibility using Kevlar fiber as reinforcement for commercially available ABS, PLA, PLA-C and PLA-Cu thermoplastic fibers. Taguchi L16 Orthogonal Array (OA) was used to design experiments while tensile and flexural testing was performed to determine mechanical properties achieved. Tensile strength was improved up to 3 times the baseline value of thermoplastics while flexural strength was improved up to 1.6 times. Subsequently, parts have been produced to show the feasibility of this process in industrial applications.