The effects of printing speed and infill density on mechanical properties by using Fused Deposition Method (FDM) for medical implant

Medical implant is commonly used in order to generate damaged tissue in patient’s body. Bone tissue engineering is one of the methods to generate new structure of bone tissue. However, development of bone tissue engineering must consider the material of the component in terms of the properties and the biocompatibility. In addition, conventional fabrication technique was used previously but the problems found in customization of the parts and less cost effective. Therefore, Polylactic Acid (PLA) was introduced for used in medical implant as it gave compatible mechanical properties for human body and Fused Deposition Modeling (FDM) as additives manufacturing process used to fabricate the samples. Thus, this study focused on determining the effects of different printing parameters on its mechanical properties on PLA material by using 3D printing method. 27 samples of Dog-bone shape based on ASTM D638 standard were fabricated using FDM with PLA material. Two printing parameters which were printing speed (80mm/s, 100mm/s and 120mm/s) and infill density (30%, 60% and 90%) were set and had been tested on tensile testing machine to determine the mechanical properties of the samples. Based on previous studies, the suitable ultimate tensile strength for human bone was around 51MPa to 133MPa with Young’s Modulus around 1GPa to 22.3GPa were set as a reference value. The highest value of tensile strength and Young’s Modulus gained from the parameter 100 mm/s printing (22.3147 MPa) and 90% infill density (0.8419 GPa) respectively. Finite Element Analysis was conducted on lattice scaffold design using mechanical properties of optimum printing parameters which was 100 mm/s speed with 90% infill. Result showed that maximum stress (Von Misses) was 20.6408 MPa and minimum stress was 0.688 MPa. The lattice scaffold design then was fabricated using optimum printing parameters as a prototype. These findings as a prior study will be beneficial for future research in medical field.