Abstract
A fused filament fabrication (FFF) 3D printer is a simple device capable of manufacturing three-dimensional structures in a series of easy steps. Commercial-level FFF 3D printers have spread rapidly in many fields in recent years. Poly(lactic acid) (PLA) is a biodegradable thermoplastic polymer used as a typical printing medium for FFF 3D printers. The FFF printer constructs an object with melted polymer extruded from a tiny scanning nozzle. The mechanical properties of FFF 3D structures printed with different scan patterns can therefore vary in accordance with the directions from which forces act upon them. The nozzle scan pattern also influences the deterioration of the mechanical properties of the structures in accordance with the degradation caused by the hydrolysis of PLA. In this study we conducted tensile tests to evaluate the strength characteristics of 3D printed test pieces formed from PLA using four different scan patterns: parallel, vertical, parallel-and-vertical, and cross-hatched at opposing diagonal angles to the tensile direction. We also formed test pieces by an injection molding method using the same material, for further comparison. We evaluated the deterioration of the test pieces after immersing them in saline for certain periods. After the test pieces formed by different nozzle scan patterns were immersed, they exhibited differences in the rates by which their maximum tensile stresses deteriorated and their masses increased through water uptake. The influences of the scan patterns could be classified into two types: the unidirectional scan pattern influence and bidirectional scan pattern influence. The data obtained in this research will be applied to structural design when the FFF 3D printer is employed for the fabrication of structures with PLA filament.
Highlights
Fused deposition modeling (FDM) is a fabrication method used for the rapid prototyping (RP)of objects by the process broadly known as additive manufacturing (AM)
While thethe forms of theThe testphotographs pieces looked same,the theexternal different nozzle scanofpatterns to fabricate test of the test pieces looked almost the same, the different nozzle scan patterns used to fabricate the test pieces resulted in visible differences in the surface states
Poly(lactic acid) (PLA) test pieces fabricated by fused filament fabrication (FFF) 3D printing and by I.M. were immersed in saline and examined by tensile tests to determine their respective strength characteristics
Summary
Fused deposition modeling (FDM) is a fabrication method used for the rapid prototyping (RP). Of objects by the process broadly known as additive manufacturing (AM). An FDM 3D printer builds objects by depositing melted thermoplastic material extruded from a tiny scanning nozzle. A computer moves either the nozzle or stage layer-by-layer based on instructions coded in a standard triangulated language (STL) format exported from a three-dimensional computer-aided design. The FDM was originally developed by Scott Cramp in 1988 [4,5] and later commercialized by Stratasys Inc. in 1990 [4]. Though the original apparatus had excellent stability and precision for fabrication, it was too large and expensive to be readily adopted on a commercial basis. When the Stratasys patent on FDM technology expired, the name “FDM 3D printer” came to be Inventions 2019, 4, 21; doi:10.3390/inventions4010021 www.mdpi.com/journal/inventions
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