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oai:dspace.mit.edu:1721.1/1399572022-02-08T03:11:23Zcom_1721.1_7582com_1721.1_7581col_1721.1_131022

Hart, A. John Stevens, Adam Gregory Massachusetts Institute of Technology. Department of Mechanical Engineering 2022-02-07T15:15:40Z 2022-02-07T15:15:40Z 2021-09 2021-09-30T17:29:25.564Z https://hdl.handle.net/1721.1/139957 Fused filament fabrication (FFF) is an additive manufacturing (AM) process in which a polymer feedstock is melted and extruded through a nozzle while guided by a motion system, resulting in a three-dimensional part. FFF is applicable across a range of length scales and with a wide variety of thermoplastic polymers and composites. As such, FFF is increasingly used in prototyping, low volume production, and tooling/fixture applications. One of the drawbacks to FFF is its low build rate, which is limited by the fundamentally serial nature of the process–a single printhead must traverse a trajectory that spans the entire built volume of the part while depositing material. As a result, the build rate is governed by the performance of the motion and extrusion systems. This thesis explores the influence of motion and extrusion system design on FFF build rate by: 1) deriving a set of design rules for FFF systems that maximize rate, subject to specified quality constraints and guided by finite element analyses and parametric models; 2) the mechanical design and construction of a servo-driven FFF testbed that uses a parallel H-frame belt drive; and 3) implementing closed-loop servo control with the aforementioned hardware and assessing axis-level motion performance and overall print quality using test artifacts. Performance of the custom-built FFF system is benchmarked against the models in (1), and against commercial FFF systems, and rate-resolution tradeoffs are quantified. This thesis concludes with suggestions for further machine design and process control improvements for FFF AM. Ph.D. Massachusetts Institute of Technology In Copyright - Educational Use Permitted Copyright MIT http://rightsstatements.org/page/InC-EDU/1.0/ High throughput extrusion additive manufacturing – rate limits and system design Thesis application/pdf Doctoral Doctor of Philosophy Publication unknown unknown <Publication xmlns="https://www.openaire.eu/cerif-profile/1.1/" id="cdb41c2a-d5b8-488c-ab94-3298d83fd44d"> <Type xmlns="https://www.openaire.eu/cerif-profile/vocab/COAR_Publication_Types">http://purl.org/coar/resource_type/c_1843</Type> <Title>High throughput extrusion additive manufacturing – rate limits and system design</Title> <PublishedIn> <Publication> </Publication> </PublishedIn> <PublicationDate>2021-09</PublicationDate> <Authors> <Author> <DisplayName>Stevens, Adam Gregory</DisplayName> <Affiliation> <OrgUnit> </OrgUnit> </Affiliation> </Author> </Authors> <Editors> </Editors> <Publishers> <Publisher> <DisplayName>Massachusetts Institute of Technology</DisplayName> <OrgUnit /> </Publisher> </Publishers> <License>http://rightsstatements.org/page/InC-EDU/1.0/</License> <Abstract>Fused filament fabrication (FFF) is an additive manufacturing (AM) process in which a polymer feedstock is melted and extruded through a nozzle while guided by a motion system, resulting in a three-dimensional part. FFF is applicable across a range of length scales and with a wide variety of thermoplastic polymers and composites. As such, FFF is increasingly used in prototyping, low volume production, and tooling/fixture applications. One of the drawbacks to FFF is its low build rate, which is limited by the fundamentally serial nature of the process–a single printhead must traverse a trajectory that spans the entire built volume of the part while depositing material. As a result, the build rate is governed by the performance of the motion and extrusion systems. This thesis explores the influence of motion and extrusion system design on FFF build rate by: 1) deriving a set of design rules for FFF systems that maximize rate, subject to specified quality constraints and guided by finite element analyses and parametric models; 2) the mechanical design and construction of a servo-driven FFF testbed that uses a parallel H-frame belt drive; and 3) implementing closed-loop servo control with the aforementioned hardware and assessing axis-level motion performance and overall print quality using test artifacts. Performance of the custom-built FFF system is benchmarked against the models in (1), and against commercial FFF systems, and rate-resolution tradeoffs are quantified. This thesis concludes with suggestions for further machine design and process control improvements for FFF AM.</Abstract> <Access xmlns="http://purl.org/coar/access_right" > </Access> </Publication>