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PAPERS: Part Design Methods and Specification Challenges in AM

(Re)Designing for Part Consolidation: Understanding the Challenges of Metal Additive Manufacturing

[+] Author and Article Information
John Schmelzle

NAVAIR Lakehurst,
Lakehurst, NJ 08733
e-mail: john.schmelzle@navy.mil

Eric V. Kline

NAVAIR Lakehurst,
Lakehurst, NJ 08733
e-mail: eric.kline2@navy.mil

Corey J. Dickman

Applied Research Laboratory,
University Park, PA 16802
e-mail: cjd160@arl.psu.edu

Edward W. Reutzel

Applied Research Laboratory,
University Park, PA 16802
e-mail: ewr101@arl.psu.edu

Griffin Jones

Applied Research Laboratory,
University Park, PA 16802
e-mail: gtj109@arl.psu.edu

Timothy W. Simpson

Department of Mechanical & Nuclear Engineering,
The Pennsylvania State University,
University Park, PA 16802
e-mail: tws8@psu.edu

1Corresponding author.

Contributed by the Design for Manufacturing Committee of ASME for publication in the JOURNAL OF MECHANICAL DESIGN. Manuscript received February 27, 2015; final manuscript received June 17, 2015; published online October 12, 2015. Assoc. Editor: David Rosen. This material is declared a work of the U.S. Government and is not subject to copyright protection in the United States. Approved for public release; distribution is unlimited.

J. Mech. Des 137(11), 111404 (Oct 12, 2015) (12 pages) Paper No: MD-15-1172; doi: 10.1115/1.4031156 History: Received February 27, 2015; Revised June 17, 2015

Additive manufacturing (AM) of metallic parts provides engineers with unprecedented design freedom. This enables designers to consolidate assemblies, lightweight designs, create intricate internal geometries for enhanced fluid flow or heat transfer performance, and fabricate complex components that previously could not be manufactured. While these design benefits may come “free” in many cases, it necessitates an understanding of the limitations and capabilities of the specific AM process used for production, the system-level design intent, and the postprocessing and inspection/qualification implications. Unfortunately, design for additive manufacturing (DfAM) guidelines for metal AM processes are nascent given the rapid advancements in metal AM technology recently. In this paper, we present a case study to provide insight into the challenges that engineers face when redesigning a multicomponent assembly into a single component fabricated using laser-based powder bed fusion for metal AM. In this case, part consolidation is used to reduce the weight by 60% and height by 53% of a multipart assembly while improving performance and minimizing leak points. Fabrication, postprocessing, and inspection issues are also discussed along with the implications on design. A generalized design approach for consolidating parts is presented to help designers realize the freedoms that metal AM provides, and numerous areas for investigation to improve DfAM are also highlighted and illustrated throughout the case study.

Copyright © 2015 by ASME
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Figures

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Fig. 1

Main landing gear drag strut retract actuator

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Fig. 2

Schematic for the prototype hydraulic manifold design

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Fig. 3

Original test equipment design using conventional components

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Fig. 4

Final hydraulic manifold with connectors and fittings

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Fig. 5

Stress analysis of various internal passage geometries

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Fig. 6

Results of final stress analysis using diamond-shaped internal passage geometry

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Fig. 7

Generating consistent flow paths in multiple orientations in cad

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Fig. 8

Assembly and interior transitioning from diamond to round cross section passages: (a) assembly drawing with fittings and (b) cutaway view of interior geometry

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Fig. 9

Incorporation of registration features for postprocess machining operations and wrench flats on outer surface

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Fig. 10

Merging complex passages illustrates complex fillet requirements

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Fig. 11

Alignment of features atop mesh influences success of fillets

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Fig. 12

Lightweighting features enabled by AM

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Fig. 13

Example of MBD: (a) documentation for as-built design and (b) documentation for final design postmachining

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Fig. 14

Image of final build layout of the hydraulic manifold and additional test coupons

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Fig. 15

An isometric view and cross section (enlarged) of the reconstructed volume of the manifold obtained from X-ray CT

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Fig. 16

Views of the internal passageways from three orthogonal viewing angles; regions indicated by the arrows show examples of the machining debris that was discovered during the CT scan

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Fig. 17

Impact of build angle on surface roughness: (a) surface roughness versus print angle of as-built part and (b) surface roughness versus print angle of part after shot peen

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Fig. 18

Hydraulic burst test coupon: (a) hydraulic burst coupon tube and (b) analysis showing areas of expected high stress

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Fig. 19

(Re)design approach for part consolidation using metal AM

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Fig. 20

An early design concept that was challenging to fabricate with powder bed fusion: (a) an early design concept for the manifold and (b) support structures required for its build

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Fig. 21

Build layouts in magics (supports shown in red and yellow): (a) optimal orientation to reduce distortion and (b) build orientation for final design

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Fig. 22

Recoater blade contact points with unsupported surfaces which lead to jams

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Fig. 23

Attempt to use fillets to reduce stress risers in internal passageways

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