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Marquette University | Milwaukee School of Engineering | Purdue University | University of California, Merced | University of Illinois, Urbana-Champaign | University of Minnesota |
Vanderbilt University
Metal Big Area Additive Manufacturing for
Fluid Power Applications
Clayton Greer, GT-ORNL RAMP-UP Fellow
Georgia Institute of Technology
Advisor: Dr. Thomas Kurfess
Industry/University Engagement Summit
June 6 – 8, 2016
photo
2
Metal BAAM for Structural Applications in
Fluid Power
Deliverables: 3D
Printed Excavator
Boom
Next Steps
• Research goals: We aim to produce metal
structural components that are measured in
feet, not inches, using additive
manufacturing.
• Developing design rules and techniques for
large scale additive manufacturing with
ORNL’s Manufacturing Demonstration
Facility.
• Competing research: large scale additive
manufacturing has been done before:
• Laser
• Electron beam
• Nickel-based superalloys, Ti alloys
• Original contribution: we will develop arc
weld deposition using standard steel
welding filler wire.
• 6 months:
• Printing large scale components
• 1 year:
• Printing excavator components
live at the largest construction
show in North America
• Demonstrate taking advantage of additive
manufacturing in fluid power
• Excavator featuring internal
hydraulics
• Develop manufacturing system (mBAAM)
for printing large metal structures
3
Additive Manufacturing Overview
FDM - MakerbotBAAM - ORNL
SLM – Concept LasermBAAM - ORNL
4
Additive Manufacturing Overview
Process Material Build VolumeMaterial
CostSpeed Resolution
FDM ABS
0.2 cubic ft
(6in x 6in x
6in)
ABS
Filament
$80/lb
0.05 lbs/hr Yoda head
BAAMABS/Carbo
n Fiber280 cubic ft
CF-ABS
Pellets
$5/lb
100 lbs/hr Car
Metal
Powder
Bed
Ti, Ni,
Stainless,
Aluminum
0.3 cubic ft
(8in x 8in x
8in)
Atomized
Ti-6Al-4V
Powder
$600/lb
0.3 lbs/hrAerospace
brackets
mBAAMSteel,
Aluminum30 cubic ft
Steel Filler
Wire
$6/lb
10 lbs/hrMini-
excavator?
5
GTAW/TIG in 3D Printing
7 DoF robotic arm
TIG welder
Cold wire
feeder
Camera for torch
observation
6
Biggest issue – residual stress
• Arc welding produces higher
thermal gradients than laser or E-
beam
• 3D thermomechanical simulation
for residual stress and distortion
predictions.
• Using SAMP as a pre-processor
for Abaqus.– Material properties
– Energy source
– Path scheduling
7
Ambient temperature envelope
y = 0.2432x + 540.25
0
100
200
300
400
500
600
700
800
900
1000
0 100 200 300 400 500 600
Tem
pera
ture
(K
)
Time (sec)
Temperature distribution of Node #1626
Node 1626
• Welder current as a function of layer
8
Design Rules for mBAAM
• Thermal management
– Inter-pass temperatures need to be regulated
– Thermal model will predict the amount of cool-off time needed
• Print direction
– Internal hydraulics: circular lines vs diamond lines
– Overhangs
• Open question: what is the minimum feature size for
mBAAM?
– Design specs for excavator < 15 mm diameter lines
9
“Optimized” Excavator Design
• Topology optimization in
Abaqus
– Only considers prescribed
loading and geometry
• Design for 20% weight
reduction
• Integrated hydraulic lines
– No hoses or tubing
– Will need a solution to prevent
working fluid contamination
Generalized boom loading
~10 feet
10
Internal hydraulic lines
Pressurized lines
3.1mm deflection
No pressure
“Demold control” on
14.5mm deflection
• Internal hydraulic lines on top and bottom
• Evidence for pressurized lines reducing vertical deflection
• Higher stresses, but more material where it is needed
• Need to produce a stiffer boom
11
Upcoming schedule
Summer 2016
• Print 3 foot long structure with steel
• Evaluate material properties
• Generate complex structures
Fall 2016
• Print prototype boom
• Upgrade to Wolf Robotics system
Winter 2016
• Print, post-process, and assemble additively manufactured
excavator
• Gear up for CONEXPO 2017
12
Summary
• What have we done?
– Excavator topology optimization
– ORNL has begun printing with a prototype mBAAM,
we are still early in the process.
– The Wolf system will arrive this summer.
• What have we NOT done?
– Complex geometries
– CAD-to-part testing
– Intelligent path planning
– Excavator design validation
13
How can industry help?
• Design feedback
– Stiffness
– Durability
– Weight reduction numbers
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