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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

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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

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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

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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

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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

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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

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How can industry help?

• Design feedback

– Stiffness

– Durability

– Weight reduction numbers