AMPrint Center

Innovations and Challenges With Multifunctional

Additive Manufacturing

Denis Cormier

Earl W. Brinkman Professor

AMPrint Center Director

AMPrint Center

• Typical Additive Manufacturing– Mechanical/Structural parts

• Housings, gears, etc.

• Light weight metal parts

• Unitized assemblies

• Multifunctional AM– Print devices that can include

mechanical, thermal, chemical, optical, electrical, magnetic…. functionality

– The ultimate in “design freedom”

Multifunctional Printing

Bipropellant Liquid Rocket Engine• Original: 10 piece assembly• Redesign: 1 part with internal

cooling structure for weight reduction and enhanced functional performance

Biggest ROI

AMPrint Center

Multifunctional Printing Examples• Implantable micropump

for drug delivery– Electrical (circuits)– Thermal (resistive

heating)– Mechanical (phase

change pump actuation)

Directional Heat Flow

EnergyAbsorption

Light Pipes

Printed Electronics

Printed Batteries

AMPrint Center

Starting Point – Digital Materials

• Digitally control the material composition at each 3D voxel location– Composition dictates how the material

functions– Color Blending

• Cyan, Yellow, Magenta, Black, White, Clear resins to produce 3D color texturing

– Rigid + Flexible Resin Blends• Vary the Shore hardness value by location

– Electrical + dielectric materials• 3D multi-layer printed electronics

• How do we 3D print with multiple materials?

http://www.architects24.com/news/328-internat-news/1724-ilek-graded-building-components/index.html

Courtesy of Stratasys

AMPrint Center

Multi-Material Printing

• Deposition Methods

– Inkjet Printing

– Aerosol Printing

– Microextrusion

– Others

• Challenges

– Ink/paste formulation

– Thermal processing with dissimilar materials

AMPrint Center

Aerosol Printing• Atomize ink(s) into a fine mist that is

aerodynamically focused through a nozzle– Multi-atomizer configurations allow multi-

material printing

• Innovations– High aspect ratio features (e.g. pillars)

– Magnetically aligned nanowires

– Films with digitally controlled porosity

AMPrint Center

Microextrusion

• Extrude paste through nozzles– Ultra-high solid loading

pastes

• Innovations– Functionally graded

materials• Joining metals with

dissimilar coefficient of thermal expansion

• Graded porosity

– Non-planar 5-axis printing• Compact 3D antennas

AMPrint Center

Inkjet Material Printing• High speed multi-nozzle printing

• Multi-material

• The perfect process, except…– Extremely narrow range of ink viscosity (~10 cP) and

surface tension (~30 dynes/cm)

– Nozzle clogging

– High capital expense and maintenance costs

Surface tension/wetting issues

Drop watcher

Satellite drops and/or perpendicularity issues

AMPrint Center

• Pulsed Photonic Curing/Sintering– Rapid curing/sintering of high

temperature printed materials (e.g. metal or ceramic) on low temperature surfaces (e.g. paper or plastic).

– Novacentrix pulsed photonic curing/sintering• High power Xenon strobe lamps

• Peak Power: 100 kW/cm2

• Sustained Power: 5 MW/pulse

• Pulse Length: Down to 25 μsec

• Pulse Rate: Up to 1 kHz

Thermal Processing of High Temperature Materials on

Thermally Sensitive Substrates

Before:

After:

Novacentrix Pulseforge 3300

AMPrint Center

Practical Challenges With Functional Inks

• Nanoparticle ink stability and shelf life

• Effect of additives on functional performance

• Adhesion of printed nanoparticle inks to surfaces

• Drying defects (cracking + coffee ring)

• Uniformity of printed film thickness with different inks

• Rheology limits for each printing process

AMPrint Center

Summary

• Multifunctional printing has tremendous potential to further increase the “design freedom” of AM/3DP.

• Formulation of inks/pastes and optimization of processes requires great care

– Print process compatibility

– Compatibility between materials

– Coverage of large areas vs. printing of fine features

– Equal deposition thicknesses