Functionally Graded Materials (FGMs) are characterized by a continuous variation in the composition of parent materials through the work piece volume. This gradual change in material composition is aimed at improving mechanical, thermal and/or electrical properties of the material. FGMs are being increasingly used in a variety of applications including aerospace, biomedical and nuclear.

FGMs have been produced using additive manufacturing processes such as laser engineered net shaping (LENS) and 30 printing. A relatively new process category called direct write (OW) printing has evolved over the past decade. OW techniques such as multi-material micro-extrusion are capable of producing FGMs. To fully utilize the capabilities of multi-material micro-extrusion, experimentation and modeling is needed to determine the factors that significantly affect the mass flow rate and proportion of each nanoink being dispensed. The objectives of this study were to develop a parametric model for multi-material pneumatic microextrusion and to develop equations to determine the parameter values to achieve the desired ink proportions during ink deposition.

Experiments were conducted using red, blue and yellow acrylic inks that were printed using a commercially available three material pneumatic micro-extruder from nScrypt.

Preliminary experiments determined that air pressure and valve needle position were significant parameters affecting the mass flow rate of the inks. A 26 experiment was then designed and carried out. Parametric equations thus developed provided relationships between the parameter values and the proportions of inks dispensed. The equations were validated by solving them using an AMPL linear program. For a given desired proportion of inks to be dispensed, the AMPL program suggests process parameter values needed to produce the desired multi-material output.

Library of Congress Subject Headings

Functionally gradient materials--Design and construction--Mathematical models; Nanostructured materials

Publication Date


Document Type


Student Type


Degree Name

Industrial and Systems Engineering (MS)

Department, Program, or Center

Industrial and Systems Engineering (KGCOE)


Denis Cormier

Advisor/Committee Member

Marcos Esterman

Advisor/Committee Member

Andres Carrano


Physical copy available from RIT's Wallace Library at TA418.9.F85 B46 2012


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