by
Honor J. Passow
S.B. in Mechanical Engineering
Massachusetts Institute of Technology
1990
Submitted to the Department of Mechanical Engineering
in Partial Fulfillment of
the
Requirements for the Degree of
MASTER OF SCIENCE IN MECHANICAL ENGINEERING
at the
MASSACHUSETTS INSTITUTE OF TECHNOLOGY
February 1993
ABSTRACT
The objective of this study was to determine the effectiveness of
imposed vibrations at increasing the flow rate (or effectively decreasing
the viscosity) of highly-concentrated slurries like metal injection molding
(MIM) feedstocks, under typical MIM conditions. The slurries used
simulated a typical MIM feedstock in viscosity, density, and solid volume
fraction. The slurry was forced through a capillary tube at estimated
shear rates from near zero up into the range used in MIM. The capillary
was vibrated at frequencies from 10 to 5000 Hz. There were only a
handful of significant improvements in flow rate with vibrations of the
capillary. These were only at very low shear-rates, where, unfortunately,
the experimental errors were large. The data indicates that there
may be significant increases in flow rate at sufficiently low shear rates.
A simple model predicts the trend in flow improvements as shear rate decreases,
but the magnitudes of the predictions are far lower that the data.
More experimentation is needed to confirm the trends indicated in this
study and to further investigate the model's validity.