Injection molding of shotgun shells
<p>In this investigation, the possibility of producing injection molded shotgun shells was explored. Also, the molding cycle and the effect of molding conditions on the mechanical properties of molded parts were investigated.</p> <p> The polymer obtained from a commercial brand of...
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Virginia Tech
2014
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| Online Access: | http://hdl.handle.net/10919/41311 http://scholar.lib.vt.edu/theses/available/etd-03022010-020047/ |
| Summary: | <p>In this investigation, the possibility of producing
injection molded shotgun shells was explored. Also, the
molding cycle and the effect of molding conditions on the
mechanical properties of molded parts were investigated.</p>
<p>
The polymer obtained from a commercial brand of shotgun
shells was analyzed using infrared spectroscopy and
differential thermal analysis. The results from the analyses
revealed that polyethylene was the main component used
in the manufacture of commercial shotgun shells.</p>
<p>
An injection mold with automatic ejector mechanism was
designed. Before attempting to construct the mold a computer
simulation was developed to predict if the "most
difficult to fill" cavity, i.e., the shotgun shell cavity,
could be completely filled with the injection molding equipment
at hand. The simulation predicted the axial distance
filled in the shotgun shell cavity within 1%.</p>
<p>
The injection molder used in this investigation was
interfaced with a PDP 8/e minicomputer; as a result the
pressure and temperature of the polymer in the mold were
monitored and the minimum molding cycle could be determined.</p>
<p>Tensile, compressive and bursting strength tests were
performed on injection molded specimens of polyethylene
and the commercial polymer. From these tests it was established
that for a molding cycle in which the plunger is
kept forward until the mold is opened and "steady-state"
cycle conditions have been established, the tensile modulus
and tensile strength at yield increase as injection pressure
and/or temperature are decreased; the opposite was true
for the same properties measured in compression. Finally,
polyethylene was compounded with additives to improve its
mechanical properties.</p> === Master of Science |
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