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The effect of heat transfer coefficients and thermal conductivity on polymer processing simulation.

Dawson, A; Urquhart, J M; Rides, M (2008) The effect of heat transfer coefficients and thermal conductivity on polymer processing simulation. NPL Report. MAT 17

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Abstract

The effects of heat transfer parameters key to industrial processing have been identified
via polymer injection moulding process simulation. Moldflow finite element analysis
software has been used to simulate injection moulding of components to investigate the
relationship between injection moulding processing conditions and the effects of
material properties on the moulding process. The effects of core and cavity side heat
transfer coefficients, thermal conductivity and component thickness upon the injection
moulding cycle time have been examined. Time to freeze for a moulding decreased
with increasing polymer thermal conductivity, this effect becoming less pronounced
with decreasing moulding thickness. Maximum injection pressure for a moulding
increased with increasing polymer thermal conductivity with this effect becoming less
pronounced with increasing moulding thickness. For a component, time to freeze
decreased with increasing average heat transfer coefficient, although an effective lower
limit to time to freeze was reached when core and cavity heat transfer coefficients
values were set at 10,000 W/(m2.K) or above. These values for core and cavity heat
transfer coefficients also set an effective upper limit for the maximum injection pressure
for a component. Setting both core and cavity heat transfer coefficient values at 500
W/(m2.K) gave the lowest times to freeze and the lowest maximum injection pressures
for all thicknesses. Setting the heat transfer coefficient values to 4,000 W/(m2.K) and
6,000 W/(m2.K) for core and cavity or cavity and core sides, respectively, produced the
shortest time to freeze and highest maximum injection pressures of all the cases where
the heat transfer coefficients were set at different values. The study has helped to
improve understanding of the heat transfer taking place during injection moulding.

Item Type: Report/Guide (NPL Report)
NPL Report No.: MAT 17
Subjects: Advanced Materials
Advanced Materials > Polymer Rheology
Last Modified: 02 Feb 2018 13:15
URI: http://eprintspublications.npl.co.uk/id/eprint/4117

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