Page 283 - Injection Molding Advanced Troubleshooting Guide
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28.3 High Fill Pressure Troubleshooting 275
A common occurrence is to develop a process during the humid summer months
with the material having some moisture when processing. When winter comes and
the humidity drops the material will have a natural tendency to be dryer and as a
result will require higher fill pressures than the wetter summer-processed mate-
rial.
Nylon is very susceptible to moisture-induced viscosity variation. Because nylon
can be run over a wide (relatively speaking) range of moisture contents the differ-
ence between 0.05% and 0.2% can translate into a large difference in fill pressure.
For more information on drying see Chapter 9.
