Page 104 - Injection Molding Advanced Troubleshooting Guide
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9.4 Material Handling 89
Placement of the drying hopper on the feed throat of the machine (see Figure
9.5):
This will eliminate any issues with external transfer of the material from the
drying hopper to the machine hopper. This works reasonably well with small
hoppers but as they become larger cleaning them out during material changes
can be more challenging.
Figure 9.5 Drying hopper mounted on a molding machine
When dealing with materials that are extremely hygroscopic remember that how
they are stored will impact drying time. Nylon stored in an open container in hot
humid environments may require 10 hours or more to fully dry as compared to the
2–4 hours drying required for material from a fresh foil sealed bag. Try to keep the
opening for the material loading tube as small as possible and when finished roll
the bag up to try to seal against the environment.
Never forget that the drying time recommended by the material supplier accounts
for average values. When drying very wet material the extra required time must be
accommodated prior to molding startup.
