Page 87 - Injection Molding Advanced Troubleshooting Guide
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8.5 Cycle Variation 71
Recovery time
Any others desired
All of these process points should be consistent over one or 24 hours. For all of the
above other than recovery time the recommended variation should be within 1%,
recovery time allows for more variation (5%) [1]. Variation in any of the key process
parameters means that the molded parts will vary over time resulting in unaccept-
able parts. See Figure 8.10 for an example of hold pressure variation which led to
variation in part dimensions.
Figure 8.10 Hold variation over 10 shots
There are various ways to check for longer-term machine consistency the easiest of
which is to track the machine actual values for specified variables. The second
method to capture long-term machine data is to use a process monitoring system to
record the data.
