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12.7 Cavity Fill Balance Study 107
12.7 Cavity Fill Balance Study
Evaluating cavity fill balance is an easy study to conduct. Simply run a fill only
shot ensuring that the fullest cavity is still short, and then weigh the parts from all
cavities to determine the heaviest and lightest cavities. Cavity fill balance can be
expressed by the following equation:
heaviest cavity − lightest cavity ×100 = % imbalaance (12.1)
heaviest cavity
Depending on the requirements of the parts being molded the industry standard
for cavity fill imbalance is less than 3–5%. If cavity imbalance is higher than 3–5%
the balance problem must be dealt with to provide consistent parts between all
cavities. Figure 12.7 is an example of a spreadsheet form for conducting a cavity
balance study.
Figure 12.7 Cavity balance worksheet
