The application of an increasing pre-blow pressure during
mould clamping was modelled so as to represent the
real process. The operating conditions and simulation results
obtained for different die diameters, and the results of the
three trials are shown in Table 4. Reducing the die diameter
from 7 cm to 5 cm, even at the minimum die gap opening of
0.1cm reduced the dumbbell weight to 201.4 g, approximately
25 g over the desired weight. In trial 3, the die diameter was
then reduced to 4 cm with a constant die gap opening of 0.2 cm.
The predicted weight was 195.7 g. As the predicted weight is
now relatively close to the desired weight with a die diameter
of 4 cm, simulations can now be performed looking at changes
in the die gap opening.