The third system is direct injection
of the finished product. Even though it cannot be said that it is an
easy technology, the injection system is by far the most convenient.
The only delicate point in the injection system is the dimensionla
control which must be very precise in the case of the sales. Sandals
and midsoles do not have this problem.
The injection of EVA break with all
the known and normally adopted methods. Infact it requires: low
temperatures in the moulds to cook and solidify the material much
smaller cavities in the moulds in respect of the final dimensions of
the product and expanding of the product in the final shape and at the
final densities when the mould is opened.
Experience teaches us that the best
system for processing EVA is the volumetric system. Allowing better
quality-especially at low specific weights. For higher specific
weights, other systems could be taken into consideration.