The current process for manufacturing an extrusion blow
moulded part via purely experimental techniques is traditionally
sequential in nature. It consists of taking the mould as
provided by the customer, modifying and installing it, and
then preparing the die. Extrusion blow moulding processing
conditions are roughly estimated; then, the part is fabricated.
Once fabricated, the part is inspected to verify whether or not
it meets the required specifications within the tolerances. In
the case of the dumbbell, part weight and thickness distribution
targets were given. To achieve these targets, an iterative
process was used where, for each parameter, a number of process steps were repeated including fabrication of the part
during every iteration. This design process is shown in Fig. 5.
Because the parameters are not simultaneously optimised,
there is a looping effect for each target parameter, which
makes development times very long. The numbers given in
each box represent the task numbers.