Principle of stretching-blow moulding of a bottle:
A preform (rough casting) is placed in the mould by a transfer arm; the stretching rod goes down.
The stretching rod stabilises the preform as the mold closes and the transfer arm goes away.
The rod goes down and pulls the plastic downwards (stretching); in the meanwhile, pressured air (about 5 bar, 72.5 psi) stretches the preform radially (preblow). This ensures the mechanical resistance of the bottle by bi-orientation of the polymer chains.
Blowing (pressured air up to 40 bar, 580 psi).
The air is released; the transfer arm takes the bottle, the mould opens.
The rod goes up back in position, the transfer arms takes the bottle away while a new preform comes.
Own work
Cdang; Samuel Dupré for the advice