First a high pressure pump sends water (up to 290 psi) in the circuits during the cooling phase. Thanks to the manifolds and specific core pins, the water is able to reach tiny areas close to aluminium.
By controlling the cooling time, the die temperature can be effectively regulated and hot spots can be removed.
Then compressed air fills the circuits and chase any remaining water back to the machine to make sure there is no water left in the die.
Finally, the whole installation is pressurized and the machine looks for any pressure drop that might be caused by a leakage.
Once it is ensured that there is no leak, the next cycle can be launched.