As is normal, it depends on whether the system is an open evaporative or a completely closed loop.

It also depends on whether the tools are made of steel or aluminium. On open evaporative systems, as long as cycles of concentration are controlled and biological control is used, almost any inhibitor will be effective while the tools are in the system. The problem comes when the tools are removed for storage. There are very few inhibitors, which will protect them once removed unless the internal water ways are dry and they will corrode internally. With Aluminium tools it is essential to control the pH to between 6.5 and 8. Aluminium is amphoteric and dissolves in both acid and alkali. Once the pH rises to above 9, it becomes self damaging and the aluminium will produce aluminium hydroxide, which being caustic in nature further damages the aluminium. There are specific aluminium inhibitors, which can be used in closed systems.

Usually, appearance and dimensional precision of the molded parts come first. Once these two factors are cleared, mechanical, thermal, chemical and physical properties are of concern. How the molding process affects those properties are important topics in the injection molding studies. Especially because crystallization is achieved during the molding, relevant properties such as optical transparency and gas permeability would depend on the processes.