Hello! Hydraulic connections on plastic molds are usually used for core pulling or reverse threading. Reciprocating cylinders are generally used for side core-pulling to solve the side core-pulling problem that the die itself cannot do. Some molds are equipped with hydraulic motors, which are rotary and used to pour the threaded parts of plastic parts. Because there are too many kinds and functions of plastic molds, your question is also general, so you have to answer vaguely. If you have any questions, you can ask them more specifically. I will give a detailed answer.