1. Ensure that the workpiece pressed by the upper end of the piston rod of the nitrogen spring of the mold is completely attached to the piston rod when moving, with sufficient hardness.

2. Avoid placing the nitrogen spring in an exposed and high heat source environment.

3. Avoid that the contact surface of the workpiece at the top of the piston rod is not perpendicular to the axis of the piston rod, resulting in unbalanced load.