Pressure velocity (PV) is a fundamental property of all plastics, and is specific to the composition of the plastic. PV for a lead screw application is a calculated value based on load and surface speed of the interface between the leadscrew and nut. Manufacturers now have the ability to mold in reinforcement and lubrication materials which allow loading of polymers to far exceed the capabilities of plastic nuts in the past. These factors have changed the way that PV is calculated by engineers, and allow leadscrew assemblies to enter into applications, where only a few decades ago a leadscrew and nut would never be successful. The following will explain PV and why it is important, basic example for calculating PV in a leadscrew application, and what happens when the PV of a material is exceeded.