Many older-generation hydraulic presses and stamping machines employ simple on-off control of two position hydraulic valves to extend and retract the hydraulic actuator that does the work. In such machines, precise control of the ram position may not be a primary requirement, but velocity control can turn into a big issue. Depending on the application, the use of discrete (on-off) hydraulic valves could impact the quality of production units, and may actually be hazardous to a machine’s health...
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