Monn, J., Raffio, T., and Kissock, K., "Energy Efficient Mechanical Press and Hydraulic System Operation," SAE Technical Paper 2012-01-0326, 2012, doi:10.4271/2012-01-0326.
Mechanical stamping presses and hydraulic systems consume a large portion of their rated power while idle. This paper discusses a method to control press and hydraulic system operations with the goal of reducing energy consumption during idle. First, key equations relating fraction of rated power to load are derived using measured data. Next, these relations are used to determine the “energy payback period”-the length of an idle period required to justify a system shutoff. It is shown that energy use is reduced when the machines are turned off if they will idle for a period of time longer than their energy payback period. This is demonstrated in two case study examples from industry.