On single stage hydraulic presses that use a booster pump, the high pressure system (the booster pressures) must be relieved to tank before any directional valves change state. If malfunctioning, the residual pressure may shock the lower pressure side of the system (the side that is pressurized by the Variable displacement pump) and may cause o-ring leaks and hose damage.
Presses with a
single manifold use a Ram Decompression valve with an
adjustable orifice that allows for decompression speed adjustment.
If the adjustable orifice is too restrictive the system will not decompress fast enough. So, you must monitor the decompression speed and make adjustments to allow for fast decompression. The decompression systems needs to get below 250 psi in under 2 seconds. You can monitor this in the manual menu under the "pressurize ram" function. Simply pressurize the ram on a pressed cake and watch the C2 transducer feedback. It should fall off in 2 seconds or less. If it takes longer the Isolation checks may chatter as they try to open under higher pressure. Any chattering after the pressure cycle is an indicator that you need to decompress faster. If you see any hoses jumping after a pressure cycle, this is also an indicator of a decompression speed problem.
SIngle Manifold Bleeder adjustment shown here
On presses with
multiple manifolds (produced before 2018) the decompression was accomplished with a bleeder valve through a fixed orifice. This required no adjustment but may get clogged and cause issues. If you see any symptoms or o-ring failure, hose leaks or hoses jumping after pressurization, consider checking this bleeder orifice on the bleeder pilot valve. It is located behind the directional pilot inside the valve body. Removal of the pilot is necessary to see the orifice.
Presses without a booster pump (a one pump system) rely on the pump to destroke to reduce pressure. This timing can be affected by proportional valve or card settings. If you see these symptoms above check the settings on the proportional card. On newer presses the proportional card is integrated in the proportional valve, so no adjustment is possible.
