FMEA for Hydraulic Systems

We define hydraulic system functions at the machine level and decompose into subsystem functions. Failure modes include: pump flow loss from wear, pump seizure, pump cavitation erosion, proportional valve spool sticking, proportional valve solenoid failure, directional valve internal leakage, relief valve set pressure drift, check valve leakage, cylinder piston seal bypass, cylinder rod seal leakage, accumulator bladder rupture, accumulator pre-charge loss, hose burst, hose external leakage, filter element bypass, filter housing crack, and cooler tube leak. Severity ratings account for machine damage potential, production loss, and safety consequences (especially for press and lifting applications). Occurrence ratings are linked to fluid cleanliness level per ISO 4406—achieving tighter cleanliness targets directly reduces occurrence scores for contamination-sensitive modes. Detection ratings evaluate installed monitoring: pressure transducers, flow meters, fluid sampling capability, and filter bypass indicators. RPN-driven task selection assigns fluid management tasks, filter maintenance, component monitoring, and accumulator testing. The FMEA demonstrates the ROI of improved filtration by quantifying its effect on system-wide failure mode occurrence.