Monitoring Wear of Spool Valve in Fluid Power Control System

Solid particles such as sand and wear particles contaminated in the hydraulic oil are considered the main cause of the wear of moving surfaces like spool valves and internal surface of hydraulic cylinders. The present work aims to specify the relationship between sand particles contaminated in the hydraulic oil and the wear mechanisms by examining wear particles retained by the oil filter disassembled from the hydraulic system. The photomicrographs of wear particles provided specific information about the severity of wear. The visual inspection of the surface of spool by optical microscope described wear mechanism, detected the transfer from one wear mechanism to the other and identified the effect of sand particles on the severity of wear. It can be concluded that wear particle analysis for fluid power system gives specific information about system condition, where examination of the wear particle morphology will reveal the wear mode such as severe sliding wear and solid contaminants induced wear. During sliding of spool valve, abrasion can be considered the major type of wear. Abrasion leads to scuffing and scoring that may cause high increase in sleeve clearance. Besides, sand particles are critical cause of excessive spool wear. Proper design and maintenance of the filtration system is essential. The mechanisms that largely influence the wear in the spool and sleeve include abrasion, adhesion and scuffing as well as chemical corrosion. Both of these mechanisms can operate independently or together, depending on the operating variables. It was found that during system operation under severe dusty environment, the spool and sleeve are the most intensively worn parts.