Primož Cizl, dipl. inž., doc. dr. Franc Majdič univ. dipl. inž., Univerza v Ljubljani, Fakulteta za strojništvo

Abstract:
Hydraulic fluids made from fossil fuels are a major ecological burden despite their good corrosion and wear properties. Water seems to be the future of hydraulic fluids, but due to lack of interest and special equipment, it is still underestimated. We have sustainably tested a proportional directional control valve made by three-dimensional printing using water as hydraulic fluid. We observed the change in internal leakage as a function of the number of cycles (from the initial state, shown in Figures 6 and 7, to the final state of the body and spool, as shown in Figures 13 and 14). The measurement results, shown in Figures 15, 16 and 17, are unexpected and difficult to explain. The final stage of wear of the spool, i.e. small particles of the worn spring, were clearly visible. Corrosion erosion is the major problem in performing the sustainability test as proved by the attached pictures. ​

Keywords:
water hydraulics, sustainability test, internal leakage, proportional valve, corrosion, wear