23 June 2015, 08:00
Rexroth offers a new hydraulic fluid rating procedure which is better suited to the increased requirements on modern hydraulics. New test cycles show wear properties under realistic conditions and increase operational reliability.
Higher operating pressures and significantly increased power density: hydraulic performance has greatly increased again in the past years. This also places higher requirements on the hydraulic fluids used which have a decisive influence on the wear properties of hydraulic components. For this reason, Bosch Rexroth offers fluid and additive manufacturers a newly developed rating procedure for hydraulic fluids which realistically reflects and reproduces the new requirements. It goes far beyond the minimum requirements of the corresponding fluid standards. An important result: The current minimum requirements are inconclusive. On the one hand, the tests show fluids which do not cause any wear, even after 500 hours. On the other hand, hydraulic fluids can cause significant damage after less than 100 operating hours.
The relevant standards, DIN 51524, ISO 15380 and ISO 12922, outline minimum requirements for hydraulic fluids. However, they do not sufficiently reflect the technical developments in high-performance hydraulics and the suitability of new hydraulic media and additives. With a new, scientifically standardized evaluation procedure, Bosch Rexroth tests the behavior of fluids and the interaction with the core component pumps and motors under realistic operating conditions. "The results show that suitable fluids substantially lengthen the service life of hydraulic components and therefore significantly lower the probability of failure," emphasizes Karl-Heinz Blum, Basic Development Fluids at Bosch Rexroth. The test procedure was initially developed and validated for A4VG series hydraulic pumps as well as A6VM series hydraulic motors in closed circuits. Rexroth offers this evaluation service to fluid manufacturers and, as a result, is compiling a steadily growing database of hydraulic fluid properties under real conditions.
The evaluation procedure, which is described in the Rexroth data sheet no. 90235, is suited to all mineral-oil-based hydraulic media, environmentally acceptable media, as well as fire-resistant, water-free hydraulic fluids. Various test procedures include testing the fluids at high pressures in different cycles over several hundred operating hours, both at high temperatures and at low viscosities.
TAccording to standardized methods, Rexroth is able to make statements regarding the interactions of fluids and components, wear properties and material compatibility. Fluid analysis at the start of, during, and at the end of the test procedure makes it possible to make statements concerning the fluid's properties throughout the duration of the test. "In this way, machine manufacturers and operators can select the fluids best suited for their application and significantly increase operational reliability," confirms Karl-Heinz Blum.
Source: Bosch Rexroth