3 years ago

MDA Technologies 4/2016

MDA Technologies 4/2016


ASSESSING FLUIDS CLASSIFICATION ACCORDING TO DIN 51524 The requirements of hydraulic fluids on mineral oils basis are regulated in Germany by DIN 51524. Amongst other things we distinguish between HL, HLP, HVLP and HLPD. HL stands for hydraulic oils with active substances to increase corrosion protection and durability, which can be used up to 200 bar. DEVELOPMENTS OVER THE LAST FEW YEARS The demands and efficiency in hydraulics have increased significantly. The power to weight ratio of axial piston pumps and motors for example has more than doubled over the last few decades. Over and above this the level of pressure in numerous applications has risen considerably. This improved performance places demands on the hydraulic fluids used much more than before. Hydraulic fluids in combination with the operating conditions have a decisive influence on wear behavior and in this way on the life expectancy of hydraulic components. HLP stands for hydraulic oils (pressurized fluids); hydraulic oil that provides increased wear protection: DIN 51524, Part 2 MACHINE ELEMENTS HLP: like HL, however with high pressure additives, also for pressures above 200 bar. HVLP oils in addition have improved viscosity. HLPD mineral oils in comparison to HLP oils offer additional detergent properties. STANDARDS ARE NO LONGER UP-TO-DATE The minimum requirements valid to-day in the corresponding DIN 51524 standards for hydraulic fluids based on mineral oil, ISO 15380 for environmentally compatible hydraulic fluids as well as ISO 12922 for hydraulic fluids with low flammability, do not however reflect these increased demands. Up until now however mechanical equipment manufacturers have only been able to rely on fluid manufacturer details when choosing their fluids, and chose suitable fluids by trial & error. One mistake here threatened to shut down the machinery and bring high warranty claims. MDA Technologies 4/2016

PROBLEMS WITH TRIAL & ERROR The minimum requirements of standards are not sufficiently conclusive for modern hydraulic applications. And so tests demonstrate there can be large differences between the effectiveness of two fluids, although both fluids meet the standard. Whilst Fluid 1 already leads to distinct wear on the pump and motor after barely 150 hours, even after 500 hours Fluid 2 displays no negative effect on the components. About Bosch Rexroth term 145 h term 510 h Bosch Rexroth is a worldwide leading supplier of hydraulics, electric drives and controls, gear technology, linear motion and assembly technology. With locations in over 80 countries and more than 31,100 associates, the company generated sales revenue of approximately 5.4 billion Euros in 2015. The company has a global expertise in the market segments of Mobile Applications, Machinery Applications and Engineering, and Factory Automation to develop innovative components as well as tailored system solutions and services. PRACTICAL FLUID ASSESSMENT Based on internal tests, Bosch Rexroth has developed a scientifically based and standardized fluid assessment process named Fluid Rating – including an internally standardized practical test with several hundred hours of operation under different conditions. In this way fluids and their physical interactions with pump and motor are examined in practice. This is suitable for all hydraulic media on mineral oil basis and related types of hydrocarbons, environmentally compatible media, as well as highly inflammable, water-free hydraulic fluids. Manufacturers of lubricants and additives can use this process we describe as Fluid Rating in order to independently assess the effectiveness of their hydraulic fluids. At of lubricant and additive manufacturers can register for the assessment process. Rexroth then requests the characteristic technical values of the hydraulic fluid to be assessed from the manufacturer, examines them for plausibility and has the conformance with standards confirmed. The additional requirements included tighter norm parameters and specific fluid and pump tests. These show the suitability of the hydraulic fluid for defined Rexroth components. If the hydraulic fluid fulfills all requirements, it is accepted into the Bosch Rexroth Fluid Rating List which Rexroth uses internally and in future will also provide to the company’s customers. MDA Technologies 4/2016