Remove Oxidation Products and Varnish, Restore Precise Press Operation
After conventional offline filtration and reservoir cleaning failed to resolve recurring servo-valve problems, an aluminium plant adopted EFR D16 electrostatic oil cleaning. Removing oxidation products and varnish allowed the cleaned oil to dissolve existing deposits, restoring precise, fault-free operation of the extrusion press.
Case Background
The Westphalian plant operates two hydraulic extrusion presses, each containing approximately 12,000 litres of HLP 46 oil. Heated aluminium billets are pressed through dies. Both pressing force and cylinder feed require precise control, making oil cleanliness essential.
Recurring Servo-Valve Failures from Oil Contamination
At an aluminum plant in Westphalia, Germany, two hydraulic extrusion presses each contained approximately 12,000 litres of HLP 46 hydraulic oil. Contamination in the oil repeatedly caused servo-valve malfunctions and failures.
An offline filtration system was installed first to improve oil cleanliness. It removed coarse particles but could not eliminate the underlying causes of the faults: microparticles, oxidation products and varnish.
During the plant shutdown, the entire oil volume was pumped out and the reservoir was cleaned internally. Large quantities of deposits, varnish and sticky oil residues were removed from the tank walls and floor. The used oil was then pumped back through the existing fine-filtration system. Even this extensive measure produced no significant improvement.
Even with effective offline filtration, oxidation products and varnish continue to form while a hydraulic system operates. Heat, oxygen and catalytic influences cause oil molecules to react with oxygen from the air. Long-chain molecules form first and are initially harmless. As they continue to grow, some combine and polymerise into resinous or gel-like solids.
These sticky, soft contaminants deposit on valves, pistons, pumps and other components, creating a brown, lacquer-like film. Because the material is soft, it can pass through conventional filter pores and remain in the oil.
More varnish particles, often containing embedded dirt, then accumulate on hydraulic components. In the worst case, the deposits prevent a servo valve’s control spool from moving correctly in its cylinder. The hydraulic system malfunctions and the valve must be replaced.
Solution: FRIESS EFR D16 Electrostatic Oil Cleaning
After consulting the oil manufacturer, the operator decided to trial a FRIESS EFR D16 electrostatic oil cleaning system.
After approximately 2,500 operating hours, an oil sample was taken and analysed. Despite all previous cleaning measures, the oil remained heavily contaminated with oxidation products. Inspection of the D16 showed that its cleaning elements had captured extreme levels of contamination.
Cleaning Results
The electrostatic oil cleaning system removed oxidation products and varnish from the hydraulic oil. Once cleaned, the oil was able to dissolve oxidation products that had already deposited inside the hydraulic system.
As a result, the surfaces of valves, pumps and other components became clean again. Moving parts were no longer obstructed, and the hydraulic system operated more precisely and reliably. After installation of the FRIESS EFR D16, the aluminum extrusion press returned to fault-free operation.
Results at a Glance
- Oxidation products and varnish were removed from the oil.
- Existing deposits inside the hydraulic system were dissolved.
- Valve, pump and component surfaces became clean again.
- Moving hydraulic components were no longer obstructed.
- The system operated more precisely and without faults.
For hydraulic-system operators:
FRIESS also provides on-site hydraulic-oil analysis and purification services. Equipment repairs and spare-parts supply are not included.
Hydraulic oil contamination causing valve problems and unstable operation in your aluminum extrusion press?
Please share your hydraulic oil grade, reservoir capacity, system pressure, ISO 4406 cleanliness level, particle and oxidation-product contamination, equipment symptoms and target requirements. Our China engineering team can recommend an EFR D16 electrostatic oil-cleaning configuration, bypass flow rate and operating schedule suited to your conditions.