Cleaning hydraulic oils in transmission productionwith a FRIESS EFR hydraulic oil filter model D8
A European automobile manufacturer operates a total of three plants for the production of gearboxes. In one of the three plants in Central Europe, a total of approx. 10,000 liters of hydraulic oil are used in various machines.
The problem
After three years of continuous operation, the number of hydraulic faults increased significantly. The maintenance team looked for the causes of the rise of hydraulic faults. When the hydraulic oil was checked in the in-house laboratory, it was discovered that the dirt content in the various machines had increased significantly. Although there were several bypass filter systems present in the company and they were used periodically, the result was still unsatisfactory.
Solution: Electrostatic hydraulic oil filter model D8
Electrostatic oil cleaning system model D8 in use
An internet search brought the maintenance staff into contact with the FRIESS GmbH factory representative. In order to check whether the electrostatic hydraulic oil filters could improve the situation, it was agreed to conduct a test. As part of this test, 40 liters of used hydraulic oil were cleaned with a model D8 electrostatic oil filtration system.
Result
The entire test lasted 23 hours. Oil samples were taken at set times and tested in the company’s own laboratory. The particle count yielded the following values:
| Sample | Date | Sampling time | MPC [dE] | Particle count / ml ISO 4406 (1999) | ||
| >4 µm | >6 µm | >14 µm | ||||
| 0* | 14.01.2015 | 10:00 | 31,3 | 1304,3 | 420,9 | 46,2 |
| 1 | 14.01.2015 | 16:00 | 12,2 | 981,8 | 398,5 | 11,2 |
| 2 | 14.01.2015 | 22:00 | 11,6 | 243,6 | 95,1 | 4,9 |
| 3 | 15.01.2015 | 04:00 | 11,6 | 110,2 | 51,3 | 1,8 |
| 4 | 15.01.2015 | 09:00 | 10,3 | 140,9 | 50 | 0,6 |
* Oil analysis / removal 10 minutes after commissioning the electrostatic oil cleaning system
- The particle count clearly shows that the content of particles >4 µm could be reduced by approx. 90 % during the cleaning process. As dirt particles in hydraulic oils are responsible for approx. 80 % of hydraulic faults, the cleaning result clearly shows that 60 - 70 % of all hydraulic faults can be avoided by using an electrostatic oil cleaning system.
- At the same time, an MPC test (Membrane Patch Colorimetry) was carried out. In the membrane test, 50 ml of oil is mixed with 50 ml of white spirit and sucked through a membrane with a pore size of 0.45 µm. This method makes oxidation products, ageing products and varnish in the oil visible.The results show a significant reduction of varnish in the oil, contributing to a more reliable operation of the hydraulic systems.