A manufacturer of rolled steel profiles uses around 4000 l coolant in order to lubricate and to cool the rollers. Because of the rolling process finest metal particles are produced and remain in the coolant. The coolant system is equipped with a belt filter, which is able to remove particles down to approx. 30 µm. In order to remove the fine particles less than 30 µm a magnetic filter was installed at a smaller coolant system. The results of this magnetic filter were not satisfying.

An article about FRIESS Magnetic filter systems in a technical journal aroused the interest of the maintenance manager. During the first meeting with the regional sales agent of Friess GmbH the maintenance team and the manufacturing manager were extremely skeptical because of the bad results with the existing magnetic filter. Because of the extremely good experience with Friess magnetic filter systems the area sales manager did not understand the bad results with the existing filter system in this application. Together with the maintenance team he checked the existing magnetic filter. Together they found out, that the cleaning of the existing magnetic filter was extremely complicated and difficult.

Difficult cleaning of magnetic filter rod

The existing magnetic filter collected the particles not only on the pipes around the magnets, but on the magnets as well. Disassembling, cleaning and assembling were extremely time consuming.

Still the poor results were not feasible. For this reason the sales manager of Friess GmbH checked the magnetic field force of the used magnets. The test result was rather poor. The magnets had a very low field force of 1500 Gauss only.

Weak magnetic field with 1500 Gauss only

The manufacturer of this magnetic filter used ineffective cheap hard ferrite magnets instead of the extremely powerful, but expensive neodymium magnets. The price of the magnetic filter was very attractive; the performance of the filter was very poor.

After installation of a FRIESS magnetic filter system FMF 420/3 with magnetic filter rods with a magnetic field force of approx. 10800 Gauss the cleanliness of the coolant was improved in short time.

High magnetic field force of appr. 10800 Gauss
Sludge collected on the magnetic filter rods is removed with a simple tool

Within one week the Friess magnetic filter FMF 420/3 removed as much steel particles out of the coolant as the old filter collected within 12 months. This shows clearly, that the magnetic field force at the outside of the magnetic filter rod is one important criterion when comparing the capacity of a magnetic filter. Of course the extremely powerful neodymium magnets are much more expensive than standard hard ferrite magnets. Because of the high field force the high efficient neodymium magnets are the much better choice. When comparing different magnetic filter systems from different manufacturer it is necessary to check the magnetic field force and the construction of the magnetic filter housing.

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