Big car producers use die casting machines in order to produce components for engines and gearboxes. Up to three temper devices, depending on the size of the mould and the machine, are used to cool the mould. The cooling water flow rate in the temperature control units gets checked with the help of little flow meters with turbine wheels. During production, often false alarms happened because of low cooling water flow. Result was loss of production. In a detailed inspection the maintenance team found out, that the flow of cooling water was correct. Reason for the fault indication was subtle dirt particles, which got stuck in the turbine. Thereby the turbine got hampered and the result was not correct anymore. For this reason, the control units needed to be replaced after 2000 h of operation. Normally those turbines are able to work over 10 years. All in all the cost for the exchange of turbines exceeded 40,000.00 € each year.

The maintenance team and the producer of the control units were looking for possibilities to reduce the high operation costs. They were confident that cleaning the water will reduce the operation costs. By looking in the internet the producer got in contact with the company Friess GmbH. After the first analysis, two magnetic filters FMF 240/1 HT were installed in the cooling water system of a die casting machine. After two weeks of operation the magnet filter were opened for the first time. Although the cooling water did not look very dirty, the magnetic filter rods were strained with ferritic particles. After two more weeks of use the magnetic filter rods were contaminated with particles again. Even though it is a closed circuit it is obviously, that the system always produces new particles. The cause for the particle load is corrosion in the cooling channels of the moulds.

Because of the constant removal of ferritic particles the cooling water is way cleaner than before. Now, the turbines in the temperature control units are much longer than 2000 h in use. A retrofit of magnet filters in the other cooling water systems is provided.

Magnetic filter rod with collected particles from the cooling water circle
Ferritic particles between 2 µm and 100 µm from the cooling water

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