Checklist for water-miscible cooling lubricants

What should be considered?

General requirements

The cooling lubricant concentrate and the containers into which it is filled should be protected from frost and direct sunlight and not stored outdoors.

Requirements for the mixing water

There are different types of water used in the processing industry. These include tap water (drinking water), deionized water (osmosis water), well water and processed water. In order to achieve optimal service life of the water-miscible cooling lubricant, we recommend paying special attention to the following when mixing:

•    mixing water should have drinking water quality and germ saturation of max. 10² CFU/ml
•    water hardness should be 5° dH - 30° dH for emulsions and 10° dH - 30° dH for solutions
•    never use heated water, temperature <25 °C
•    pH-value: 6 to 9
•    nitrate content: < 50 ppm (target: < 25 ppm)
•    conductivity: µS/cm: max. 1000 – 1500
•    chlorine content: < 250 mg/L (target < 50 mg/L)

Mixing of the emulsion or solution

It is best to have water outside the machine and in clean containers into which the cooling lubricant concentrate is added. If using a mixing device make sure that it is in good condition and not damaged or altered. It is important that you first fill the water in the tank and then add the cooling lubricant. Otherwise you will have a reverse emulsion and the water will quickly separate from the lubricant.

Check of the water-miscible cooling lubricant during use according to TRGS 611

An odour and visual inspection should be performed continuously during the operation of your machine. When the cooling lubricant starts to smell, this is often an indication that it is contaminated by bacteria. Check to ensure there is no fungal growth on the coolant surface.

A routine check of the concentration with a hand refractometer (according to the manufacturer's specifications) is mandatory for optimum processing and protection of your machine, components and workers using the machine. If the concentration is lower than the level stated in the product information, add cooling lubricant concentrate. If the concentration is too high, remove part of the emulsion/solution and top up with water. The pH value (according to manufacturer's specifications, see product information) and the water hardness should be checked to ensure they are within the range of 5° dH - 30° dH for emulsions and 10° dH - 30° dH for solutions. The nitrite concentration should not exceed 20 ppm according to TRGS 611. If your machine has a leakage or if hydraulic oil/gear oil gets into the cooling lubricant, you can remove this foreign oil entry using a foreign oil separator or an oil skimmer. Entry of foreign substances (other lubricants, cleaners,...) should be avoided. If required, you are welcome to send a sample to our laboratory, which is analysed using the latest technical equipment.

Before refilling

If you have to change your cooling lubricant, a system cleaner needs to be added (according to manufacturer's specifications). Further operation is recommended, for emulsions approx. 24 hours, for solutions approx. 8 hours, so that the system cleaner reaches all points, hoses, pipes and pumps of your machine and removes bacterial and fungal infestation. Afterwards you can have the old emulsion or solution pumped out by a disposal company near you. The necessary waste code can be found in the respective safety data sheet in section 13. Once the machine is emptied, we recommend flushing it with clear water several times. Then the machine can be cleaned and filled with clean lubricant .

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