The method is used for determining “foreign” oil (rather than emulsified one) and solids present in the working cutting fluid emulsions or solutions.
1. Equipment, materials, reagents:
2. Test preparation.
Weigh two clean dry centrifuge tubes on an analytical balance with an accuracy of up to 0.0002 g. Collect an average sample (100-150 ml of the working emulsion or solution) from the cutting fluid tank. Set a stopwatch and stir the contents of the sample container by vigorous shaking for 2 minutes. Pour the sample into two centrifuge tubes to the 10 ml mark and put them into the centrifuge slots.
3. Test procedure.
Centrifuge the sample of the cutting fluid emulsion or solution for 20 minutes at a speed of 33 rps. Then measure the volume of the mineral oil (upper layer) in millimetres and visually check for solids (bottom layer). If the solids are detected, carefully pour the emulsion off from the tube and add 5 ml of isopropyl alcohol with a pipette to flush solids settled on the bottom and the walls of the tube. Centrifuge the sample again for 5 minutes, pour the alcohol off into a test tube with solids and leave the contents of the tubes for 20-30 min. After cooling the tube with solids in the open air, weigh it using an analytical balance. The difference between the obtained results and the initial weight of the tube corresponds to the number of grams of solids in the sample volume.
Number of non-emulsified oil and solids shall be expressed in percentage. To this end, multiply the volume of the upper layer and the content of solids (in ml and grams, respectively) by the scaling factor that takes into account the dilution volume. The tests shall be conducted in parallel in two test tubes. Arithmetic mean of the two determination results shall be taken as the test result.
