Page 4 - Coolant - Houghton Training
P. 4
Metal Working Fluids - Chemistry
Once the pH goes too low, it is likely that they will lose their performance qualities and
are no longer a useful tool. It will lose its anti-rust capabilities, bacteria will grow even
more quickly, and the emulsion itself may split out into its constituent components. A
split emulsion can also be caused by water hardness, if in excess of 450ppm of
carbonates. Hardness can cause coolant to foam excessively and helps the tramp oils
form a grease layer on the coolant surface, which is difficult to skim.
The chemical make-up of the coolant can also be affected by the metals that are
introduced during the machining process. Ionic activity between the positive atoms of
the metals and negative atoms in the coolant can cause premature failure as the
emulsion starts to break. The amount of metal chips in the coolant system, as well as
their size, can affect the emulsion in as little as 15 minutes (on a grinding application).
