Metalworking fluids provide a warm and nutrient-rich environment for growth of bacteria and fungus. Once microbial growth is established it can contribute to the breakdown of the metal working fluid emulsion and consequently its ability to lubricate metallic surfaces. Microbes also lower the fluid’s pH, leading to corrosion of tool parts and staining of wetted metal surfaces. Uncontrolled growth can lead to a build-up of biomass that clogs fluid distribution systems leading to tool failure and shutdown.
Aside from productivity concerns, contaminated fluid can also pose a serious health risk for employees. These risks are well-documented by the Center for Disease Control (CDC), the Occupational Health and Safety Association (OSHA), and many other health and labor boards. If not kept under control, significant health hazards such as respiratory distress, skin rash, eye and throat irritation, and even hypersensitivity pneumonitis (HP) in rare cases. While fluid management has improved over the years, the health risks inherent to poorly managed metalworking fluids is not always fully understood.
The first step in the control of microbial contamination is the detection/quantification of the contaminant. Dip slides and pour plates have typically been used for microbial detection but both methods require 24-48 hours for results to be gathered. The resulting delay in action may allow for undue wear on manufacturing equipment and the establishment of biofilm within the fluid delivery system. ATP detection using bioluminescent enzymes is an attractive alternative to direct microbial counting but direct analysis of metal working fluids, like most oil-containing liquids, is difficult with conventional bioluminescent systems since the enzymes are often denatured by the oil. This often leads to false negatives.
LuminUltra’s Quench-Gone Organic Modified (QGO-M) test protocol uses a significantly more advanced and robust reagent system than conventional ATP test methods and is able to quickly and easily separate microbes from the oil in the sample. Light-quenching tendencies that are inherent to organics-laden fluids are negated through optimized protocols and sensitivity can be easily increased simply through additional filtration of sample if the need arises.This protocol has been proven to provide reliable results in clean fluids as well as highly contaminated ones and everything in between. As such, it is recognized under ASTM standard E2694.
For more information, visit the Metalworking Fluid section of LuminUltra Academy.