Three contaminants of Metal Working Fluids

Water-based metalworking fluids are essential for effective metalworking processes. They contain a blend of crucial components, including pH buffers, lubricants (such as paraffinic, naphthenic, ester, and Extreme Pressure), emulsifiers, corrosion inhibitors, microbicides, anti-foam additives, and water.

By combining these components in the right ratio (formulation), a stable concentrate is produced that can be used in the appropriate application. However, the fluid is still susceptible to environmental factors and contamination that can diminish its effectiveness.

It’s important to address any threats to the metal working fluid’s efficiency early on, to avoid the disposal of valuable products. At the end of the day, maintaining the quality of the fluid is essential for the smooth operation of metalworking processes.

Microbial contamination:

• Tramp oil:

Tramp oil refers to unwelcomed hydrocarbon-based substances (hydraulic/slideway oils). These substances contaminate metal working fluid emulsions and can often lead to anaerobic bacterial growth, which means bacteria can thrive without oxygen.

Bacteria in these emulsions produce organic acids which neutralize the pH buffer additives present in the product and lower the pH of the fluid. Consequently, a low pH value promotes corrosion and further bacterial growth.

Corrective action: To prevent further degradation of the metal working fluid, it’s crucial to take corrective action. One long-term solution would be to fix any persistent machine oil leaks. However, this is not always a simple task. A more immediate solution involves removing any de-emulsified leak oil from the surface of the fluid to prevent the creation of an anaerobic environment. Adding a System Cleaner additive to the fluid can also be effective in increasing the fluid’s alkalinity and neutralizing existing bacteria.

• Organic matter:

Organic matter that contaminates the metal working fluid emulsion could be food, saliva, the operator’s skin, cigarette butts, and the like. The contamination serves as nutrients for bacteria to convert into waste and organic acids which, as discussed in the previous point reduces the alkalinity (corrosion prevention) in the emulsion.

Corrective action: Firstly, keeping a clean and safe work environment is very important to ensure that no organic material is introduced into the metal working fluid. Secondly, staff and operators should undergo relevant training regarding housekeeping. Finally, removing the organic material from the fluid and adding a System Cleaner additive to the fluid (increase alkalinity and neutralize bacteria) would work to prevent further fluid degradation.

• Water:

When it comes to metalworking processes, water plays a crucial role. It’s used to blend with the metal working fluid concentrate and create an emulsion that provides lubrication, cooling, and particle removal, as well as protection against corrosion and other damage. However, depending on the source of the water, it can contain unwanted microbes such as bacteria, fungi (including yeast and moulds), and other contaminants.

Fungal contamination can be particularly problematic, as it can create biomass and toxins that can undermine the effectiveness of the fluid. If left unchecked, the biomass can grow into a mat that needs to be physically removed after being killed with a fungicide. If not removed, the dead fungi can provide nutrients for bacteria to grow, leading to further contamination and potential damage to machinery.

Corrective action: Do not add water straight to a tank containing metal working fluid emulsion. Instead, use a lean pre-mix of 2.5 – 3.0% metal working fluid and water to boost the machine’s fluid.  Using a lean pre-mix will neutralize any incoming bacteria and fungi spores so no build-up of microbes occurs. Use treated water (Reverse Osmosis with UV light) instead of Municipal water to mix with the concentrate.

To conclude, metal working fluid’s play a vital role in the metalworking process,  and therefore contamination threats should always be carefully considered. Additionally, when working with these fluids, researching effective preventative and corrective measures is crucial.

This is where we come in. At CSI, we’re the experts you need for all your metalworking fluid and lubricant needs. Our team boasts an infinite amount of knowledge and expertise in this sector, so you can trust us to have the right solutions for your specific chemical requirements.