Does your coolant life seem to get progressively shorter and shorter? Do you dump your sump and recharge it with fresh fluid expecting to get another 8-12 months of coolant life, only to have it go rancid yet again 6 months later? What is the problem and why does the fluid keep going bad? It has got to be the coolants fault… right? Not necessarily. How thorough were you in cleaning your coolant system? Did you remove the coolant sump, chip conveyor, pumps and screens and really clean them? In addition, did you use a recommended machine cleaner from your fluid manufacturer? If the answer to these questions is no, then you may have a Bio-Film problem. So what is Bio-Film and where does it come from?
Bio-Film is a mucus like matrix (Mucilaginous/Glycocalyx) comprised primarily of sugars, called Extracellular Polymeric Substance. Bio-Films are sessile (stationary) and are comprised of various species of bacteria which have significantly different properties from free-floating (Planktonic) bacteria. This community of microbes communicates biochemically within the Bio-Film matrix, which gives it the capability to perform different tasks beyond the capability of any individual bacteria member. An example of the type of synergism between different bacteria species within a Bio-Film community is sited from Dr. Frederick J. Passman, Metalworking Fluids-Second Addition. “What one species of bacteria, (Pseudomonas aeruginosa) produces as a waste product, (Sulfur and Secondary Metabolites), feeds and enables another species of bacteria (Desulfovibrio desulfuricans) to survive. In turn the D. desulfuricans creates conditions that enable P. aeruginosa to attack metalworking fluids (MWF) molecules at a maximum rate.” Here are two picture examples of Bio-Film growth stages and what it can actually look like.
A recent study sited in TLT Magazine showed the Polysaccharide film produced by bacteria, was measured to have the holding strength of 70 Newton’s; this is equivalent to super glue. This sticky Polysaccharide film protects the bacteria within the Bio-Film community, thus making most biocides ineffective against Bio-Films. Bio-Film needs to be addressed when the sump needs to be changed either by physical scrubbing or by using a pressure washer with hot water or steam capability. In addition, machine cleaners proven to dissolve Bio-Film should be used, or the end results will be the same - subpar coolant life and higher fluid costs. The scope of this article doesn’t cover the additional costs and damage that Bio-Films cause to the machines and also the health hazards and costs associated due to high amounts of bacteria growth.
Stay tuned for more useful coolant related tips, from The Coolant Guy!
Brett Reynolds, CMFS
Brett Reynolds, “The Coolant Guy” works for Blaser Swisslube Inc.
If you would like more useful information regarding metalworking fluids, or would like to find out more information about Blaser metalworking fluid products,
Please contact Brett at 801-722-4095 or via
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