We were contacted earlier this month by a client that suspected that the high volumes of waste being generated by their tramp oil skimmer systems was in fact coolant product oil. This technicians concern was that coolant he was adding to the system wasn't having the chance to emulsify and as a result, it was floating on top and being removed by their skimmer systems. He asked us to investigate.
Now this facility has a big challenge on their hands, over 100 stand alone machining centers and no central coolant delivery system. Each system is managed independently, which can lead to "huge" variability in the condition of the coolant in each over time. They are only using RI to measure and manage their coolant, and as we know, though RI is great for virgin products, it gets extremely inaccurate once the fluid gets contaminated with tramp oils and particulate, and when the emulsion stability starts to weaken.
To illustrate the limited picture RI provides as an on-going test method for concentration management of in process fluids, this chart below shows what happens if we measure the concentration of the 3 systems using 3 different concentration test methods. Over time as components deplete and contaminants build up, we see how controlling to Refractive Index alone can put the process at risk and drive costs up.
There's no one definitive tramp oil test that identifies the percentage of known oils we expect to generate from a closed system, so we used a series of qualitative and quantitative tests to estimate the relative percentage of each oil that ends up in tramp oil stream. This chart shows the percentage of coolant oil we believe is in each sample and also speaks to the relative emulsion strength of each of the sumps (ie the more coolant in the tramp oil, the poorer the emulsion strength).
Bottom line? Yes, they are losing a lot of coolant in their tramp oil removal system due to poor emulsion stability. Is it a product issue? A Fluid maintenance Issue? A mixing Issue? Likely a combination of all that (and more, the data will tell us). But because they are managing using RI only, they continue to add coolant that then gets dragged out, driving consumption and waste costs up. The challenge this plant has which is so common in today's manufacturing sector, is that they do not have the resources, systems or expertise to manage all the KPI's that impact fluid condition, and as a result, they manage what they can and use PM schedules to try and stay ahead of problems that impact production and quality. Today, as plants are working hard to meet production demand, often even those PM's are no longer possible, making this drag out problem even worse.
We are trying to let them know there is a better way. :) (ie Z-TPM)