Why tramp oil is a chronic issue and what you can do about it

Learn why tramp oil and solid particles are a problem in metalworking.

DATE 2024-02-27


If you work in metalworking or manufacturing, you’re familiar with tramp oil, or as some call it, the Monday odor. Basically, this catch-all term refers to any unwanted non-soluble, hydrocarbon-based substance that contaminates the metalworking fluid. It’s easy to tell if you have an issue with tramp oil because of that distinctive (and unpleasant) rotten-egg odor in the machining shop.


Machining processes generate a significant amount of heat. So if you’re cutting metals, the machinery requires lubrication of components such as bearings, slides and ball screws to prevent burning or smoking. Lubrication oil or hydraulic oil helps to keep your workpiece at a stable temperature, prevent rust and maximize its lifespan.


Over time, however, these oils migrate into the machine sump, mixing with and contaminating the metalworking fluid, including coolants. Oil-based rust prevention coatings on components, as well as degreasing solutions for components or surface coatings, can also cause tramp oil contamination.


And it’s not just a foul smell you have to worry about. Tramp oil can reduce the efficiency of your metalworking fluid, impact the performance of your machinery and foster the growth of bacteria and fungi, which can damage tools and sicken workers.


Why tramp oil and solid particles are such a big problem


If tramp oil isn’t separated and removed, it becomes a breeding ground for bacteria and fungi (hence, the foul smell), which can cause serious health hazards for employees such as respiratory and dermatitis issues—not to mention an unpleasant work environment.


It also affects the performance of the metalworking fluid. For example, contamination diminishes the ability of a coolant to reduce temperatures and the growth of bacteria lowers the pH, which in turn diminishes lubricity. Microparticles can also contaminate the fluid, which could result in a sand-blasting effect on components.


This means tools wear down more quickly, requiring more frequent repairs, shortening their lifespan and leading to production inefficiencies. It can also lead to decreased precision when using those tools, which can affect product quality.


Benefits of removing tramp oil and particles


By cleaning your fluids, you can extend the lifetime of those fluids and improve the working conditions for employees. It also reduces the environmental impact of industrial processes and enables more responsible use of natural resources.


“By using the right tramp oil purification process and equipment, metalworking operations can see a 40 to 80 percent reduction in coolant purchases and a corresponding decrease in disposal costs,” reports Production Machining magazine.


Metalworking fluids should be cleaned and replaced at regular intervals (the better the

cleaning, the longer those replacement intervals can be). While this reduces the cost of replacing fluids, it also results in less downtime and maintenance. Changing coolant, for example, typically results in two to three hours of downtime (plus labour costs).


How Alfa Laval can help


There are two types of tramp oils: Free tramp oils float to the surface, while emulsified tramp oils mix into the metalworking fluid. While tramp oil is inevitable in most machining processes, cleaning your metalworking fluids from tramp oil and particles on a consistent basis can save money and improve worker safety.


Depending on your requirements, there are several conventional methods for removal of contaminants including filtration, skimmers, coalescers and centrifuges (or a combination of methods). For example, centrifugal separators are well suited for difficult conditions such as large cleaning volumes or a temporary high influx of oil. A centrifugal separator from Alfa Laval removes both tramp oil and solid particles down to 3 microns at a 70% removal rate in one simple step.


Learn more about the four most common cleaning methods or talk to one of our Alfa Laval experts.

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