Call us now ! Send us an email Brookville Way Indianapolis United States

Back to Top

More Than 30 Years of Expertise
Toll Free: 800-333-4681
Phone: 317-783-4681
Call Us Today to Get Started

The Effects of Tramp Oil on Metal-Cutting Tools

Metal-cutting machine, CNC Carbide Cutter
Metal-cutting tools generate an incredible degree of heat and friction during their operation. Unless the cutting tool is protected, such factors would quickly wear down the tool, requiring more frequent replacement. To ensure safe, consistent, and efficient results, metal fabricators use what are known as cutting fluids, or coolants.

Applied to the cutting surface, these fluids help to keep the cutting tool cool during operation, thus preventing heat deformation and other structural issues. They also lubricate the cutting tool, allowing it to move through the metal more smoothly. In order to keep costs down, many manufacturers recycle cutting fluids, allowing them to be reused.

Unfortunately, however, cutting fluids often become contaminated during use by what are known as tramp oils. These oils lower the effectiveness of the cutting fluid while also resulting in a dangerous and often toxic mixture. If you would like to learn more about tramp oil and how machinists keep it in check, read on. This article will offer a useful overview of the subject.

Tramp Oil

Metal-cutting machines rely on lubricants to ensure smooth functioning for their ball screws and spindle bearings. As the machine's temperature rises, these lubricants become excessively liquefied, often running down the cutting tool into the cutting fluid. A lubricant that escapes its proper location in this way becomes what is known as tramp oil.


As tramp oil mixes together with the cutting fluid, various problems will develop. First of all, they compromise the cooling abilities of the fluid. As a result, operating temperatures at the cutting surface tend to rise. Such rising temperatures may lead to rougher cuts, as well an increased risk of warping and damage to the cutting tool.

Tramp oil reduces cooling power by preventing oxygen from mixing with the cutting fluid. As the fluid's temperature rises, some of it will become airborne, resulting in an oil mist. The oil mist will settle on floors and other nearby surfaces, reducing traction and putting workers at greater risk of slipping.

The tramp oil may also begin to smoke as the cutting fluid's temperature rises. Such smoke can have serious toxic effects if breathed in by workers. The lack of oxygen caused by tramp oil also increases the likelihood of certain types of bacteria taking up residence in the cutting fluid. Known as anaerobic bacteria, these species thrive in oxygen-depleted environments.

Many of these bacterial species pose health threats for humans. As they continue to grow, they will also break down the cutting fluid, often producing highly unpleasant gases. The bacteria also create acids that can damage the surface of the cutting tools. The longer such bacteria thrive, the greater the threat of such damage will become.


As you can see, tramp oil poses a number of serious threats for machine shops. Fortunately, two key tools exist for reducing the problems associated with tramp oil. Known respectively as coalescers and skimmers, both methods remove tramp oils from the cutting fluid. This allows the tramp oils to be safely disposed of. 

Coalescers make use of filters that push the tiny oil droplets together into larger blobs. This increases the density difference between the tramp oil and cutting fluid, causing the oils to float up to the surface of the coalescer. There they can be physically removed with an appropriate tool.

Skimmers take a different approach, using what are known as oleophilic belts. These oil-loving belts drag through the cutting fluid, attracting oils and pulling them along to a special trough. There a secondary component scrapes the oils from the belt. Isolated in this way, the oil can be safely disposed of.

Unless correctly protected against, tramp oil can wreak havoc inside of a machine shop. For more information on what it takes to protect your cutting tools from such issues, please contact the experts at CCA, Inc.


  • No categories to display

Tag cloud