Machinists and those linked with the metal cutting industry recognize the significance of having a great cutting oil. There are distinct types of fluids needed in the cutting process. Oils, oil/ water emulsions, pastes and gels are just a few cutting fluids to deal with.
Cutting oils have established properties needed for the job. 1) The most important is having a fluid that will keep the workpiece at a stable temperature. Machinists avoid hot or hot and cold temperatures. 2) Fluids that maximize the cutting tip is desirable. Machinists want to minimize tip-weld. 3) Workers who handle the fluid should have a high degree of safety around the substance. Toxicity, bacteria, fungi dangers should be avoided. Proper disposal of the fluid after use should be the machinists concern. 4) The cutting oil should help to prevent rust on the machines and individual parts.
There are a few different cutting fluids used by industrial machinists. Synthetic oils combine the best properties for working with metals. Rust inhibitor, tolerance, ability to work with varied metals, thermal breakdown, and safety to the environment are attributes of a good cutting fluid. Good cutting fluids contain several elements to do the right job.
- Mineral oils have been in use since the 19th century. Petroleum based, these minerals will vary from sulfur-rich and thick for heavy industrial to light, clear oils.
- Semi-synthetic coolants are micro-emulsions of water and mineral oil. These synthetics have been in use since the 1930s. CNC machine tooling uses this coolant of emulsified oil into a larger portion of water with detergent.
- Synthetic coolants are produced by chemical manipulation and has been used by machinists since 1950. These fluids are generally, water-based.
Cutting fluids can take the form of paste or gels. Metal sawing is an application that runs the paste down the blade for lubrication. Other forms of cutting fluids can take the form of aerosol. There are a few inherent problems using aerosol. The first is errant spray being hazardous for the workers. The second problem is an uneven delivery. These problems have been disposed of by implementing directional tubes aimed precisely at the workpiece.
There are several considerations for worker safety. Exposure to various cutting fluids have been linked to problems such as heart disease. The problem for workers is the fluid splatter that will settle on the skin and then enter the blood stream. High speed cutting will create fumes that can make breathing hazardous.
Cutting fluids will degrade over time because of the contaminants that filter into the oil. Unwanted oil or sump oil is intermixed with the cutting fluid from various sources. Safe disposal of cutting oil is regulated by the EPA, which sets up specific instructions. The disposal is the same as automobile oil with minimal impact to the environment. Modern disposal techniques involve ultrafiltration. This process runs the fluids through membranes, such as ceramic, to trap the contaminants. Many machinists have engineered solutions for overall collecting, separating and recycling. Over decades the enhancements to cutting fluids and their disposal has made industrial machining safer and more productive.