Function and Benefits of Cutting Fluid
– Cutting fluid is a coolant and lubricant designed for metalworking processes.
– Different types of cutting fluids exist, including oils, emulsions, pastes, gels, aerosols, and gases.
– Cutting fluids can be made from various raw ingredients such as petroleum distillates, animal fats, plant oils, water, etc.
– Most metalworking processes can benefit from cutting fluid, except for cast iron and brass.
– The properties of a good cutting fluid include temperature control, tip lubrication, safety, and rust prevention.
– Cutting fluids help remove heat, reduce friction, prevent thermal expansion, and chemical reactions.
– They lubricate the interface between the tool’s cutting edge and the chip, preventing friction, heat generation, and chip welding onto the tool.
– Cutting fluids may reduce cutting forces and tool wear through the Rehbinder effect.
– Various methods can be used to apply cutting fluid, such as flooding, spraying, dripping, misting, and brushing.
– High-pressure pumping is commonly used in manufacturing, but smaller machine tools may not require it.
– New delivery methods include minimum quantity lubrication and cryogenic cooling.
– Through-tool coolant systems deliver coolant directly to the cutting interface.
Types of Cutting Fluids
– There are three types of cutting fluid liquids: mineral, semi-synthetic, and synthetic.
– Semi-synthetic coolants combine oil and water and have properties like rust inhibition and pH stability.
– Mineral oils have been used since the late 19th century and vary in viscosity.
– Synthetic coolants are water-based and originated in the late 1950s.
– Oil concentration in cutting fluids can be measured using techniques like manual titration and refractometry.
– Specific cutting fluids are effective for different metals, such as kerosene and rubbing alcohol for aluminum, WD-40 and 3-In-One Oil for various metals, way oil for both cutting and lubrication, and dielectric fluid for electrical discharge machines (EDMs).
Different Forms of Cutting Fluid
– Cutting fluid can take the form of a paste or gel for hand operations, commonly used in sawing metal with a bandsaw.
– Aerosol (mist) cutting fluids have traditionally had drawbacks, but minimum quantity of lubricant (MQL) aerosol delivery provides precise and targeted lubrication for dry machining.
– Carbon dioxide (CO2) can be used as a coolant, expanding and cooling the cutting tool and workpiece, while solid CO2 crystals are redirected into the cut zone for temperature control.
– Compressed air and liquid nitrogen can also be used as coolants.
Safety Concerns and Components of Cutting Fluid
– Occupational exposure to cutting fluids is associated with cardiovascular disease, illness, and injury.
– Mechanisms of illness or injury include skin contact, splattering, and mist inhalation.
– Chemical toxicity and physical irritation are safety concerns.
– Certain additives, such as lead and 1,1,1-trichloroethane, have been phased out due to toxicity.
– Cutting fluid components include the fluid itself, metal particles, bacterial or fungal populations, biocides, and corrosion inhibitors.
Degradation, Replacement, Disposal, and Coolant Management
– Tramp oil formation from lubrication oil seeping into coolant can be managed using skimmers.
– CNC additives can improve tramp oil management.
– Disposal of degraded cutting fluid must consider environmental impact, and techniques like ultrafiltration concentrate the oil phase for disposal.
– Engineered solutions exist for chip handling and coolant management, including collecting, separating, recycling chips and coolant, grading chips by size and type, separating tramp metals, and centrifuging coolant off chips. Source: https://en.wikipedia.org/wiki/Cutting_fluid
Cutting fluid is a type of coolant and lubricant designed specifically for metalworking processes, such as machining and stamping. There are various kinds of cutting fluids, which include oils, oil-water emulsions, pastes, gels, aerosols (mists), and air or other gases. Cutting fluids are made from petroleum distillates, animal fats, plant oils, water and air, or other raw ingredients. Depending on context and on which type of cutting fluid is being considered, it may be referred to as cutting fluid, cutting oil, cutting compound, coolant, or lubricant.
Most metalworking and machining processes can benefit from the use of cutting fluid, depending on workpiece material. Common exceptions to this are cast iron and brass, which may be machined dry (though this is not true of all brasses, and any machining of brass will likely benefit from the presence of a cutting fluid).
The properties that are sought after in a good cutting fluid are the ability to:
- Keep the workpiece at a stable temperature (critical when working to close tolerances). Very warm is acceptable, but extremely hot or alternating hot-and-cold are avoided.
- Maximize the life of the cutting tip by lubricating the working edge and reducing tip welding.
- Ensure safety for the people handling it (toxicity, bacteria, fungi) and for the environment upon disposal.
- Prevent rust on machine parts and cutters.
