During CNC machining, a nozzle near the cutting area sprays an oily liquid called cutting fluid.
This cutting fluid is a lubricant used for lubrication, cooling, and cleaning in CNC machine tools. Therefore, cutting fluid is crucial in automated CNC machining.
Let’s now explore cutting fluids, their types, and applications. This article will also discuss techniques for selecting the right cutting fluid for manufacturing.
What is Cutting Fluid?
Cutting fluid is an industrial liquid used in metal cutting operations such as CNC machining to lubricate and cool the cutting tool and the metal being cut. Other names for this liquid include cutting oil, coolant, lubricant, and cutting paste.
Cutting fluids are typically manufactured using petroleum fractions, animal fats, vegetable oils, water, air, or other basic ingredients. It consists of several very useful components that are scientifically combined to work effectively together.
Reducing fluids have a much superior cooling capacity than saponified oils because they do not have the disadvantages of traditional soap-based emulsions, such as a tendency to develop an unpleasant odor in warmer months and difficulty in diluting in colder months.
It is harmless, has no unpleasant odor, poses no harm to people or machines, does not cause air pollution, and will not damage the paint on lathes. Furthermore, it can be used for grinding and cutting ferrous steel.
Characteristics of a High-Quality Cutting Fluid:
The following lists some characteristics that a suitable cutting fluid should possess: Thermal conductivity is a method of measuring the ability of an object to transfer heat. Therefore, it is important to assess how well the cutting fluid removes heat from the workpiece and tool.
The more heat a cutting fluid absorbs before it becomes too hot or boils, the higher its heat capacity.
Cutting fluid has low viscosity, making it easy to move. It also prevents the formation of viscous substances when chips mix with the fluid.
This type of cutting fluid should not damage the tool or the object you are cutting.
High-quality cutting fluid is not only not acidic, but it also prevents parts from rusting and oxidizing.
Because it may come into contact with people and the environment, high-quality cutting fluid will not cause harm.
Cutting fluid does not cause a chemical reaction when it comes into contact with surfaces. This would not only damage the surface but also make the fluid worse.
A practical cutting fluid should not leave any odor on the machine or the parts used to make the machine.
High-quality cutting fluid should be clear enough that the object being cut can still be seen.
This type of cutting fluid should not decompose quickly during use or storage.
The role of cutting fluid in CNC machining:
Lubrication: Cutting fluid leaves an oil film on the workpiece and tool surfaces. This film can even penetrate the smallest metal gaps and irregular areas, which helps reduce the amount of friction between metals. The following effects can be achieved:
It reduces tool wear and extends its service life.
Cutting fluid can also reduce cutting resistance and power consumption during machining.
Burnt edges should be avoided, improving the precision of machined surfaces.
Cooling: Cutting fluids can reach temperatures of 600-1000 degrees Celsius, reducing the heat generated during cutting.
Heat dissipation is not easy, causing the workpiece to heat up. This is especially true for workpieces made of materials with low thermal conductivity, such as stainless steel.
Using cutting fluid as a means of reducing temperature can have the following effects:
The amount of thermal deformation experienced by the tool is minimized, and its service life is extended.
To maintain machining accuracy, thermal deformation of the workpiece and tool must be prevented.
High-speed machining is possible.
Cleaning: Chips generated during cutting can be flushed away, and spraying cutting fluid onto the workpiece cleans it. This can have the following effects:
It prevents chip adhesion and scratching of the workpiece by taking preventative measures.
Cutting fluid can also prevent defects caused by chip buildup and clogging during machining.
Preventing chip entanglement and tool damage by taking preventative measures. How many types of cutting fluids are used in CNC machining?
As mentioned earlier, chip removal, corrosion protection, cooling, and lubrication are some of the basic functions of cutting fluids.
The requirements for cutting fluids will vary depending on the type of manufacturing operation you are performing; therefore, you should choose a cutting fluid based on these varying requirements.
Emulsions: Emulsions are soluble oils that can be produced by mixing water and mineral oil in a specific ratio (10% to 20% oil to water). They can also be found in nature.
Additives are also included, such as sodium sulfonate, which helps the oil and water mix more effectively; corrosion inhibitors to improve the product’s corrosion resistance; bactericides to inhibit bacterial growth; and anti-wear additives to enhance lubrication.
This type of cutting fluid is used when rapid cooling is required, such as in high-speed drilling, milling, turning, and grinding processes.
Emulsions are superior to synthetic cutting fluids in terms of lubrication and corrosion protection.
Pure Oils: Natural, pure oils can come from plants or animals. Therefore, cutting fluids made using them are considered environmentally friendly.
They possess excellent lubricating properties and are virtually water-free or even anhydrous, making their rust-preventing capabilities even more impressive.
However, they are significantly more expensive than other cutting fluids because they are organic.
Therefore, pure oils are not used for heavy cutting and drilling activities unless added as additives to other cutting fluids to enhance lubrication.
Liquids made from synthetic components: Organic and inorganic chemical components are mixed with water to produce synthetic liquids. Some of these additives enhance lubrication, reduce rust and corrosion, and improve overall performance.
The addition of synthetic liquids can effectively promote cooling of the working area and efficient chip removal.
Semi-synthetic liquids are commonly used as cutting fluid. They are combinations of water-based, synthetic, and emulsion-based liquids. Therefore, they possess the qualities common to both emulsion and synthetic liquids.
