Types, Functions and Additives of Cutting Fluids
December 10, 2022
Function of cutting fluid 1) Lubrication: The cutting fluid can penetrate into the tool, chip and machining surface to form a thin layer of lubricating film or chemical adsorption film. Therefore, the friction between them can be reduced. Its lubricating effect mainly depends on the penetration ability of cutting fluid, the ability of adsorption and film formation, and the strength of lubricating film. The lubricating ability of cutting fluid can be changed by adding additives with different compositions and proportions. The lubricating effect of cutting fluid is also related to cutting conditions. For example, the higher the cutting speed, the greater the cutting thickness, and the higher the strength of the workpiece material, the worse the lubrication effect of the cutting fluid. 2) Cooling effect: Cutting fluid can take away a large amount of cutting heat from the cutting area, reducing the cutting temperature. The cooling performance of cutting fluid depends on its heat transfer coefficient, specific heat capacity, gasification heat, gasification speed, flow rate, flow rate and temperature. Generally speaking, the cooling performance of aqueous solution is the best, followed by emulsion, and oil is the worst. 3) Cleaning function: The flow of cutting fluid can wash away the fine chips and falling abrasive particles on the cutting area and the machine tool guide rail, which is very important for grinding, deep hole machining and automatic line machining. The cleaning ability of cutting fluid is related to its protective film or its combination with metal to form a passive film, which has good permeability, fluidity and service pressure for workpieces, machine tools and tools, and is also affected by the performance of surfactants 4) Anti-rust effect: After adding antirust additive to cutting fluid, it can form strong adhesion antirust and anti-corrosion effect on metal material surface.
Additives in cutting fluid Additives are some chemical substances, which can be divided into oily additives, extreme pressure additives, surface active additives and other additives. 1) Oily additives: Oily additives contain polar molecules, which can form a firm adsorption film with the metal surface, and can play a better role in lubrication at a lower cutting speed. Oily additives include animal oil, vegetable oil, fatty acid, amine, alcohol, lipid, etc. 2) Extreme pressure additives: Extreme pressure additives are organic compounds containing sulfur, phosphorus, chlorine, iodine, etc. They react chemically with metal surfaces at high temperatures to form a chemical lubricating film that can withstand higher temperatures and pressures. The lubricating film can withstand high pressure, prevent metal interface from direct contact, reduce friction coefficient and maintain good cutting lubrication conditions. 3) Surfactant: Surfactant, namely emulsifier, has the function of emulsification and lubrication of oily additives. The former makes mineral oil and water mixed and emulsified to form emulsion; The latter is adsorbed on the metal surface to form a lubricating film. The commonly used surfactants are sodium petroleum sulfonate, sodium oleate soap, etc. They have good emulsifying properties, and have certain cleaning, lubricating, and antirust properties. In addition, there are anti rust additives (such as sodium nitrite, sodium petroleum sulfonate, etc.), Anti Foam additives (such as dimethyl silicone oil) and anti mold additives (such as phenol, etc.). The cutting agent with good effect can be obtained if the additives are properly selected.
Type of cutting fluid There are mainly two kinds of cutting fluids, water based and oil based. The former has strong cooling capacity, while the latter has outstanding lubricating performance. The main components of water-based cutting fluid are water, chemically synthesized water or emulsion. The water-based cutting fluid is added with antirust agent or extreme pressure additive. The main components of oil-based cutting fluid are various mineral oils, animal oils, vegetable oils, or composite oils composed of them, and various additives, such as extreme pressure additives and oil-based additives, can be added as required.
