The coolant for CNC machine tools, also known as cutting fluid or coolant, is an indispensable auxiliary material in the metal processing process. The following is a detailed analysis from three aspects: composition, function and application scenarios:
1. The core components of coolant
The composition of coolant varies according to the type, and is mainly divided into three categories:
Pure oil coolant
Base oil: mineral oil, vegetable oil (such as rapeseed oil) or animal oil, providing lubrication and rust prevention.
Additives: extreme pressure additives such as sulfur, phosphorus, and chlorine to enhance lubricity and reduce tool wear.
Soluble oil (emulsion)
Oil: more than 40% (such as mineral oil), mixed with water to form an emulsion.
Emulsifier: Stable mixing of oil and water, with both cooling and lubrication functions.
Rust inhibitor: such as nitrates and molybdates, to prevent rust on machine tools and workpieces.
Bactericide: Control the growth of bacteria and mold to extend the life of coolant.
Synthetic coolant
Chemical additives: such as water-soluble polyether and silicone defoamer, which are completely based on chemical synthesis and have no oil.
Extreme pressure agent: Improve lubricity during high-speed cutting.
Preservatives: such as triethanolamine, to prevent metal corrosion.
2. Core functions of coolant
Cooling effect
Reduce the temperature of tools, workpieces and machine tools to prevent thermal deformation (such as the workpiece's precision decreases due to high temperature expansion).
Reduce cutting heat to prevent the tool from softening or aggravating wear due to overheating.
Lubricating effect
Form a lubricating film between the tool and the workpiece to reduce friction and extend tool life (experiments show that the use of coolant can increase tool life by 30%-50%).
Improve the quality of the machined surface and reduce roughness.
Cleaning effect
Flush the chips to prevent chips from accumulating and scratching the workpiece surface or clogging the tool.
Keep the processing area clean and improve processing efficiency.
Anti-rust effect
Prevent machine tool guides and workpiece surfaces from rusting due to moisture.
3. Typical application scenarios
General processing
Applicable to conventional operations such as turning, milling, and drilling, such as automotive parts processing.
Synthetic fluids are often used for high-speed grinding due to their strong cooling performance; soluble oils are mostly used for heavy-duty processing due to their good lubricity.
High-pressure cooling system
Deep hole processing: Coolant is directly sprayed to the tip of the tool to discharge chips (such as barrel drilling).
High-speed cutting: The pressure can reach 70-100 bar to improve processing efficiency (such as aerospace aluminum alloy parts processing).
Special material processing
Difficult-to-process materials: such as titanium alloys and high-temperature alloys, special coolants are required to prevent tool adhesion.
Precision processing: such as mold manufacturing, low-foam, high-cleanliness coolants are required to ensure surface finish.
4. Precautions for use
Regular replacement: The performance of the coolant decreases after deterioration, and it needs to be replaced every 3-6 months.
Concentration control: Too high a concentration is prone to foaming, and too low a concentration is insufficient cooling, and a refractometer is required for monitoring.
Safety and environmental protection: Avoid using coolants containing carcinogens such as nitrites, and waste liquids must be handled professionally.
Summary: CNC machine tool coolants significantly improve processing efficiency, tool life and workpiece quality through four major functions: cooling, lubrication, cleaning and rust prevention. When choosing, it is necessary to comprehensively consider the processing type, material characteristics and environmental protection requirements, and strictly follow the operating specifications to ensure safety and efficiency.