"Why can metal cutting fluids reduce tool wear?"

During metal cutting processes, the intense interaction between the cutting tool, the workpiece, and the chips leads to tool wear, which negatively impacts machining accuracy and production efficiency. As a crucial machining auxiliary medium, metal cutting fluid helps minimize tool wear and extend tool life through multiple synergistic effects. Its working mechanisms primarily revolve around cooling, lubrication, chip removal, and rust prevention. These functions work together to provide comprehensive protection for the cutting tool.
 

1. Cooling Effect: Reducing Temperature in the Cutting Zone
In metal cutting, significant heat is generated by the plastic deformation of the metal being cut and the friction between the tool, workpiece, and chips. This causes a sharp rise in temperature within the cutting zone. High temperatures can reduce the hardness and strength of the tool material, accelerating thermal wear and thermal fatigue. Metal cutting fluids rapidly dissipate heat from the cutting zone through convection, conduction, and vaporization, effectively lowering the cutting temperature. When the fluid continuously acts on the tool's cutting edge and the workpiece contact area, it promptly prevents temperature spikes, avoiding wear phenomena such as tool softening and edge chipping caused by overheating. Meanwhile, a stable thermal environment helps maintain the mechanical properties of the tool material, ensuring it retains its cutting capabilities throughout the process and reducing wear triggered by temperature fluctuations.

2. Lubrication Effect: Mitigating Interfacial Friction
Friction between the tool, workpiece, and chips is a major cause of tool wear, encompassing various forms such as adhesive and sliding friction. Metal cutting fluids possess excellent lubricating properties; their molecules form a uniform lubricating film on the surfaces of the tool, workpiece, and chips. This film effectively isolates direct contact between the tool and the workpiece, reducing the coefficient of friction at the interface. During cutting, the lubricating film decreases the adhesion between the tool's rake face and the chips, minimizing the formation of built-up edges (BUE)—the formation and shedding of which can cause impact and wear on the tool's cutting edge. It also reduces sliding friction between the tool's flank face and the machined surface, slowing down flank wear. By improving the friction conditions at the cutting interface, the cutting fluid significantly reduces abrasive and adhesive wear, extending the tool's effective service time.

3. Chip Removal Effect: Preventing Chips from Scratching the Tool
If the chips generated during cutting are not removed promptly, they will accumulate in the cutting zone, causing secondary friction and extrusion against the tool and workpiece, leading to additional tool wear. Metal cutting fluids have sufficient fluidity and pressure to quickly flush away chips from the cutting zone, preventing them from lingering around the tool. High-speed flowing fluid carries the chips away from the cutting edge and chip flutes, preventing scraping against the tool's edge and reducing scratches and wear on the tool surface. Additionally, during chip removal, the fluid cools the chips, preventing thermal damage caused by prolonged contact with high-temperature chips. Timely and efficient chip removal not only reduces tool wear but also improves the machining environment and enhances process stability.

4. Rust Prevention Effect: Protecting the Tool Surface Condition
After metal cutting, residual cutting fluid, debris, and impurities often remain on the surfaces of the tool and workpiece. If not treated in time, these can cause rust in humid environments. Rust on the tool surface destroys its original surface precision and integrity, making it more susceptible to wear during subsequent use. Metal cutting fluids typically contain rust-preventative additives that form a dense protective film on the tool surface. This film isolates the tool from corrosive media in the air, such as oxygen and moisture, preventing rust. Even during machining pauses or after the process is complete, this protective film continues to function, keeping the tool surface clean and intact. Preventing rust not only extends the storage life of the tool but also ensures it is in optimal cutting condition for every use, eliminating wear hazards caused by corrosion.
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