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The reasones to passivate the CNC cutting tools

Nov. 10, 2023

Why do we need to passivate the CNC cutting tools used in machining centers? In fact, passivating the tools does not mean what people literally understand, but rather a way to improve their lifespan.

The quality of the tools is improved through processes such as leveling, polishing, and deburring. This is actually a normal procedure for the tools after precision grinding but before coating.

What is tool passivation?

Tool passivation involves deburring, leveling, and polishing the tools to improve their quality and prolong their lifespan. It is a process that takes place after precision grinding and before coating. Currently, there is no unified name for this process internationally, and it can be referred to as "edge passivation," "edge strengthening," "edge honing," "edge preparation," or "edge radiusing" (ER) treatment.

Why do we need to passivate the tools?

After ordinary grinding with abrasive wheels or diamond wheels, there are microscopic notches (micro burrs and saw kerfs) of different degrees on the cutting edge of the tools. During the cutting process, these microscopic notches are prone to expansion, accelerating tool wear and damage.

Modern high-speed machining and automated machine tools demand higher performance and stability from the tools, especially for coated tools which must undergo edge passivation before coating to ensure the durability and lifespan of the coating.

The purpose of tool passivation

The purpose of edge passivation technology is to address the defects caused by microscopic notches on the cutting edge of the tools after grinding, reducing or eliminating their sharpness and achieving a smooth and even surface. This ensures that the tools are both sharp and durable.

The main effects of tool passivation

Rounding of the cutting edge: Removing burrs and achieving precise and consistent edge rounding.

The reasones to passivate the CNC cutting tools

Burrs on the cutting edge result in tool wear and roughening of the workpiece surface. After passivation treatment, the cutting edge becomes smooth, greatly reducing micro burrs and improving the surface finish of the workpiece.

Polishing treatment for chip evacuation channels

Uniform polishing of the tool grooves improves surface quality and chip evacuation performance.

The reasones to passivate the CNC cutting tools

The reasones to passivate the CNC cutting tools

The smoother and more polished the surface of the groove, the better the chip evacuation, enabling higher cutting speeds. At the same time, with improved surface quality, the risk of the tool jamming with the workpiece material is reduced. Additionally, it can reduce cutting force by 40%, resulting in smoother cutting.

Polishing of the coating

Removing the protruding droplets that occur after coating the tools, improving surface finish, and increasing the absorption of lubricating oil.

The reasones to passivate the CNC cutting tools

The reasones to passivate the CNC cutting tools

Coated tools can develop small protruding droplets on the surface, increasing surface roughness and leading to significant frictional heat during cutting, which reduces cutting speed. After passivation and polishing, these droplets are removed, leaving behind many small holes that can absorb more cutting fluid during machining. This greatly reduces the heat generated during cutting and significantly improves cutting speed.