Why do cutting tools need to be “passivated”?

Tool “passivation” is a process of micro – treating the cutting edge of a tool. The purpose is to improve the performance of the tool by removing tiny burrs and irregularities on the cutting edge, or by moderately rounding the sharp cutting edge. This treatment doesn’t actually make the tool blunt; instead, it makes the cutting edge more durable and stable, thus enhancing the cutting effect.

A.The main reasons for tool “passivation”

1. Improve tool strength and wear resistance: A sharp cutting edge is prone to developing tiny cracks or chipping during use. Through passivation treatment, these irregular micro – edges can be eliminated, enhancing the overall strength of the tool and reducing the risk of the cutting edge cracking.
2. Reduce tool wear: The passivated cutting edge is more rounded, which can reduce the wear caused by stress concentration during the cutting process, thus extending the tool’s service life.
3. Improve the surface quality of the workpiece: The tool after passivation treatment can reduce the surface roughness of the workpiece and improve its surface finish. This is particularly important for high – precision machining.
4. Decrease cutting resistance: After the cutting edge is passivated, the friction during cutting is reduced, and the stability of the tool during the cutting process is enhanced, which helps improve the machining efficiency.
5. .Improve machining consistency: The tool after passivation treatment performs more stably in different machining processes, contributing to achieving consistent machining results

B.The purposes of tool “passivation”

Edge passivation technology aims to address the defect of microscopic notches on the tool edge after grinding. It reduces or even eliminates these sharp peaks, thereby making the edge smooth and flat, achieving the goal of making the edge both sharp, strong, and durable.

C.The main effects of tool “passivation”

1.Edge rounding:

Burrs on the edge cause tool wear, and the surface of the machined workpiece also tends to become rough. However, after passivation treatment, the edge becomes extremely smooth, greatly reducing the occurrence of edge chipping, and the surface finish of the workpiece is also improved. The polishing treatment of the chip – removal groove is to uniformly polish the tool groove, which can improve its surface quality and chip – removal performance.

2.Polishing treatment of the chip – removal groove:

The smoother and flatter the groove surface is, the better the chip – removal effect will be, enabling higher – speed cutting. At the same time, with the improvement of surface quality, the risk of the tool galling with the processed material is also reduced. Moreover, it can reduce the cutting force by 40%, making the cutting process more smooth.

3.Polishing of the coating

After coating, some tiny protruding droplets will appear on the surface of the tool. This increases the surface roughness, causing the tool to generate relatively large frictional heat during the cutting process, thus reducing the cutting speed. After passivation and polishing, these droplets are removed. At the same time, many small pores are left. During processing, these pores can absorb more cutting fluid, significantly reducing the heat generated during cutting and greatly increasing the cutting speed.

Therefore, tool passivation is an effective means to improve tool performance and is widely used in various precision machining fields.