Look At The Color Of The Iron Shavings To Judge The Processing Status

In CNC machining, if it is normal dry cutting, it is reasonable for almost all the chips cut out of steel to appear purple. Today, let's talk about the changes in the color of iron shavings in CNC machining.

With the increase of cutting temperature, the color of iron shavings during dry cutting changes as follows: silver-white→ light yellow → dark yellow → magenta→ dark blue → blue → blue-gray → off-white → purple-black. The temperature change can rise from about 200℃ to more than 500℃.

The process of changing the color of iron shavings is the process by which most of the work consumed during the cutting process is converted into cutting heat. At the same time, it can also be regarded as the process of tool loss (sharpness－passivation－severe passivation－scrap) (when there is no chip accumulation). Note that what we usually call the cutting temperature refers to the average temperature.

The relationship between chip color and cutting temperature：

Silver white: below <200℃

Light yellow: ≈220℃

Dark blue: ≈300℃

Light gray: ≈400℃

Dark purple black: >500℃

It is more reasonable when the cutting color is blue or blue-purple. If it is silver-white or yellow, the efficiency is not fully utilized, and if it is blue-gray, the amount of cutting is too large. If high-speed steel tools are used, it is appropriate to cut to silver-white and yellowish, and if it is cut to blue, the speed or feed should be reduced.

Of course, relying on color changes to determine reasonable parameters is only one of the methods or means. Have you got it?