In CNC machining, if it is normal dry cutting, it is reasonable that almost all steel chips appear purple. Today we will talk about the color change of iron chips in CNC processing.

With the increase of cutting temperature, the change rule of iron chip color in dry cutting is as follows: silver white → light yellow → dark yellow → magenta → dark blue → blue → blue gray → gray white → purple black. The temperature changes from about 200 ℃ to more than 500 ℃.

The process of iron chip color change is the process that most of the work consumed in the cutting process is converted into cutting heat. At the same time, it can also be regarded as the process of tool loss (sharp passivation severe passivation scrap) (when there is no chip buildup). Note that the cutting temperature we usually call is the average temperature.

The relationship between chip color and cutting temperature is as follows

Silver White: < 200 ℃

Light yellow: ≈ 220 ℃

Dark blue: ≈ 300 ℃

Light gray: ≈ 400 ℃

Dark purple black: > 500 ℃

When the cutting color is blue or blue purple, it is more reasonable. If it is silver or yellow, it does not give full play to the efficiency. If it is blue gray, the cutting amount is too large. If high speed steel tool is used, it is better to cut silver and yellowish. If cutting blue, it is necessary to reduce the speed or feed.

Of course, it's only one of the methods to determine reasonable parameters by color change. Have you got it?