With the increase of cutting temperature, the color of iron filings during dry cutting changes as follows: silver white→light yellow→dark yellow→magenta→dark blue→blue→blue-gray→gray white→purple black. The temperature change can rise from about 200°C to over 500°C.
The process of iron filings color change is the process in which most of the work consumed in the cutting process is converted into cutting heat, and it can also be regarded as the process of tool wear (sharpness-passivation-severe passivation-scrap) (no product In the case of chipping) Note that what we usually call the cutting temperature refers to the average temperature.
The relationship between chip color and cutting temperature:
Silver white: <200℃ below
Light yellow: ≈220℃
Dark blue: ≈300℃
Light gray: ≈400℃
Deep purple black: >500℃
It is more reasonable when the cutting color is blue or blue-violet. If it is silvery white or yellow, the efficiency is not fully exerted. If the cutting color is blue and gray, the cutting amount is too large. Use high-speed steel cutting tools, it is advisable to cut to silver and yellowish, if cut blue, reduce the speed or feed.
Of course, determining reasonable parameters by color changes is only one of the methods or means. Have you got it yet?