When the rotating speed and feed rate are constant, the cutting length of each sample cut by gray cast iron remains unchanged at 1000 mm. The cutting resistance of gray cast iron in Z, X and Y directions not at the same cutting depth of gray cast iron is shown in Figures 1, 2 and 3.

It can be seen from the figure that the cutting force of the two groups of samples increases with the increase of cutting depth. Under the three cutting depths, the main cutting force (Fig. 1), feed resistance (Fig. 2) and cutting depth resistance (Fig. 3) of sample 1 are lower than those of sample 4. When the cutting depth is 1 mm, 1.25 mm and 1.5 mm, the main cutting force FZ of sample 1 is 3.7%, 7.7% and 4.2% lower than that of sample 4, respectively. It can be concluded that the cutting resistance of the blade when cutting sample 1 is small, and the cutting resistance when cutting sample 4 is large.

The cutting resistance of the sample in the cutting process can reflect whether the material itself is easy to be cut to a certain extent. The smaller the cutting resistance is, the easier the sample is to be cut, and the better the machining performance is. Therefore, the machinability of sample 1 is better than that of sample 4.