Cubic boron nitride tools can process quenched steel, mold steel, tool steel, alloy steel, gray iron, white iron, etc. with a hardness above HRC60. High-hardness cast iron castings are difficult to process materials.
Generally, it is enough to use carbide. As for the feed, it depends on the amount of cutting done on your back. If your back cutting amount is 3-5 mm, 0.5 is generally used. -1.2 is fine. If it is 5-8 mm, generally 0.4-1.0 is fine. Of course, it depends on the size of your workpiece. The tool can be made of high-speed steel or carbide. If you don't have a grinder, it's best to leave 0.03 to 4 millimeters and sand it with emery cloth.
To increase tool wear, just choose sharp tools. For CNC, it is best to use a special stainless steel turning machine to clamp the tool. High-speed steel tools and carbide tools can be used. Mainly pay attention to the chip breaker and tool angle. In order to suppress the generation of built-up edges and burrs and improve surface quality, the cutting amount when machining with carbide tools is slightly lower than that for turning general carbon steel workpieces. In particular, the cutting speed should not be too high. Generally, the recommended feed speed is 60m per minute - 80m, 0.15mm-0.6mm per revolution, cutting amount 4mm-7mm, speed 700-1000.