What Substrate Should Be Used For Machining For Hardened Steels?
When milling Hardened Steels HRc 50-70, it is not possible to use a standard Micrograin Carbide substrate. Not only is the workpiece very hard, but to reduce heat fluctuations on the cutting tool, dry machining is typically used. For this, tools are required that contain superior grades of carbide like Ultrafine Micrograin Carbide (such as YG-1 X-Power) or Nanograin Carbide (such as YG-1 X5070).
These carbide grades are much denser and therefore harder wearing with extremely high heat resistance, making them perfect for machining hardened steels. In comparison, a tough/general grade of carbide or HSS will wear fast due to the extreme heat generated.
What Sort of Coating is Required For Hardened Steels?
The coating of a tool can have a dramatic effect on its performance. A standard TiAlN or TiCN coating may only have heat resistance up to 800°C, which will wear down quickly when machining Hardened Steels.
YG-1 has developed a special Y1200 blue coating found on X5070 milling cutters specifically for this problem. This coating has a very high heat resistance of 1200°C! Combining this coating with nanograin carbide means our X5070 cutters can machine high hardened steels up to 70 HRc at ultra-high speeds and feeds with incredible tool life!
For setups involving older machine tools, machines with lower spindle speeds or suffering from spindle wear or vibration, the X5070 could be too hard and tool life can be unreliable. In these circumstances, an Ultrafine Micrograin Carbide tool would be more suitable (such as YG-1’s X-Power cutter). It is more forgiving and can be run at slower cutting speeds due to the toughness of the carbide substrate.