PCBN for Cutting Tools with Wide Range of Hardness - From Cast Iron, Sintered Alloys to Hardened Steel

Driven by the need for labor savings and higher productivity, the demand for automation of cutting processes has been increasing. In automated operations, machines are often required to run continuously for long periods, and in many cases, the machining process involves mixed workpieces with different hardness levels. In recent years—especially in the automotive sector—there has also been a growing use of composite materials that combine resin with sintered alloys or other materials with significantly different hardness and properties.

Cutting tools are typically selected to match the workpiece being machined. For cBN tools, which are widely used for hard to cut materials, high content grades (with cBN concentrations of 90 vol% or more) are commonly used for cast iron and sintered alloys, while mid content grades (80 vol% or less) are used for hardened steels. As a result, machining processes that involve mixed workpieces often require tool changes, posing a major challenge for automation. Additionally, there is a rising need for tools capable of handling composite materials.

To address these challenges, Resonac proposes , a PCBN material for cutting edges that offers an excellent balance of wear resistance and fracture resistance, enabling stable machining from cast iron to hardened steel—all with a single tool (Fig.1).

Although KT75X contains 75 vol% cBN, its optimal combination of different grain sizes achieves a highly dense packing structure (Fig. 2). This design delivers both excellent cutting performance and extended tool life.

When KT75X is used as the cutting edge material, a single grade can cover a wide application range, from cast iron and sintered alloys to hardened steels. Since there is little need to change tools according to the workpiece, enables machining from roughing to finishing in one setup, making it highly suitable for automated machining processes.

With thermal conductivity over 30% higher than our conventional grades, KT75X provides significantly improved heat dissipation directly at the cutting edge. This enhanced thermal management helps suppress edge fracture caused by heat generation during machining.

KT75X provides lower electrical resistivity and superior conductivity compared with competitor materials, enabling processing by wire EDM.