CNMG

CNMG is a standard designation used in the cutting tools industry to describe a type of indexable turning insert. The CNMG family is defined by a rhombic (diamond-shaped) insert that sits in a corresponding tool holder and typically features multiple cutting edges, allowing for edge reindexing to extend usable life. The four-letter code communicates the insert’s general geometry and seating configuration, as defined by ISO conventions, with exact edge geometry, tolerance, and coating varying by manufacturer.

Manufactured primarily from carbide, CNMG inserts are produced in a range of coatings and substate options to suit different materials and cutting conditions. Common coatings include TiN, TiCN, TiAlN, and Al2O3, which are applied to improve hardness, wear resistance, and heat tolerance. These inserts are used in external turning, facing, and boring operations on CNC lathes and turning centers. They are employed across different workpiece materials, including steel, stainless steel, cast iron, and nonferrous metals, with grade selection guided by cutting speed, feed, material hardness, and desired surface finish.

Sizes and edge specifics are specified by additional SKU data provided by manufacturers, often including the inscribed circle size, thickness, corner radius, and tolerance. Different CNMG variants may exist that vary in size or corner radius, so users consult product catalogs to select the appropriate insert for a given application. Overall, CNMG inserts are a widely used option in metalworking for their combination of multiple usable edges and versatility across turning operations.