The gash on an end mill refers to the recessed area at the tip of the tool, which is ground into the flute to create a cutting edge that allows for efficient chip evacuation and proper cutting action. It plays a critical role in the center-cutting capability of an end mill, as it helps form the primary cutting edges at the end face of the tool.
The design of the gash influences how effectively the end mill plunges into material, making it particularly important for tools used in operations like ramping, drilling, or slotting. A well-designed gash provides sharp cutting edges, reduces cutting forces, and facilitates smooth material removal. The depth, width, and geometry of the gash vary depending on the specific end mill type, flute configuration, and intended application.