Which types of end mills can plunge cut a hole?

The ability to plunge cut a hole is determined by the design of the end mill. Center cutting end mills are specifically designed with cutting edges that extend to the center of the tool, allowing them to effectively plunge into the material and create holes.

In this context, the two-fluted and four-fluted center cutting end mills are capable of making plunge cuts because their geometry includes sharp cutting edges at the tip, which enables them to cut directly down into the material.

Two-fluted end mills typically have a larger chip removal capability and are favored for plunge cutting due to their optimal flute design, allowing for better chip clearance during the cutting process. Four-fluted end mills, while they may have more cutting edges, also include center cutting capabilities if designed as such and can still perform plunge cuts, albeit with potential limitations in chip clearance compared to two-fluted variants.

Other types of end mills, such as three-fluted or other non-center cutting designs, may not be able to plunge cut effectively because the center does not have cutting edges, which is crucial for starting a cut directly down into a material. Hence, the correct answer includes both types of end mills that are specifically designed for this cutting action.