In which operation is an end mill typically engaged with the workpiece on its bottom and sides?

The operation where an end mill is typically engaged with the workpiece on its bottom and sides is slot milling. During slot milling, the end mill cuts into the material to create a slot or groove, leveraging both its bottom and side cutting capabilities. This dual engagement allows the end mill to effectively remove material, achieving the desired width and depth of the slot.

In contrast, tapering primarily focuses on producing a tapered surface, which does not fully utilize the sides of the end mill as the cutting is mainly along the bottom. Turning involves a rotating workpiece and uses a single-point cutting tool, not an end mill. Drilling involves the use of a drill bit which primarily cuts from the bottom, rather than along the sides, as is characteristic of slot milling. Therefore, slot milling is fundamentally defined by the end mill's ability to engage with the workpiece material on both its bottom and sides simultaneously, making it the correct operation in this context.