Machining Centers and Milling Machines

The term “machining center” describes almost any CNC milling and drilling machine that includes an automatic toolchanger and a table that clamps the workpiece in place. On a machining center, the tool rotates, but the work does not. Vertical machining centers (VMCs) generally favor precision while horizontal machining centers (HMCs) generally favor production — but these are loose generalizations, and plenty of machining centers break out of them. Five-axis machining centers are also common, which can pivot the tool and/or the part in order to mill and drill at various orientations. In some cases, these machines only position parts in five axes (commonly referred to as 4+1 or 3+2 machining). In others, full five-axis machining is used to create contoured features. Machining centers are also used as a secondary operation machine to complete parts that were partially machined on a lathe.