A machining center comprises a bed and an arch-shaped column having a pair of post portions spaced from each other in the transverse direction of the bed and a crossbeam portion connecting the post portions. A spindle head is supported on the crossbeam portion of the column to be movable both in the vertical direction and in the transverse direction of the bed and supports a spindle which is rotatable about a substantially vertical rotating shaft and on which a tool is demountably mounted. A base table is supported on the bed between the post portions of the column to be movable back and forth and a support supported on the base table by a supporting portion of the base table to be rotatable in an indexing manner about a rotating shaft inclined upward toward the front end thereof at 45.degree. to the rotating shaft of the spindle. A turn table is provided on the support to be rotatable in an indexing manner about a rotating shaft at 45.degree. to the rotating shaft of the support, and a tool magazine for storing a plurality of tools to be mounted on the spindle is disposed near the column. At least a part of the supporting portion of the base table for supporting said support is disposed between the post portions of the column.

The machine tool comprises, mounted by journals (7,7) between two strong uprights (1,2), a cradle (6) which pivots about a pivot axis and carries a plate (15) which may be driven in rotation, and a general slide (3) mounted on the uprights and supporting a saddle carrying a carriage which is vertically movable and provided with a single tool spindle (13) which is capable of receiving, from a tool changer, either milling or drilling tools, or turning or boring tools, said spindle being thus capable of being moved toward the workpiece to be machined carried by the plate. An exterior power motor (32) drives the plate (15) through a transmission extending through one of the journals of the cradle.

A machine tool module has a platen supported on a track above a metal-removing tool. A workpiece is placed on the platen at a loading station at one end of the track. A drive is provided to move the platen from the loading station to the metal-removing station where the tool removes material from the workpiece and then to an unloading station at the opposite end of the track. After the workpiece is unloaded, the platen is moved back to the loading station. A workpiece loading elevator is provided at the loading station and a workpiece unloading elevator is provided at the unloading station. Two such machine tool modules may be placed end-to-end so that a workpiece on the platen of one module may be transferred to the platen on the other module for machining by both modules in sequence.