The portal frame is composed of upright columns and top beams, and there are beams in the middle. The beam can move up and down along the guide rails of the two columns. There are 1 to 2 milling heads with vertical spindles on the beam, which can be moved laterally along the beam rail. A milling head with a horizontal main shaft can also be installed on the two uprights separately, which can move up and down along the upright rails. These milling heads can process several surfaces simultaneously. Each milling head has a separate motor (power up to 150 kilowatts), variable speed mechanism, operating mechanism and spindle components. The horizontal long bed is provided with a movable working table and covered with a protective cover.

During china cnc machining, the workpiece is installed on the worktable and longitudinal feed motion is performed accordingly. There are some variants of gantry milling machine to adapt to different processing objects.

The shape of the gantry milling machine is similar to the gantry planer, the difference is that its beam and column are not equipped with a planer tool holder but a milling tool holder with a spindle box, and the reciprocating motion of the longitudinal table of the gantry milling machine is not the main movement, but the Give motion, and the rotary motion of the milling cutter is the main motion. The gantry milling machine is composed of a portal frame, a bed table and an electrical control system.

Gantry milling machine is referred to as gantry milling, which is a milling machine with portal frame and horizontal long bed. The gantry milling machine can use multiple milling cutters to process the surface at the same time, and the machining accuracy and production efficiency are relatively high. It is suitable for processing the plane and slope of large workpieces in batches and mass production. CNC gantry milling machine can also process space curved surface and some special parts.