There are three main types of Gantry Milling Machine in the industry which includes Conventional Gantry Type Milling Machine, Moving Gantry Machining Center and Fixed Gantry Machining Center. 

The Conventional Gantry Type Milling Machines are typically used for large-scale machining tasks that require heavy cutting, such as the production of large components for industries like aerospace, automotive, and shipbuilding. They are manually operated and have the advantage of versatility and the ability to handle oversized work-pieces that may not fit on smaller milling machines. Their operation requires skilled and experienced operators due to the manual control of the machine's movements.

The Conventional Gantry Type Milling Machine, often referred to as a Gantry Mill, is a large and powerful milling machinery used for precision machining of heavy and oversized work-pieces. It is characterized by its unique gantry-style structure. This kind of milling machine is typically operated manually, don’t have CNC Control System, with the operator manual controlling the machining process. 

There are three main types of Double Column Machining Center in the industry which includes Moving Gantry Machining Center, Conventional Gantry Type Milling Machine and Fixed Gantry Machining Center.

The most distinctive feature is the presence of two vertical columns that are widely spaced apart, creating a bridge-like structure. This design provides exceptional rigidity and stability, reducing vibrations and ensuring accurate machining. And the worktable is positioned between the two columns and is capable of supporting large and heavy work-pieces. It can move vertically (Z-axis) and horizontally (X-axis) to position the work-piece for machining.