ATC(Auto Tool Changer) is the device to change tools automatically. It consists of a magazine that stores tools, a middle arm that takes tools from the magazine, and an ATC arm that changes tools. NC codes command the storage of tools, the rotation and positioning of the magazine, and the changing of tools for the main axis and the magazine.
ATC stands for Auto Tool Changer. This device is always attached to the machining center and changes tools having different shapes and diameters automatically by the command from NC data. ATC consists of a magazine that stores tools, a middle arm that takes tools from the magazine, and an ATC arm that changes tools. There are many positions to install this device, such as above the main axis head, above the column, on the side of the column, or separated from the machine. Also, for magazines there are various shapes, such as cylindrical, conical, elliptical, and rectangular depending on the capacity of storage, the position to be installed, and the availability of space.
To change tools, the tool magazine is rotated and the tool needed is moved to the changing position. Next, the middle arm takes out the tool. The ATC arm is rotated to grab the tool held by the middle arm and the tool attached to the main axis. Then, the ATC arm pulls out the tool from the main axis and rotates 180 degrees to attach the new tool to the main axis. The old tool is stored in the magazine by the middle arm.
There are two methods to select tools. One is called Sequential method, and the other is called the Random method. For the Sequential method, tools are arranged in the order to be used and changed in that order. For the Random method, tools are changed randomly regardless of the order of the arrangement. Lately, the random shortcut method is mainstream. For this method, tools are selected randomly and the magazine rotates to the direction which is closer to the tool change position.
Some ATC's which have a small magazine have no middle arm, and tools are taken out / changed by the ATC arm directly. Some ATC's do not use an ATC arm, and the main axis moves to change a tool.