Working of Automatic Tool Changer (ARC):

Updated: Sep 24, 2021

CNC machines are designed to perform a number of operations in a single setting of the job. A number of tools may be required for making a complex part. In a manual machine, tools are changed manually whenever required. In a CNC machine, tools are changed through programme instructions. The tools are fitted in a tool magazine or drum. When a tool needs to be changed, the drum rotates to an entry position, approaches the odd tool and pulls it. Then it again rotates the new tool, fits it and then retracts. It is a typical tool changing sequence of an automatic tool changer.

The types of ATC are given below:

  1. Drum type.

  2. Chain type.

Drum Type:

For holding small number of tools not more than 30, the speed of both drum and tool is faster.

Chain Type:

For more number of tools, speed is less. As soon as the tool selection command is received by the system, the selected tool comes to a fixed place known as tool change position. The selected tool is transferred to the spindle from magazine after the previous tool transferred to the magazine from spindle. It is called tool change cycle.


  1. Lines change seconds instead of hours.

  2. It increases operator safety by changing tool automatically.

  3. The tool changing is easy in seconds for maintenance and repair.

  4. It increases the flexibility.

  5. Heavy large multi-tools that are automatically exchanged.

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