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What Is An Automatic Tool Changer?

An automatic tool changer often referred to as an ATC, is used to improve both the production and the tool carrying capacity of a computerised numerical control or CNC machine tool. It does this by allowing the machine to work with various different tools. As such it is part of the process to achieve full automation.

Automatic tool changerGeneral Description

A simple CNC machine will be made to work with a single tool. More complex machines are capable of working with larger numbers of tools. However, for a machine to use more tools an ATC must be provided. The array of tools are stored within a magazine which allows the machine to access a wider variety of them without the need for an operator.

An automatic tool changer is generally comprised of a base, arms with a gripper, a tool holder and a support arm as well as the tool magazines. An ATC is capable of increasing the speed and accuracy as well as the reliability of a CNC machine but it does have certain requirements. Some of these include the need for the tools to be easy to centre as well as simple for the grabber arm to hold as well as easy to automatically disengage. To provide this, tools used in an ATC are usually held by specially designed tool holders.

Different Types of Automatic Tool Changer

ATCs come in two variants depending on the magazine’s shape. Some are on rotary holders on a turn table type setup with claws holding each tool in its own location. Some are straight static racks of tools that are mechanically much simple. High end milling machines can then have chain type tool holding stations when the tool count goes up into the 20’s and 30’s.

Automatic Tool Changer Mechanism

First the automatic tool changing command is given. The tool that is going to be changed moves into the tool change position. The ATC arm then moves into the position so it can pick up the tool. One gripper arm moves the new tool to the turret while a second removes the old tool.


The ATC works to significantly increase productivity by reducing the time the CNC machine spends idle. It allows for a large number of tools to be stored locally to the machine each of which is returned automatically when its task is complete. This also makes it much simpler to change large or heavy tools that would be otherwise difficult to handle.

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