Skip to main content

Automatic tool changers (ATCs) are used in computer numerical control (CNC) machines to increase machine productivity and tool transferability. ATC quick-change tools reduce non-productive time. They are often used to improve a machine’s ability to use multiple tools. They are also used to replace worn or damaged tools. This is another step toward full automation. How does the automatic tool changer function work, and what does it consist of? What are the advantages of using an automated tool changer? We write about it below! 

CNC and the automatic machine tool changer 

Simple CNC machines use a single tool. The turret has access to a large number of devices. However, if more tools are needed, an ATC is required. The tools are stored in tool magazines. This allows the machine to use many tools without operator intervention. The main components of an automatic tool changer are: 

  • base, 
  • clamping arm, 
  • tool holder, 
  • carrier arm and tool storage. 

Although the ATC improves the reliability, speed, and accuracy of the machine, the design itself presents more challenges than manual tool changing. For example, the tool being used must be easily centered and gripped by the tool changer, and there should be an easy way to ensure that the mechanism disengages itself. The tools used in ATCs are mounted in specially designed tool holders.

Types of the tool changer

Depending on its shape, a tool changer can be of two types:

1) Use a drum changer when the number of tools is less than 30. Tools are stored around the perimeter of the drum.

 2) Use a chain changer when the number of tools is more than 30 (This number varies by design and manufacturer. Note that the number of drum tools is less than the chain). However, in this case, the speed of the search tool will be reduced.

Automatic tool change mechanism

When a tool change command is received, the tool to be changed is in a fixed position, called the „tool change position.” The ATC arm reaches this position and picks up the tool. The robotic arm rotates between the machine tower and the magazine. It has a clamp on each side. Each jaw can be pivoted 90° to deliver the tool to the front of the turret. One removes the old tool from the turret, and the other removes the new tool from the magazine. Then rotate 180° and place the tool in the desired position.

Tool changers on sheet metal machines

ATC was initially used on chip conveyors such as mills and lathes. Automatic tool-changing systems have also found their way into sheet metal machinery. A press brake has an integrated CNC control that moves the punch according to the size of the part. Automatic tool changing on press brakes is limited to machines integrated into robotic bending cells. Often the 6-axis robots used to handle semi-finished parts are also responsible for changing punches and dies between batches. Starting in the 1920s, automatic tool changers appeared on non-robotic press brakes. The most common configuration is a tool holder on the side of the press brake with a carriage to pick up tools and place them where they are needed. This reduces the physical burden on the operator and increases overall productivity. 

Tool changer functions

Using automatic changers increases production time and reduces non-production time. It provides tool storage and automatic return to the machine when the required operations are completed. It increases machine flexibility, makes it easier to change heavy and oversized tools, and enables automatic cutting-edge updates.

Cutting tools for CNC machines

Three basic cutting tool materials are high-speed steel, tungsten carbide, and ceramic. High-speed steel is typically used for aluminum and other non-ferrous alloys, while tungsten carbide is used for high-silicon aluminum, steel, stainless steel, and rare metals. Ceramic inserts are used for hard steels and rare metals. Carbide tools are becoming the tool of choice in many CNC applications. To take full advantage of CNC machine tools, attention must be paid to the selection and use of tools, namely tool holders, tools, and workpiece clamping devices. CNC machine tools need to be changed quickly to reduce cutting, setting, and resetting time outside the machine, with a high degree of interchangeability, increased reliability, and rigidity.