The Automatic Tool Changer (ATC) is used in computer numerical controls for CNC machine tools to increase the machine's efficiency and tool transfer capabilities. Quick-change ATC tools reduce non-productive time. They are often used to enhance the machine's ability to use multiple tools. They also serve to replace worn or damaged tools. This is another step towards full automation. How does the automatic tool changer function work and what does it involve? What are the benefits of using an automatic tool changer and why choose professional equipment? We write about this below!
Automatic tool changer for CNC machine
Simple CNC machines and measuring tools use a single tool, ensuring the correct measurement result. The turret has access to a large number of tools. However, if more tools are needed, an ATC is required. Tools are stored in tool warehouses. This allows the machine to use a large number of tools without operator intervention. The main elements of the automatic tool changer are:
- base,
- mounting arm,
- tool handle,
- carrying arm and tool storage.
Although ATC improves the reliability, speed, and accuracy of the machine, the design itself poses more challenges than manual tool changing. For example, the tool in use must be easily centered, easily gripped by the tool changer, and there should be an easy way to ensure that the tool will turn off by itself. Tools used in ATC are mounted in specially designed tool holders.
Types of tool changers
Depending on the shape, the 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 entire circumference of the drum.
2) Use the chain changer when the number of tools is greater than 30 (this number varies depending on the project and manufacturer. Remember that the number of drum tools is smaller than the chain). However, in this case, the speed of the search tool will be reduced.
Automatic tool exchange mechanism
After receiving the tool change command, the tool to be changed is located in a predetermined position, called the "tool change position". The ATC arm reaches this position and lifts the tool. The robot arm rotates between the machine tower and the magazine. It has a clamp on each side. Each jaw can be rotated 90° to deliver the tool to the front of the tower. One of them 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. The appropriate tools will allow this.
Tool changers on sheet metal processing machines
ATC was originally used in chip conveyors, such as mills and lathes. Automatic tool exchange systems have also found application in sheet metal processing machines. The press brake has integrated CNC machine control, which moves the punch according to the size of the part. Automatic tool change on press brakes is limited to machines integrated into robotic bending cells. Often 6-axis robots used for handling semi-finished products are also responsible for changing punches and dies between batches. Starting from the 1920s, automatic tool changers appeared in press brakes without robots. The most popular configuration is a tool holder on the side of the press brake with a trolley for lifting tools and placing them where they are needed. This reduces the physical strain on the operator and increases overall efficiency. These are some of the many solutions that are essential for a professional CNC industry company.
Functions of the Tool Changer
Using automatic tool changers extends production time and reduces non-production time. It provides tool storage and automatic return to the machine after the required operations are completed, increasing the machine's flexibility, facilitating the exchange of heavy and large tools, and enabling automatic updating of the cutting edge.
Cutting Tools for CNC Machines
There are three basic types of materials for cutting tools: high-speed steel, tungsten carbide, and ceramics. 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. Tools made of sintered carbides are becoming the tool of choice in many CNC applications. To fully utilize CNC machine tools, attention should be paid to the selection and application of tools, namely tool holders, tools, and devices for securing the workpiece. CNC machine tools must be quickly replaced to shorten cutting time, setting, and resetting outside the machine, with a high degree of interchangeability, increased reliability, and high rigidity.
How does the automatic tool changer work?
Once configured on the CNC machine, the automatic tool changer performs a quick set of tool change steps. Here's how it works:
- The tool change command is issued to the machine by the computer.
- The tool being replaced takes a fixed position, called the "tool change position".
- The ATC spindle moves to this position to pick up the tool.
- The axis moves between tables/rotary tables to pick up/bend tools.
- Internally, the spindle opens or closes the holder to change the tool before returning to work.
- Within a few seconds, the ATC can perform automatic tool changes (except for programmed tool changes) without human intervention.
What are the benefits of an automatic tool changer?
Automatic CNC tool changers have many significant advantages on the production floor, including:
- Switch between a large number of tools without human intervention.
- Improve the accuracy of the device and workshop.
- Definitely reduce downtime and total production time.
- Increase the capacity of the tool warehouse.
- Provides greater versatility of the machine.
- Ensures work safety.
- Easy exchange of larger and heavier tools.
- Improves performance.
- You can reduce labor costs.
- The edge finish is better due to the choice of a more suitable tool for the process.