CNC Tool Changer of HG’s Machining Center
A CNC tool changer improves the efficiency of a CNC manufacturing process by eliminating the need for human input to change the tool.
A CNC tool changer is a device that can store different tools in the tool magazine and change tools automatically with the help of a short G-code. It reduces machine cycle time by eliminating the need to change tooling for multiple tasks manually.
What is a CNC Tool Changer?
CNC tool changers allow a CNC machine to perform different machining operations in a single run, without the need for stopping the machine to manually change the cutting tool for different operations.
As a result, it enhances the productivity of the process and eliminates human errors such as misaligned tool installation, which can affect the machining quality.
Apart from improving the overall production efficiency, the device also increases its tool-carrying capacity for performing more intricate operations that require different tooling.
In general, a CNC tool changer system consists of the following parts.
Part | Function |
Tool magazine | Indexable storage unit for multiple tools. |
Tool holders | For holding different types of tools. |
Automatic tool changer | Removes the current tool from the holders attached to the machine spindle and replace it with the new tool according to the CNC program. |
Coding rings of tools and their systems | For recognizing the exact tool according to the program. |
The ATC picks the tool automatically from the magazine according to the CNC program and inserts the desired tool (mounted in uniform holders) in the chuck or tool holder of the CNC machine being operated.
Different tool holders are suitable for holding different types of cutting tools used for various operations like face milling, peripheral milling, thread milling, drilling, reaming, tapping, turning, boring, etc.
Holder type | Purpose |
Arbor-type holder | For holding an arbor-type cutter which is required for face milling and end milling. |
Positive lock holder | For holding shank mills |
Straight shank collet holder | For holding tools for drilling, reaming, and boring. |
Compression and tension collet holders | For holding tools for tapping. |
Upon completion of the operation, the tool is either returned to the magazine or replaced according to the CNC program.
Types of CNC Tool Changers
CNC tool changers can be of five types based on the arrangement of the magazine and the number of tools.
Type | Tool holding capacity |
ATC system with a gripper arm | 32 tools maximum |
ATC system with a rotary drum. | 30 tools maximum |
ATC system with a chain magazine | Minimum 32 and is capable of holding more than 100 tools. |
ATC system with disc magazine | Minimum 32 and maximum 64 tools |
ATC system with Turret Head | Maximum 8 tools. |
ATC System with a Rotary Drum (Drum Type Tool Magazine) for HG's Machining Centers
This type of ATC operates with 30 tools (maximum) placed in a magazine at the periphery of a rotating drum.
The system consists of a cam-based gearbox responsible for changing the tools using roller gear and grooved plate cams.
Owing to their shorter unit length and simplistic structure, ATC systems based on rotary drums have faster operating time, better efficiency, and are also cost-effective.
As a result, drum-type tool changers are best suited for industrial applications where high productivity is desirable.
Advantages of Using a CNC Tool Changer
Increases Productivity of the CNC Machine
Automatic changing of the tools decreases the cycle times by eliminating the time required for manual tooling and thus increases the rate of productivity of the machine.
As a result, CNC tool changers are recommended for industrial applications where high productivity leads to high profit.
Reduction of Labor Costs
Using CNC tool changers, the machine can perform multiple functions automatically, thereby eliminating the need for an operator for tool change.
This reduces labor costs while also improving shop floor safety by reducing any accidents caused by manual errors.
Increase in Tool Storing Capacity of the Machine
The tool magazines can store tools ranging from 8 to 100 based on the type of ATC.
Such an arrangement allows the machine to perform intricate and complex operations without frequent human input.
Better Process Repeatability and Product Quality
Installing ATC eliminates the operator intervention during the process and thus reducing human error involved and increasing the process repeatability.
The above factors enhance the quality of the final product obtained via the process.
Wide Range of Sizes
The ATCs are available in a wide range of sizes and types from which you can select based on your requirement.
Making CNC tool changers affordable for almost any scale of business application.
Better Worker Safety
Incorporating ATCs allows the CNC operators and CNC machinists to supervise the process instead of direct participation, thus improving their safety.
Generally, a CNC machinist is responsible for the initial setup of the process, while a CNC operator ensures that the process is followed accordingly.
How Does a CNC Tool Changer Work?
The basic working of the CNC tool changer can be explained by the arm-based system.
After acquiring the tool change command via the program, the tool to be changed will be moved to a fixed position known as the "tool change position."
The ATC arm, swivels between the turret and the magazine, picking the tool from the tool change position.
The grippers on both sides of the arm can rotate 90°, by virtue of which the tools are delivered to the turret front face.
One of the grippers is responsible for picking up the old tool from the turret, while the other picks up the newly commanded tool from the magazine.
Subsequently, the arm rotates 180° and places the tools in their respective position.
The arm and spindle's relative movement can also have several variations.
For instance, in the case of a quill-type spindle, the spindle moves towards the arm gripper to accept or replace the tool.
Whereas for the regular spindles, the arm itself pursues the in and out motion for inserting or extracting the tools.
However, In the chain type ATC, the tools are either coded physically or in the magazine loaded with the tool.
Based on the program provided to the CNC controller, the chain driver motor rotates clockwise or anticlockwise to position the tool at the desired position.
The addition of a tool changer increases the difficulty of CNC programming, as it requires additional codes for tool change.
T-codes are commonly used for tool selection. For instance, T26 in the program means select tool number 26.
The M06 command in the program instructs the ATC for a tool change, and it needs to be executed before the T command.
Things to Consider While Operating an ATC.
Tool Length
Tool length plays an important role in the safe operation of ATC.
When using a tool larger than the standard permissible length, it is advised to monitor the Z-axis clearance as the contact between the tool and the part to be machined, can damage the fixture.
In case the tool is obstructed during operation, it is recommended to immediately activate the emergency stop to prevent any fatal damage.
Tool Weight
In ATC, the maximum permissible tool weight includes the weights of the holder, collets, and all their parts.
The individual weight of the tool is always lighter than the permissible weight.
On exceeding the permissible weight, the tool changer might fail to anticipate the predefined machining center, leading to process inaccuracy.
