Solution to Tool Jamming in a VMC Tool Magazine

Vertical machining centers (VMCs) are equipped with CNC control systems, tool magazines, and automatic tool changers (ATC). These allow the completion of multiple operations—such as milling, boring, drilling, reaming, and tapping—in a single setup. The CNC system, tool magazine, and ATC are key components enabling the VMC’s exceptional machining capabilities. Among them, the tool magazine and ATC are what primarily distinguish VMCs from other machine tools. These components are used frequently, and if they are not maintained properly or are used for extended periods, tool jamming in the magazine may occur.


Causes of Tool Jamming in a VMC and Solutions:
    1.    Incorrect Spindle Orientation Angle
Misalignment of the spindle orientation angle is often caused by machine collisions or issues with the spindle’s timing belt. If the orientation is off, it can result in tool change malfunctions or jamming.
    2.    Abnormal Second Tool Change Reference Point
Machine crashes, often due to operator error, can cause the tool change reference point to shift. This manifests in the tool arm failing to properly remove or insert tools, leading to tool jamming. Over time, this can also damage the tool arm.
    3.    Unstable Air Pressure or Excess Moisture in the Air Supply
Pneumatic components may fail if the air pressure is unstable or if there is excessive moisture in the air line, contributing to tool magazine malfunctions.


Tool Jamming Situations and Solutions:

There are generally two types of tool jamming scenarios:
    •    The tool has not been pulled out, or
    •    The tool has already been pulled out.

Here are the steps to resolve tool jamming:
    1.    Release the Brake on the Tool Arm Motor
Use an adjustable wrench to manually rotate the hex on the motor shaft. Rotate in the same direction as the stuck arm to disengage the tool arm from the spindle of the CNC machine.


    2.    Be Cautious of Falling Tools
As the tool arm detaches from the spindle, if a tool is still clamped in the spindle, you may hear air leaking—indicating the spindle is in a “tool release” state. Place a pad or protection under the spindle to catch the tool in case it drops.
    3.    Rotate the Tool Arm Through a Full Tool Change Cycle
Keep manually rotating the tool arm until it completes a full tool change motion. The tool arm has a reference (home) position, usually indicated by LEDs on the tool magazine panel. Typically, the center red light indicates the tool arm is at its home position.

    4.    Reset and Test
After resolving the tool jam, re-engage the brake on the tool arm motor. Switch the CNC to MDI mode, and attempt a tool change to ensure everything is functioning properly. Before resuming production, verify that all required tools are correctly loaded and the system is safe for operation.