Unbalance in turning operations

Application

In a turning operation, the tool is in a fixed position, whereas the rotary table and the clamped workpiece rotate. Depending on the size of the workpiece, the mass that is set in rotation can be very large. As the workpiece rotates, it creates an outward centrifugal force.

The control offers functions to detect the unbalance and support you in compensating for it.

Description of function

 
Machine

Refer to your machine manual.

Unbalance functions are not required and available on all machine tool types.

The unbalance functions described here are basic functions that are set up and adapted to the machine by the machine manufacturer. The scope and effect of the described functions may therefore vary from machine to machine. The machine manufacturer may also provide different unbalance functions.

Unwucht

The centrifugal force that occurs basically depends on the rotational speed, the mass and the unbalance of the workpiece. A body with an uneven mass distribution that is put into rotary motion produces an unbalance. If the mass object is rotating, this creates outward-acting centrifugal forces. If the rotating mass is evenly distributed, the centrifugal forces cancel each other out. You compensate for the arising centrifugal forces by attaching balancing weights.

With Cycle 892 CHECK UNBALANCE you define the maximum permissible unbalance and the maximum shaft speed. The control monitors these entries.

Cycle 892 CHECK UNBALANCE

Unbalance monitor

The Unbalance Monitor function monitors the unbalance of a workpiece in turning mode. If a maximum unbalance limit specified by the machine manufacturer is exceeded, the control issues an error message and initiates an emergency stop.

In addition, you can further decrease the permissible unbalance limit by setting the optional machine parameter limitUnbalanceUsr (no. 120101). If this limit is exceeded, the control issues an error message. The control does not stop table rotation.

The control automatically activates the Unbalance Monitor function when you switch to turning mode. The unbalance monitor is active until you switch back to milling mode.

Switching the operating mode with FUNCTION MODE

Notes

 
Warning
Caution: Danger to the operator and machine!
Very high physical forces are generated during turning, for example due to high rotational speeds and heavy or unbalanced workpieces. Incorrect machining parameters, neglected unbalances or improper fixtures lead to an increased risk of accidents during machining!
  1. Clamp the workpiece in the spindle center
  2. Clamp workpiece securely
  3. Program low spindle speeds (increase as required)
  4. Limit the spindle speed (increase as required)
  5. Eliminate unbalance (calibrate)
  • The rotation of the workpiece creates centrifugal forces that lead to vibration (resonance), depending on the unbalance. This vibration has a negative effect on the machining process and reduces the tool life.
  • The removal of material during machining will change the mass distribution within the workpiece. This generates the unbalance, which is why an unbalance test is recommended even between the machining steps.
  • To compensate an unbalance, several balancing weights at different positions may be required.