April 2013 1.5 New functions 39
Only CC 6xxx: Active Chatter Control (ACC) (software option 145)
Strong forces come into play during heavy cutting (power milling). These
forces are transmitted between the milling spindle and the machining axes
via the tool and the workpiece. Depending on the tool spindle speed, the
resonances in the machine tool and the removal volume (metal-removal rate
during milling), the tool can sometimes begin to "chatter." This chattering
places heavy strain on the machine, and causes ugly marks on the
workpiece surface. The tool, too, is subject to heavy and irregular wear from
chattering. In extreme cases it can result in tool breakage.
To reduce a machine's inclination to chattering, HEIDENHAIN offers
software option 145 Active Chatter Control (ACC). The use of this option is
particularly advantageous regarding the attainable metal removal rate during
heavy cutting. Depending on the type of machine, the metal removal rate
can be increased significantly within the same machining time. Software
option 145 must be enabled in order to be able to use ACC. ACC must then
be enabled for all machining axes via MP2700 bit 4. The machining axes are
usually the axes X, Y, and Z. Also, for all tools that are used for heavy cutting,
"1" must be entered in the ACC column of the tool table, and the number of
tool teeth in the CUT. column.
If a tool with active ACC function is inserted, a damping signal reducing the
chatter tendency is automatically added in the control loop.
You have the additional possibility of using machine parameter MP2710 to
influence the weighting of the damping signal between the X, Y, and Z axes.
In this machine parameter you can select the axis to which the higher-
weighted damping signal is to be applied.
Besides this automatic function, you have the option of creating an ACC
parameter file with TNCopt 7.0 and transfer it to the control. Since every tool
influences the chatter characteristics of the cutting process, an individual file
can be created for each tool. Alternatively you can also create a machine-
specific file. The respective chatter frequency range and the intensity of the
damping signal can be set using the parameter files. If a tool with active ACC
function is inserted, the NC first automatically searches for a tool-specific
parameter file. If no such file is available, it searches for a machine-specific
file. If this is not available either, ACC operates in automatic mode.
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