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Chapter 10 Adjustment
10–17
(3) Adjusting the lost motion compensation timing
If the speed loop gain has been lowered from the standard setting value because the machine
rigidity is low or because machine resonance occurs easily, or when cutting at high speeds, the
quadrant protrusion may appear later than the quadrant changeover point on the servo control. In
this case, suppress the quadrant protrusion by setting the lost motion compensation timing
(SV039: LMCD) to delay the LMC compensation.
<Adjustment method>
If a delay occurs in the quadrant protrusion in the circle or arc cutting as shown below in respect
to the cutting direction when CNC sampling measurement (DBB measurement) or actual cutting
is carried out, and the compensation appears before the protrusion position, set the lost motion
compensation timing (SV039:LMCD).
While measuring the arc path, increase LMCD by 10ms at a time, to find the timing that the
protrusion and compensation position match.
Before timing delay compensation After timing delay compensation
No. Abbrev. Parameter name Unit Explanation Setting range
SV039 LMCD Lost motion
compensation timing
ms Set this when the lost motion compensation timing does not
match. Adjust while increasing the value by 10 at a time.
0 to 2000
(ms)
When the LMCD is gradually raised, a two-peaked contour may occur at the motor FB position
DBB measurement. However, due to the influence of the cutter diameter in cutting such as end
milling, the actual cutting surface becomes smooth.
Because satisfactory cutting can be achieved even if this two-peaked contour occurs, consider
the point where the protrusion becomes the smallest and finest possible without over
compensating (bite-in) as the optimum setting.
Cutter center path
Actual cutting surface
Cutting direction
Quadrant changeover point
Point of LMC compensation execution
Cutter diameter
A
fter
compensation
Cutting
direction