Leadscrew Backlash Compensation - Fagor CNC 8055i FL EN Installation Manual

I n s t a l l a t i o n m a n u a l
7.5.6

Leadscrew backlash compensation.

On this CNC, the leadscrew backlash may be compensated for when reversing the direction of
movement. Leadscrew backlash is defined with axis parameter BACKLASH (P14).
Sometimes, an additional velocity command pulse may also be needed to recover the possible
backlash when reversing the axis movement. The additional velocity command pulse may be either
rectangular or exponential.
If the duration of the rectangular pulse is adjusted for low speed, it may be too high for high speed
or not enough for low speed when adjusted for high speed. In these cases, it is recommended to
use the exponential type that applies a strong pulse initially and decreases in time.
axis parameter BACKNOUT (P29) sets the value of the additional velocity command and axis
parameter BACKTIME (P30) indicates the duration of this additional command pulse and general
machine parameter ACTBAKAN (P145) indicates the type of backlash peak applied.
Cutting the compensation peak off.
Every time the axis movement is inverted, the CNC will apply to that axis the velocity command
corresponding to the movement plus an additional velocity command (to make up for backlash). This
additional velocity command is eliminated (peak compensation cutoff) depending on the values of
the following parameters:
General parameter BAKTIME (P30), general parameter ACTBAKAN (P145) and axis parameter
PEAKDISP (P98).
Hysteresis in the reversal movement compensation command
Axis machine parameter REVEHYST (P99) is used to be able to control when the compensation
should really be applied after detecting a movement reversal and not applying it every time a reversal
command is received.
This feature should only be applied in situations where the moving direction reversals are very small
(e.g. ±1dµm) The purpose is to prevent the reversal compensation to be applied in these situations,
because it can cause slight machining marks (ridges) on the part.
7.
CNC 8055
CNC 8055i
S : V02.2
OFT X
·327·