
B–62073E/04
3. INSTALLATION
30
The CNC has been steadily reduced in size using surface–mount and
custom LSI technologies for electronic components. The CNC also is
designed to be protected from external noise. However, it is difficult to
measure the level and frequency of noise quantitatively, and noise has
many uncertain factors. It is important to prevent both noise from being
generated and generated noise from being introduced into the CNC. This
precaution improves the stability of the CNC machine tool system.
The CNC component units are often installed close to the parts generating
noise in the power magnetics cabinet. Possible noise sources into the
CNC are capacitive coupling, electromagnetic induction, and ground
loops.
When designing the power magnetics cabinet, guard against noise in the
machine as described in Subsections 3.6.1 to 3.6.5.
The cables used for the CNC machine tool are classified as listed in the
following table:
Bind the cables in each group as described in the action column.
Group Signal line Action
A
Primary AC power line
Bind the cables in group A
p
arately (Note 1) from grou
p
Secondary AC power line
separa
e
y
o
e
rom groups
B and C or cover group A with
an electromagnetic shield(Note
AC/DC power lines (containing
the power lines for the servo
and spindle motors)
an e
ectromagnet
c s
e
ote
2).
See Section 3.6.4 and connect
spark killers or diodes with the
AC/DC solenoid
spark killers or diodes with the
solenoid and relay.
AC/DC relay
B
DC solenoid (24 VDC)
Connect diodes with DC
DC relay (24 VDC)
.
Bind the cables in group B
separately from group A or
cover group B with an
DI/DO cable between the CNC
and power magnetics cabinet
.
Separate group B as far from
Group C as possible.
DI/DO cable between the CNC
and machine
It is more desirable to cover
group B with the shield.
3.6
ACTION AGAINST
NOISE
3.6.1
Separating Signal
Lines