Warner Electric PB-1525 - Manual (Page 6)

6 Warner Electric • 800-825-9050 P-209 • 819-0517
Burnishing and Maintenance
Burnishing
Intimate metal to metal contact is essential
between the armature and the metal rings (poles)
of the magnet or rotor. Warner Electric clutches
and brakes leave the factory with the friction mate-
rial slightly undercut to assure good initial contact.
Normally, the desired wearing-in process occurs
naturally as the surfaces slip upon engagement.
The time for wear-in, which is necessary to obtain
the ultimate torque of the unit, will vary depending
on speed, load, or cycle duty.
If maximum torque is required immediately after
installation, the unit should be burnished by slip-
ping the friction surfaces together at reduced volt-
age. It is recommended that the burnishings be
done right on the application, if at all possible.
Burnishing at high speed will result in a smoother
wear-in pattern and reduce the time for burnishing.
The voltage should be set at approximately 30% or
40% of the rated value.
The unit should be cycled on and off to allow suffi-
cient time between slip cycles to prevent overheat-
ing.
When a Warner Electric brake or clutch is
properly assembled and installed, no further servic-
ing, lubrication, or maintenance should be required
throughout the life of the unit.
Maintenance
Wear Pattern: Wear grooves appear on the arma-
ture and magnet surfaces. This is a normal wear
condition, and does not impair functioning of the
unit. Normally, the magnet and armature, as a mat-
ing pair, will wear at the same rate. It is the usual
recommendation that both components be
replaced at the same time.
Remachining the face of a worn armature is not
recommended. If a replacement armature is to
be used with a used magnet, it is necessary to
remachine the worn magnet face. In refacing a
magnet: (1) machine only enough material to clean
up the complete face of the magnet; (2) hold the
face within .005" of parallel with the mounting
plate; and (3) undercut the molded facing material
.002" - .004" below the metal poles.
Heat: Excessive heat and high operating
temperatures are causes of rapid wear. Units,
therefore, should be ventilated as efficiently as pos-
sible, especially if the application requires fast,
repetitive cycle operation.
Foreign Materials: If units are used on
machinery where fine, abrasive dust, chips
or grit are dispelled into the atmosphere,
shielding of the brake may be necessary if
maximum life is to be obtained.
Where units are used near gear boxes or
transmissions requiring frequent lubrication, means
should be provided to protect the friction surfaces
from oil and grease to prevent serious loss of
torque.
Oil and grease accidentally reaching the friction
surfaces may be removed by wiping with a rag
dampened with a suitable cleaner, which leaves no
residue. In performing this operation, do not drench
the friction material.
If the friction materials have been saturated with oil
or grease, no amount of cleaning will be completely
effective. Once such a unit has been placed back
in service, heat will cause the oil to boil to the sur-
face, resulting in further torque loss.
Torque Loss: If a brake or clutch slips or loses
torque completely, the initial check should be the
input voltage to the magnet as follows:
90-Volt Series: Connect a DC voltmeter with a
range of 0-100 or more directly across the
magnet terminals. With the power on and the