Roller care commences
the day new rollers arrive from the supplier. Manufactures
usually recommended against storing new rollers. If
possible, put them to immediate use, which offers at least
one important benefit and two safeguards for the
lithographer determined to continue an effective roller
maintenance programme. If possible, locate the storage rack
in the pressroom, eliminating the time needed to adjust to
its temperature and humidity.
Placing new rollers
into immediate use guarantees the longest possible on-press
mileage from them. The synthetic rubber material will
experience deterioration prior to the roller’s first
printing assignment.
The press operator
will have an opportunity to examine the rollers for
roundness, evenness of caliper or diameter, possible core
distortions and durometer (hardness)
Each of these factors
bears on the life span and efficiency of a lithographic
roller. Discovering any deficiencies as soon as possible
will ensure against future downtime and roller-related
presswork problems to enable the operator to return
defective rollers to the manufacturer earlier rather than
later.
In addition, depending
on the urgency of roller replacement request as perceived by
the manufacturer, a new or replacement roller may not have
received the normal aging or stress relief measures prior to
the finishing process. Such a roller almost invariably
develops high or low spots if left in storage for any length
of time between its receipt and its initial use.
It may prove
expedient, nevertheless, to store new rollers at least
temporarily before putting them on the press. If so, be sure
to leave the rollers wrapped in the special paper provided
to protect them from sunlight, ozone and airborne
contaminants.
The location of the
storage rack also will affect the longevity and efficiency
of a roller- old or new- left off the press for extended
periods of time. If possible, locate the storage rack in the
pressroom, eliminating the time needed to adjust to
pressroom temperatures and humidities prior to installation
on the press. Avoid situating the storage rack near an ozone
producing electric motor or close to any source of high
heat.
The design of the
storage rack also is important to the well being of rollers.
Storage racks may be constructed to hold small rollers by
the ends of their shafts; large, heavy rollers fare better
if stored vertically.
Vertical storage of
rollers prevents the rubber of composition material from
separating from the core. Rollers stored horizontally should
be turned 180 degrees periodically to prevent the
"storage sag" rollers may experience over time
while in storage.
The storage rack also
should provide ample clearance between the rollers and any
part of the rack or of any nearby structure or machinery.
Probably the most common cause of low spots in offset
rollers is allowing them to rest for prolonged periods while
in contact with a solid surface or with another roller.
Some minimal
preparation of a roller going into storage helps prevent
roller deterioration or damage. It is vital to clean a
roller taken from the press and slated for storage. Be sure
to remove all traces of ink. If necessary, use a deglazing
compound on the roller to lift any film of hardened ink and
gum.
It also pays to
protect a roller earmarked for lengthy storage. Wrap it in
heavy paper or apply a film of non-detergent grease or
roller lubricant to the roller’s surface. The film of
lubricant will protect the roller from the harmful
consequences of any humidity/temperature fluctuations in the
storage area.
A chart kept near the
storage rack will prove helpful in keeping track of a
roller’s age and length of storage. The chart should list
the date of purchase of arrival of a new or reconditioned
roller, the date of its consignment to storage and a simple
one-to-five rating of the roller’s condition at the time
of storage.
It is important to
guard against careless handling of rollers being prepared
for storage. While not the primary press rollers, rollers
kept in storage nevertheless comprise important adjuncts to
the printing process and are vital to the continued
proficient operation of the pressroom. They must be ready
for immediate use on the press in case of damage or
functional failure of one of the newer rollers.
Avoid banging a roller
against a solid object, especially against sharp table
corners, workbenches and projections of machinery. The
synthetic rubber material comprising the roller’s pliable,
laminated outer layers easily can suffer irremediable damage
- permanent low spots may result from heavy blows.
All press rollers
should either be on the press in use or in the storage rack,
except when removed from the press for purposes of cleaning
or examination. A roller left untended on a workbench or
left learning a wall, table or piece of machinery is
particularly subject to damage. A roller thus left
accidentally for any prolonged period of time should be
thoroughly examined for any signs of damage.