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Selecting
Offset Printer Motor Drives
There are different methods that can be used to
drive Matthews offset printers. The most common way is to friction drive
it by the product that is being printed. Friction driven means that the
printer's blanket roll, upon contacting the product receives the driving
power necessary to revolve the printer. There is no direct connection,
other than the contact the blanket roll makes with the product. This is
an excellent choice for random printing and when the mark is not required
to be in precise registration with the product or hte mark center repeat
is not important.
 Matthews
offers various drive systems that can accommodate a wide range of applications.
The following list describes some of the typical applications where they
are used. The list does not attempt to capture all possibilities and is
for general information only. A Matthews representative will be glad to
discuss specific requirements or alternate drives.
In concluding,
there needs to be careful planning when selecting the printer and method
of drive. The number one question should be; What is it that you want
the printer to do? With this understood, the expected results should be
achieved.
Click on
the title below to jump to a specific motor drive description.
Electric
Motor Drive With Variable Speed Control
Normally used when a printer cannot be friction
driven adequately by the product. This can be due to product limitations
such as small diameter tubing, cable and similar products that do not
provide sufficient wrap-around at the blanket roll when printing linearly.
Products that are flexible and stretch when resistance is applied can
be another reason to consider using an electric motor drive.
Similar conditions
exist with flat material where there is insufficient driving force available
from the product itself. The motor drive becomes the power source and
can be adjusted manually to match the production line speed. The electric
motor provides a constant drive torque, runs consistently at slow speeds
and is quiet to operate.
Electric
motor drives are used on many off-line or stand-alone applications. The
offset printer and motor drive combinations can be tooled to mark individual
parts or automatic feed and eject
options can be furnished to increase production rates.
Air
Motor Drive With Air Pressure Regulated Control
Application criteria is similar to that of the
above. However, the air motor acts as a printer drive to assist and minimize
the friction drive requirements while not affecting print quality when
there is fluctuation in the production line speed. This is due to the
reduced torque produced by the air motor and its ability to continue operating
without damaging the internal parts.
Air motor
drive torque varies with the air pressure supply and it is not as effective
as the electric motor when operated at speeds lower than 25 RPM. There
is a low level sound present from the air passing through the exhaust
port when it is operating. A small muffler is used to reduce the sound
level. The speed is controlled using an air pressure of the regulator.
In addition, air motor drives are extremely safe in explosion-proof environments
due to the air-only requirements to operate.
Electric
Motor Drive With Line Speed Monitoring Option
This feature requires an input signal from the
customer's production line that automatically adjusts the motor speed
to maintain synchronization between the printer and the production line.
The quality of the mark is enhanced when this option is employed. Without
this option, it would require an operator to manually readjust the motor
speed control by using a tachometer to measure both the production line
speed and the printer speed.
The printer
speed would require adjusting if the two speeds vary. If this is not done,
the mark will smear, becoming difficult to read and blanket roll wear
can occur. By adjusting the automatic speed monitoring option the process
relies less on the operator to make manual adjustments.
Single
Revolution Clutch Option
When marking parts on-line that are spaced incrementally
a clutch can be furnished that will allow one mark per part. In most cases,
the customer furnishes a momentary electrical signal to the clutch solenoid
that unlatches the clutch for one complete revolution.
The printer
blanket roll will then remain in the stopped position until the next signal
is received. The clutch option is recommended for off-line marking operations
especially when marking individual parts that are loaded onto the marking
station manually. This feature provides ease of operation and the capability
to begin marking at the same start position each time.
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