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Norman G. Clark Announces: Contemporary Rotating Unions for Modern Printing Machines

Norman G. Clark Announces:

 

Contemporary Rotating Unions for Modern
Printing Machines

They
operate in the background, but without them the functionality of modern
printing machines would not be possible:

Rotating
unions.

 


Whether
sheet-fed offset printing, web offset or gravure printing, rotating unions are
the link between rotating rollers and the pipelines and hoses of the heating or
cooling circuit for maintaining the temperature of ink application rollers,
printing ink unit or dampening system.

 

Generally
speaking, temperature setting and keeping of constant temperatures in the above
mentioned assemblies are a material precondition for continuous and
reproducible quality at highest machine speed. This is also the key to
reduction of waste paper produced during start-up or production – a cost factor
which must not be disregarded.

 

Why
is the "rotating union" that important for this task?

As
it guides the medium into and/or out of the rotating part, its technology and
degree of development significantly affect the efficiency of the entire
machine:

 


Primarily by way of optimized flow channels and reduced turbulence which also
means a continuous temperature profile, i.e. increased quality with reduced
waste paper.


Secondarily by considering the required energy, as modern rotating unions
feature only minor pressure losses and reduced coefficients of friction so that
the pump and motor rating can be lower.

 

In
addition to the savings of costs, the reduced energy consumption also entails a
reduction of CO2, an important topic today.  Furthermore, the third aspect should not be ignored in this
consideration: The service life of a rotating union.

 

Especially
in this respect, chaff (low-cost product) is separated from wheat (branded
product) quickly.

 

It
is undisputed that each rotating unit which is based on the principle of the
"balanced mechanical seal" is a wear part, as the mechanical seals
are subject to wear although they are lubricated by the flow medium.

 

One
cost driver can be derived therefrom easily: How often does the service
department have to replace the rotating unions? Can this be affected in the
scope of the regular maintenance intervals of the machine or does it imply
nonscheduled (expensive) machine downtimes?

 

The
quality philosophy of manufacturers of branded products such as DEUBLIN includes
that the user has to deal with maintenance as rarely as possible, i.e. that
the service life is increased.

 

This,
however, requires consequent materials research in order to be able to use
highly wear-resistant material combinations for mechanical seals. Furthermore,
a high surface quality and concentricity of the mechanical seals are to be
achieved in the production process as they also immediately affect the service
life.

 

Low-cost
rotating unions often lack these features. Neither the material combination nor
the surface quality or the concentricity are designed to allow the operator
long intervals without maintenance.  In a
total-cost-of-ownership analysis which also includes machine downtimes and (frequent)
maintenance operations, the cost driver "low-cost rotating union"
would stand out quickly.

 

But
this experience can be avoided, if the machine manufacturer or the design
engineer focuses on quality from the outset when developing the printing
machines and if the user itself, e.g. as foreman, further pursues this focus
during operation.

 

In
the long run, cutting-edge technology pays off!

 

For more information contact NORMAN.G.
CLARK on (03) 9450 8200 or visit our
website at www.ngclark.com.au