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. Rotating unions are available from Norman G Clark .
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.
The ‘rotating union’ is important for this task. As the rotating union guides the medium into and/or out of the rotating part, its technology and degree of development affect the efficiency of the entire machine in the following ways:
- Primarily by way of optimised 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 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.
Chaff is separated from wheat (branded product) quickly. 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.
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 to use highly wear-resistant material combinations for mechanical seals. 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 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.