Cool-cure technology for metal decorating presses

UV Feature – CanMaker – January 2010

GEW has further developed its NUVAPlus system for curing UV inks and coatings on metal decorating presses as a result of a joint design and engineering program with customers.

With the objective of optimising press performance GEW re-assessed the technical issues associated with UV curing in the metal decorating process and the need for precise heat management as well as reduced energy consumption. The NUVAPlus system addresses these issues and comprises curing modules with the company’s Cool-Cure technology, electronic power supplies and programmable control system.

Excessive heat during the UV curing process can result in print register problems, substrate warping, dimensional change, loss of temper and damage to the conveyor, press frame and drives.  Materials used in the metal decorating process include steel, galvanized steel, tinplate, aluminium and copper. Each varies in terms of heat absorbance and reflectivity, heightening the need for precise heat management which is achieved through GEW’s Cool-Cure technology.

The NUVAplus inter-deck curing units have been designed to be mounted over the conveyer belt section at press in-feed to obtain surface cure between print units.  These are combined with a single-lamp under-sheet curing unit mounted between the conveyers. A final set-stack of multiple UV lamps is mounted over the belt section of the press to avoid the potential of the sheets bonding together through incomplete cure.

All UV curing units include an air-cooled heat sink to avoid overheating of the substrate and conveyor components. The UV lamp heads can be elevated for maintenance and are held in the raised position through gas struts for operator safety and damage prevention. A cassette system enables quick and easy removal of the complete assembly of working parts inside the dryer to permit ease of access for maintenance of the UV system itself.

NUVAplus includes a 32kW power supply that provides 30% increased power conversion efficiency over transformer power supplies with UV output increased by up to 20%.  The stand-by power is typically halved during machine stoppage to further reduce energy consumption. Lamp output and curing are stable and unaffected by mains input irregularities.  Step-less power adjustment provides optimum curing performance and temperature control.

A programmable control system for operator interface and UV monitoring completes the installation.  The system comprises a touch-sensitive colour display with intuitive icon-based menus for ease of use and a clear display of the system status of all control parameters with multi-lingual capability.