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Heraeus Infra-Red Can Cure


Published: 11/09/2013

by Heraeus Noblelight


A carbon medium wave infra-red system from Heraeus Noblelight, of Bromborough, is helping Carnaud Metal Box Ltd to cure lacquer applied to the longitudinal seam welds of cans at production line speeds.

The Bootle factory of Carnaud Metal Box manufactures a wide range of metal cans for containing industrial oils and greases. These are produced on high speed machinery, where the metal plate is bent, formed, cut to length and lacquered for protection before being longitudinally seam welded. The application of the lacquer coating to cans is an important part of the production process but this cannot be carried out along the line of plate to be seam welded before the actual welding takes place, as this would cause fusion problems. Consequently, lacquer must be applied along the length of the welded seam after welding.

The curing of the solvent-based lacquer applied to the welded seam must be carried out as quickly as possibly, if bottlenecks in production are to be avoided. Previously a radio frequency drying system had been installed and, although this provided the necessary drying rate, at speeds of around 100 cans/minute, it proved expensive to operate, was unreliable and inconsistent in performance, required frequent maintenance and was recognised as a health hazard.

To remedy this situation, Steve Jennings, the engineering development manager at Carnaud Metal Box, explored alternative drying technologies and decided to investigate the potential of infra-red drying for this application. As a result, following trials at Heraeus’s Bromborough Test Centre, a full-scale carbon, medium wave infra- red system was installed at the Bootle factory.

This consists of two, 16kW medium wave cassettes, which are located directly above the can conveyor line, immediately after the point in the line where the lacquer is applied to the completed seam weld. The arrangement is such that the infra-red output from the emitters is focused directly on the seam weld, to ensure efficient and rapid curing of the protective lacquer finish.

The infra-red system has proved more than capable of matching the production line speeds and the ability of the carbon emitters to be switched on and off very quickly has added to the overall energy-efficiency of the system. Furthermore, the system’s compactness has allowed considerable space saving over the previous curing techniques and the simplicity of design has reduced maintenance requirements to a minimum.