A carbon infrared system from Heraeus Noblelight has proven successful in curing a lacquer applied to the longitudinal weld of metal containers at the AintreeHeraeus Crown manufacturing plant of Crown Packaging in the United Kingdom.

The system was developed when the existing foil heating system was unable to meet the curing requirements of a new lacquer formulation. Additional benefits include a reduction in line downtime due to decreased maintenance.

The Aintree plant manufactures containers for finished products ranging from industrial oils to foodstuffs. After being cut and formed from sheet material, the cans are longitudinally welded. The weld then is internally coated with a lacquer that prevents contamination of any food products and protects the weld from attack from aggressive contents. The lacquer is applied by spray and cured.

Previous curing solutions have included radio frequency ovens and infrared foil heaters. When the lacquer formulation was upgraded, neither of these heating systems could achieve the correct cure. Looking for a solution, Heraeus carried out proving tests with carbon infrared at its application center in Neston, Cheshire. These proved so successful that a small-scale test unit was supplied to Crown for on-site trials, which led to an 84 kW carbon infrared (CIR) system being installed.

 The system consists of three 28 kW carbon infrared modules, each fitted with two 14 kW carbon infrared emitters. The infrared heat is applied from the outside of the container, and the heat is conducted through the weld to cure the lacquer on the can inside. Each module’s output can be independently, manually regulated so that heating profiles can be matched to specific can sizes. Alternatively, the line speed can be varied to change the can dwell time under the heaters.