System cures weld lacquer

The plant manufactures containers for products ranging from industrial oils to foodstuffs. After being cut and formed from sheet material, cans are longitudinally welded. It is important that this weld is internally coated with a lacquer, to prevent contamination of food products and to protect the weld from attack from aggressive contents. Lacquer is applied by spray and must then be cured.

Crown contacted Heraeus, who carried out proving tests with carbon infrared. These proved successful and a small-scale test unit was supplied to Crown for on-site trials. An 84kW carbon infrared (CIR) system has subsequently been installed. It consists of three 28kW CIR modules, each fitted with two 14kW carbon infrared emitters. IR heat is applied from the outside of the container and 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.

"Apart from ensuring the correct lacquer cure, the new system has also brought other significant benefits,” says Paul Kavanagh, project engineer at Crown. "Unlike the previous foil system, which required considerable guarding to prevent unwarranted access, the new CIR modules are already totally sealed. In addition, we suffered considerable downtime when foils failed and had to be replaced. So far we have not had one CIR emitter failure.”