The newly developed KTT foaming line for manufacturing insulated polyurethane door elements combines the advantages of a continuously operated circulation line with those of a stationary line. Disconnecting the operating line from the curing places enables improved operation of the line with varying curing times. The vertical arrangement of the curing places continues to permit a space-saving design of the line. The KTT system is divided into an operating and a curing section, and has an ergonomically optimized loading station as well as an automated foaming and removal station. In order to guarantee an optimum initial foam distribution of the door elements, two MT mixheads are used, which are guided by a multiaxial mixhead manipulator. The central element of the curing section forms a lifting/lowering gear, which transfers the foamed mold carriers into vertically arranged curing places. After the respective curing times, which may be different for each mold carrier, the mold carriers are supplied back to the operating section. The line also has a mold carrier changing station, which allows a mold carrier to be automatically moved in and out during operation.