the disclosure relates to a process and device for the production of moldings from foamed thermoplastic plastic , e . g ., polystyrol , in a mold , the mold wall enclosing a mold cavity , into which a filling injector discharges , and which is surrounded by an agent chamber and in which there runs an agent channel which is formed by drillings which are sealed at their ends against the outside and the agent chest by means of seals , and are connected to the mold cavity through nozzles . the drillings of the agent channel preferably run in ribs of the mold wall . the agent chest and the agent channel are connected through time - overlapping - controlled valves to an agent supply and removal system for the heating , cooling , inflation , curing , ejection of the mold walls and the molding respectively . a fast cycle sequence is achieved with a small consumption of energy and a high molding quality .