Abstract: A device is provided for successively melting a solid working material, such as a hot melt adhesive, packed in a packaging bag, and for pressing the molten working material out of the packaging bag. The device includes a cylindrical receiving chamber provided with at least one outlet opening at the end for receiving the packaging bag filled with the working material and having a front end and a back end. At least one heating element (30) is positioned in the region of the at least one outlet opening for melting the working material at the front-end of the packaging bag, which has a discharge opening for the molten working material. A pressing device with a pressing plunger can be displaced within the receiving chamber and acts on the back end of the packaging bag.

Abstract: A piston wiper plate for a pressing unit for melting systems for bags includes a single-piece wiper plate having an axial upper side and an axial bottom side made of elastically resilient material, and a radially outer wiper edge that surrounds the periphery in the relaxed state. The sealing and sliding properties thereof remain within a predetermined range even when the temperatures fluctuate more drastically in that in the wiper plate includes at least one recess that is inserted in the axial upper side and/or in the axial bottom side and/or between the axial upper and bottom sides thereof and that allows for at least a radial compression of the wiper plate. At least one expandable restoring element can be inserted into the recess.