part molding tool 1 consisting of an upper part 2 and a lower part 3 the molded article 5 which is to be coated is placed in the mold cavity 4 of the molding tool 1 for the illustrative embodiment shown in fig1 the molded article 5 is a circular aluminum profiled disk of which the outer rim 6 must be coated with a rubber seal the rubber material will be injected into the mold cavity 4 after the molding tool 1 has been finally closed to prevent the rubber molding substance injected into the mold cavity 4 from penetrating the separation plane gap 7 between the lower side of the upper tool 2 and the upper side of the molded article 5 and the separation plane gap 8 between the upper side of the lower tool 3 and the underside of the molded article 5 edge sealing profiles here cutting edge profiles 9 and 10 circular and closed on themselves integral with the upper tool 2 and the lower tool 2 respectively are provided at the outer rims of the surfaces on the molded article 5 which must be kept free from the rubber material for the sake of clarity these cutting edge sealing profiles 9 10 are shown exaggeratedly in fig1 the tool 1 is shown in the phase directly before final closure the moment the final closure force presses the two tool parts 2 3 against each other whereby these lie flush against one another by their surfaces 11 12 the cutting edge profiles 9 10 dent the surfaces of the molded article 5 and thereby seal the mold cavity 4 hermetically against the separation plane gaps 7 8 the touching separation plane surfaces 11 12.