Abstract: In a method of making separable sliding clasp fasteners, the interlocking elements of a thermoplastic material which are on the edge of a band of the fastener are placed in a mold such that thermoplastic material is injected into the mold and formed over a segment of the interlocking elements and allowed to solidify. By cutting the solidified material in the mold, the male parts of a separating device of the fastener are formed. A device for carrying out this process includes a mold comprising an upper half and a lower half. The lower half of the mold has on each side of its central axis, a longitudinal cavity and a band reinforcement track, adjacent to the cavity, and means for injecting molten thermoplastic material into the mold. Each of the cavities has a stationary part and a moveable part, with two lines of contact between the stationary and the movable parts, the purpose of which is to shape the two opposite lateral sides of the two male parts to be manufactured.