Manufacturing method of a snap fastener

Manufacturing method of a snap fastener with tape for integrally molding a male button made of synthetic resin on front and back faces of tape such that the male button holds a peripheral edge of an attachment hole of the tape having at least one attachment hole, comprising the steps of:

• fixing the tape with the attachment hole in position between cavities of a fixed mold and a movable mold;
• closing the movable mold against the fixed mold and clamping a tape portion of the peripheral edge of the attachment hole by at least a pair of clamping members projecting to face each other in the cavities of the molds;
• forming an introducing passage for introducing molten resin through a center portion of the attachment hole of the tape and at least one molten resin guide passage for supplying the molten resin linearly from the introducing passage as a center toward the peripheral edge of the attachment hole;
• forming an opening of the introducing passage to directly open into a cavity face opposite to a cavity face for molding the engaging potion;
• forming in the same opposite cavity face at least one or more molten resin guide passages having at least one wedge-shaped recessed groove with an end communicating with the opening of the introducing passage and a tip end thereof directed to the peripheral edge of the attachment hole of the tape;
• forming the opening of the introducing passage near a plane including the attachment hole of the tape;
• injecting the molten resin into the cavity through the molten resin guide passage toward the peripheral edge of the attachment hole of the tape;
• and
• fracturing and removing a molded potion of the introducing passage,
• wherein the male member comprises the male button which is in a substantially T-shape in section, and has an engaging portion to be engaged with a female button at a center portion of the male button, and which is molded integrally with the tape.