Abstract: A method for manufacturing a zipper without shift in injection molding comprises the steps of forming a bank of continuous zipper teeth at an edge of each of two parallel zipper strips by molding injection; wherein an inner side of each zipper strip has a respective connecting strip; scraping a part of zipper teeth on the zipper strip; melting two layers of films and coating the films on the upper and lower sides of the zipper strip; punching holes at inner lateral sides of the films, but the connecting strips are remained; guiding two zipper strips into an upper and a lower engaging piece molds; and tensioning the zipper strips within the molds; injection-molding engaging pieces; moving the molds from the zipper strips; cutting the zipper strips along the holes, thus forming the upper and lower engaging pieces of a zipper.

Abstract: A method for manufacturing a zipper without shift in injection molding comprises the steps of forming a bank of continuous zipper teeth at an edge a zipper strip; scraping a part of zipper teeth on the zipper strip; melting two layers of films and coating the films on the upper and lower sides of the zipper strip; punching holes at an inner lateral sides of the films; guiding two zipper strips into an upper and a lower engaging piece molds; and expanding the zipper strips; injection-molding engaging pieces; moving the molds from the zipper strips; cutting the zipper strips along the holes, thus forming the upper and lower engaging pieces of a zipper. When forming the hole, a connecting strip at an edge having the films must be retained. Thereby, the zipper strips can be precisely positioned in the upper engaging piece mold and the lower engaging piece mold.