Ice blasting apparatus and trimming method for film insert molding

A trimming method for a film insert injection molding comprising the steps of:

• providing an injection mold having a cavity;
• inserting a soft film material into the cavity of the injection mold;
• closing the injection mold;
• injecting a molten resin into the cavity of the injection mold which defines a resin molding, wherein said soft film material and said resin molding define a film insert molding;
• removing the film insert molding from the injection mold, the film insert molding comprising a supported portion of the soft film material adhering integrally to a face of the resin molding, the film material further having an unsupported extending portion extending beyond an outer peripheral edge which extends about the entirety of the resin molding;
• providing an ice mixing tank storing an ice slurry, the ice mixing tank being connected to provide the ice slurry to a blast gun;
• aligning the blast gun with the outer peripheral edge of the resin molding;
• blasting a predetermined concentration of ice slurry from the blast gun towards a vicinity of the outer peripheral edge of the resin molding;
• and
• moving the blast gun sequentially along the outer peripheral edge of the resin molding in order to separate and remove the unsupported extending portion of the soft film material extending beyond the outer peripheral edge of the resin molding, wherein the outer peripheral edge of the resin molding supports and prevents damage to the supported portion of the film material during the blasting step, and the unsupported portion is separated from the supported portion along the peripheral edge by the blasting step.

A trimming method for a film insert injection molding comprising the steps of:

• removing from an injection mold a film insert molding comprising a soft film material having a supported portion adhering integrally to an underlying face of a resin molding, the soft film material having an unsupported portion extending beyond a peripheral edge of the resin molding,
• aligning a blast gun with the peripheral edge of the resin molding wherein the blast gun is disposed above and faces toward an exposed surface of the film material;
• blasting a predetermined concentration of ice slurry from the blast gun towards a vicinity of the peripheral edge of the molding wherein the ice slurry strikes the exposed face of the film material transverse to the exposed face and the underlying face of the resin material;
• and
• moving the blast gun sequentially along the outer peripheral edge of the resin molding in order to separate and remove the entire portion of the film material extending beyond the outer peripheral edge of the resin molding, wherein said resin molding supports said film material along the peripheral edge and said unsupported portion of the film material is separated from the supported portion along the length of the peripheral edge by the blasting of the ice slurry against the unsupported portion.