Plastic bottle cap molds are specially designed to create different product shapes from plastic resins or thermoplastics. Most of these molded caps come with anti-tarnish properties and high resistance to ultraviolet light. They can also be used for cosmetic products such as mouth guards, facial tissues, hair bands and waterproof caps. It is important to note that plastic bottle cap molds must be well-tested and maintained according to the manufacturer's specifications in order to prolong their service life and increase their output quality.
Plastic bottle cap moulds are generally run by a high pressure hot runner. The hot runner heats the plastic resins, then forces them through a die that is built into a vertical rotating drum. As the plastic flows past the die, it feeds into a cooling chamber, where the molten plastic separates into different textures depending on the specific product being manufactured. Different textures will produce different sized and shaped products, and therefore, it is important to determine the ratio of thick to thinness when molding. After the plastic has cooled, the plastic cap mould is inverted and the molds are left to cool. When finished, they must be removed from the chamber in order to prevent overheating.
In order to illustrate a working principle of a demolding mechanism, an identical bottle cap mold is fabricated using a computer aided manufacturing system (CAM). A computer directs the CAM to duplicate the same product in a identical manner as if it were printed on a paper. In this embodiment, the CAM software receives two photographs, one showing the layout of the cap and one showing the final product. The user then chooses between two selections; "print" or "demold". The CAM software program merges the two images, producing a three dimensional replica of the cap. By using complementary colors and textures in the cap, it is possible to create an exact replica of the original item.
In order to demonstrate a practical application, a set of standard bottle caps is produced and laminated with an exterior coating. A rubberized fabric cover is then applied to the product. Next, the plastic mold is prepared by passing a wire mesh through the bottle cap mold so that the mold cavities are accessible. The laminated outer cover is then attached to the moving parts, such as the movable side surfaces of the cap.
The process is repeated several times until the desired results are achieved, typically within three to five passes. Once the caps are complete, it is necessary to remove them from the molds. One convenient technique for removing caps from molds involves using a pair of scissors and pushing the scissors deeply into the cavities, allowing the caps to slip out. In another approach, the cutter may be pushed down deep inside the mold so that the molds contents pop out.
A variety of plastic caps and sealing techniques are available to achieve the desired result. However, high precision accuracy is required when shaping or sealing bottles with this equipment. For this reason, most mold makers rely on high precision industrial machinery.