Injection molding is a fast, automated, versatile process that can produce precise, complex three–dimensional parts from a fraction of a gram to more than a hundred kilograms, in virtually any plastic material. The process starts with feeding small plastic beads into a heated screw and barrel system that melts the plastic into a high–viscosity liquid. The screw then forces the molten plastic into a closed mold that provides the shape, cooling and solidification, and finally ejects the part.
Injection molding is fast and can be economical. But because every part needs its own costly injection molding tool, the process is economically viable only for mass production, usually more than 10,000 parts. Injection molding tools take weeks or months to build. Often, design mistakes become apparent, requiring time–consuming mold corrections. Multiple iterations may go from the producer to the tool builder until the final part design and quality are achieved, increasing costs and product time to market.