Overmolding is an injection molding process that creates parts from two or more materials. It is sometimes referred to as ldquo;in-mold assembly.rdquo; Overmolding can be roughly divided into two distinct processes, insert molding and multiple-shot molding. Insert molding (sometimes spelled insert moulding) is commonly used to add metal features to plastic parts such as threaded bosses, but it also describes the technique of coating any preformed object with plastic via injection molding. Multiple-shot molding is used to create plastic parts from multiple materials, such as polypropylene and silicone rubber,during a single molding process to improve external characteristics such as impact resistance and feel. This article looks at both kinds of processes and discusses applications where one process might be selected over the other.