The electrical function refers to the plugs ability to properly conduct current from the socket to the electrical device in a safe and proper manner. The mechanical function refers to the sockets ability to withstand all the forces required for safe installation of the plug into the socket. The mechanical function also includes the proper design of the plug so as to safely clip into the socket and be safely held and removed from the socket. Aesthetic function refers to the ability of the socket to have appealing features to the customer. Ergonomic function refers to the sockets ability to withstand fatigue due to continual use.2
The 13A pin is made of the following components. Conductors are the three pins; they are made of brass. Fuse element made of copper. Fuse clip made of copper, cable wires made of copper and fuse ends made of copper. The insulators are the plug body and base made of plastic. The cord clip made of nylon, Cable sheath made of PVC (polyvinylchloride) wire sheath and pin sheath made of PVC. Fuse body made of alumina. The pin has screws firmly holding together all the parts. The cord grip screw is made of steel, the major plug screw is made of steel and the pin screw is made of steel or brass.3
In the process of material selection, the engineer should consider the materials are the best conductors and those that are the best insulators. The engineer should consider the price and the ease of molding and access the materials. Polymers can be shaped into the desired shape of the plug through molding. This can be easily done for mass production. Wood can only be machined; this method is ineffective for mass production. Thermoplastics have various options for mass production such as welding, use of adhesives and molding. Therefore, even though wood provides the cheapest source of raw materials, it is difficult to use it in mass production.
The plug body should be strong and stiff so as to hold the pins safely. Through a material selection process an engineer is able to select the most suitable polymer to use.