Moulds (or molds) and dies are used to make a variety of objects with many different media. For instance, plastic plumbing pipes can me made in a mould; tools such as wrenches are cast in dies. Moulds tend to be used to produce products that need to be hollow in the middle, whereas dies are used to stamp solid products out of media such as steel.
Moulds help manufacture things like doorknobs. There are two halves to a mould; this allows a great deal of detail to go into the center of the mould. A liquid medium is poured or injected into a premade mould; once the liquid is injected or poured in, it is allowed to cool and the mould is removed. The end result is a single component that may in itself be the end product, or it can be made to have other things attached to it.
Solid moulds are used to shape pieces of media.The medium is heated and formed into whatever shape the mould is. For instance, makeup artists may use a sheet of plastic and a mould to give added dimension to an actor's costume; this is especially useful if they are making something that does not exist in real life. If they need to make an actor a mask, for example, they would design the mould, put in a piece of flat plastic, and then press the plastic into place around the mould. This process takes a lot of pressure that has to be carefully monitored to keep the plastic from getting too thin or too hot.
Dies are used to cut objects from media; a cookie cutter is a very simple form of a die. Dies are useful because they can cut many objects at once, increasing productivity. Fancy edged papers are cut by dies, as are machine parts such as washers. Street signs are also cut with dies. The main idea behind dies is that they are used to create other shapes, and two dies can be used at the same time to create complex shapes.
Tools and toys are often made with the die casting process. Molten metal is poured or injected into dies and allowed to cool. The die is then removed, and the product is ready for finishing. Die casting is a relatively fast process, which allows for faster production. It is not as refined as the moulding process, and die cast objecys may not be as strong as products made with an injected mould.