What is a Child product mould? It is a device that is used to give a plastics material shape. It may be hollow， in which case it is said to be a negative mould ; or it may be convex (hump-shaped), in which case it is called a positive mould . The plastics Child product made in or on a mould is called a moulding. The surface of the moulding is usually a mirror image of the mould, —that is, the opposite way round. The designer of a plastics product has to think about the positive and negative shapes of both the mould and the moulding at the same time.
In some processes it is possible to use a simple mould, which can be either positive or negative, the choice being made on the basis of which surface is most important in the finished product. There are, however, several processes where the mould is in two halves, one positive, the other negative. One fits inside the other, leaving a space called a cavity, which is filled with plastics material. The plastics material is forced into the cavity, hardens into a solid, is removed and has good surfaces on both sides. Injection moulding is a typical process of this type, and is a method of pressure casting. Often it is impractical to modify a mould and it is unusual for mouldings to be altered once they have been formed.
In some processes a mould can be referred to as a plug, a former, a preformer、a jig or a tool. In industry a simple mould can cost as little as a few hundred pounds; a complex one can cost many thousands of pounds. A small part of the cost of a mould is paid for each time someone buys a moulding. Usually thousands of mould¬ings are made from a mould.