The modern-day injection mould tool is often a complex arrangement of mechanical, electrical, pneumatic and hydraulic components expected to fulfil a range of demanding tasks. Whatever the complexity, the mould design must essentially specify a tool that will operate satisfactorily in production. To achieve this it must meet the following prime objectives:

• It must operate at the required production rate or better and last at least for the predicted design life.

• It must be well designed and produce mouldings to the required specification.

• The design must specify a tool that will operate consistently and be reliable in production. It should not be prone to frequent breakdowns and should not require frequent maintenance or servicing.

These objectives are not simple to achieve. At every cycle, the tool is clamped together under high loads and is subject to high injection pressures and high heat levels from the incoming polymer. During the cooling cycle, the moulding is cooled until it reaches ejection temperature, when the tool opens and the moulding is ejected. All these factors combine to make the mould tool a highly stressed dynamic heat exchanger.

It is important, therefore, to ensure that the mould design takes all these factors into consideration. Additionally, there are several other requirements that need to be considered, among which are the following:

• The number of impressions required

• The type of tool needed, e.g., two-plate, side core, split, multiplate, hot runner and so on

• The mould materials

• The cavity construction

• The required life of the tool

• Temperature...