Injection moulding is one of the most important methods of manufacturing
plastics products. Through the development of sophisticated micro-
processor control systems, the modern injection moulding machine is
capable of producing precision mouldings with close tolerances in large
numbers and with excellent reproducibility. This capability, however, is
often limited by the lack of a proper appreciation of mould design. The
mould, or tool as it is often called, is at the heart of the injection
moulding process. Its basic function is to accept the plastic melt from
the injection unit and cool it to the desired shape prior to ejection.
It is not, however, simply a matter of the mould having an impression of
the shape to be moulded. Many other factors have to be taken into
account - for example, the ability to fill the mould impression properly
and efficiently without inducing weaknesses in the moulding and the
efficient cooling of the moulding in order to maximise production rates
without diminishing the quality of the moulding. In addition, the type
of mould, gate and runner system, and ejection system which will best
meet the needs of a particular job specification have to be determined.
In our experience lack of attention to such factors leads to the mould
limiting the ability of the injection moulding machine and preventing
the process as a whole from achieving its true potential.