Channels and pockets must be accurately machined. The specification of correct tolerances is also critical. Costly errors Mould tools are built almost exclusively from standard components, ordered from specialist suppliers whose catalogues contain tens of thousands of items. As they choose each component, draughtsmen must also add its part number to the list of materials to be ordered, either by referring to the supplier's catalogue or, as very often happens, relying on memory. Some component suppliers provide CAD definitions of their parts, but selection still depends upon the expertise of the individual designer, and the process remains laborious, requiring extensive user input and manual positioning of the new part.
Most draughtsmen find it quicker to draw each part from scratch.
The complete design process for a large and complex mould tool may take as long as a year, and errors are frequent and costly. Each 'misremembered' or mistyped part number means a costly delay while the correct part is ordered. Worse, incorrect positioning on the plan of a hole in the mould plate may not become apparent until the tool has been assembled. Too expensive to discard, the plate must be removed, welded, redrilled and refitted. It will also dramatically reduce the incidence of the costly ordering and manufacturing errors so often generated by traditional design methods.