When plastics were first gaining popularity, parts were simple. Most products were designed on a drawing board, so it was natural that the tooling was designed that way as well.

All that was needed was a drawing board, a box of pens, a ruler, compasses, and a razor blade for when things went wrong or the design changed. Of course, the tool designer also needed a high degree of skill, and considerable patience for doing repetitive actions, such as drawing ejector pin holes.

The introduction of 2-D CAD systems in the 1970s improved mold design in two key ways: (1) routine, repetitive tasks were massively simplified by the ability to copy geometry from one area of the drawing to another. This was made even easier by the introduction of symbols, allowing complicated sub-assemblies to be stored in a library and added to the drawing at the click of a mouse; and, (2) making modifications to a design also was simplified, as areas of the drawing could be deleted, moved, re-trimmed or stretched to accommodate the change. But still the biggest issue was successfully and completely defining a complex 3-D form using 2-D drawings.

As CAD has evolved into 3-D the complexity of plastic molded parts has increased. Modern plastic products seek to be increasingly creative in terms of form, while being more functional and durable. For the mold designer, these new forms have forced a requirement for CAD systems to be able to accurately reproduce complex shapes, not just for the visible parts of the product, but especially for the functional parts of the mold, such as parting surfaces.

While the modern generation of CAD systems can cope with this increased complexity, much of the mold designer’s work is still routine and mundane. Consider placing a series of ejector pins into a mold cavity block. Each pin must be placed individually, complete with its corresponding clearance hole and then trimmed to length. Even allowing for the fact that computers can do this type of operation very efficiently, the mold designer will still be spending too much time and effort on tedious tasks, and not enough on making sure the design is perfect.