In the traditional approach to product development, there is a sharp line between development and production. Development begins with a light bulb over someone’s head, proceeds through napkin sketches and CAD models, and ends, ultimately, with prototypes. At one or more points in the development process there may be input from the market, be it someone’s best guesses, one or more focus groups, or actual market tests. And from start to finish there is always pressure to “get on with it,” either because you need to catch up with a market leader or because you are the leader and someone may be catching up with you. But then, when you have reached your goal—a fully developed, marketable product—everything comes to a screeching halt and the drawings and/or models disappear into the “production machine,” from which, weeks or months later, a whole lot of deliverable product appears and the rush begins again as it heads off to market.
In plastic moulding, as in most other technologies, some aspects of this transition are unavoidable. Production moulds are costly, and they take time to manufacture. It would be risky to begin producing them before the design had been fully proven in development, when even a small change could turn tens of thousands of dollars’ worth of moulds into doorstops and boat anchors.
Traditionally this has always presented manufacturers with a dilemma. They could keep development and manufacturing sequential and live with the resulting delay. Or they could treat them in parallel, starting on production moulds before the end of development, cutting their time to market but running the risk of having to go back and start tool-making over again. It was a painful choice, because today’s competitive global markets reward both speed and low cost. Manufacturers already recognise that rapid injection moulding as a prototyping method can reduce both cost and delay in the design of plastic parts. They are now beginning to see that it can also help reduce the post-development delay in bringing a product to market.
Bridge Tooling
While rapid injection moulding is not identical to traditional production tooling, it is similar enough in process and technology to solve several problems and help speed up production. First, in addition to proving the design itself, it confirms that a part can actually be moulded. Second, while production-tool moulding can incorporate capabilities that rapid injection moulding can’t—internal cooling lines or sophisticated venting, for example—adapting a part to the demands of rapid injection moulding by equalizing wall thicknesses and maintaining draft can actually simplify and speed up the manufacture of production moulds while reducing their cost. In other words, rapid injection moulding doesn’t just produce prototype parts; it prototypes the production method that will produce those parts, allowing avoidable problems to be eliminated before the start of final mould making.
Perhaps even more important in today’s fast-moving markets, tools made for rapid injection moulding can also be used to mould parts in actual production resins and in production volumes—thousand or even tens of thousands of parts—while the “official” production tools are being made. In other words, yesterday’s prototyping moulds can produce today’s “go-to-market” parts while tomorrow’s ultra-high-volume moulds are being made.
