TechArchive

This article was originally written in the period 1995-2000

Alan Griffiths is a design consultant to the plastics industry. He offers his personal and thought-provoking views on rapid prototyping.

At the moment it does not seem to matter which engineering journal one reads, the headline “Rapid Prototyping” so often stands out. The expression seems to have crept insidiously into the designer’s vocabulary.

The problem is the constant use of the word “rapid”. Maybe next year, the buzz word will be “rapid, rapid prototyping” and then again at the turn of the century will it be “rapid, rapid, rapid prototyping”?

Prototyping – modelmaking – has always been a part of development engineers’ armoury and they have always had to choose between one of many prototyping routes. In the 1950s and 1960s, prototyping was often achieved by taking an existing product and cannibalising it, in order to produce the Mk II or Mk III versions of the original product. The approach often resulted in aesthetically sub-standard products, but on the other hand, it frequently ensured that the best elements of a product design were carried forward.

Undoubtedly, the expression “rapid prototyping” is now frequently used, due to the wider use of 2D and 3D computer aided design. The use of CAD-generated information has now made it possible to generate prototypes without using the traditional modelmaking process.

But examining the various stages of product development shows that the time allocated to build prototypes occupies a relatively short period of the total development programme. Todays marketeers, sales managers and managing directors, now aware of the expression “rapid prototyping”, are more likely to procrastinate just a little longer before making decisions, hoping to catch up by “rapid prototyping”! But if they understood that a “normal” prototype took four weeks to produce, as opposed to a CAD-assisted model taking two weeks, they would be obliged to make their decision to “press the button” just two weeks earlier in order to meet the same eventual target dates.

Please don’t think that I do not fully appreciate the advantages of the latest CAD-aided prototyping manufacturing methods. In fact, it is likely that before the end of this century we will see more user-friendly CAD stations operated by proficient young designers and that, as they draw on their screens, a model will be produced simultaneously. Unless virtual reality takes over thus bypasses the prototyping stages completely!

However, there are alternative ways of hurrying along projects before prototypes are produced. One way is to convert computer-generated designs into photo-realistic renderings, such as the illustrations shown here produced by Adrian Dodds Design Service. This is a relatively convenient method of producing three-dimensional coloured illustrations and presenting them in such a way that the ideas can be easily understod by sales and marketing people, who might otherwise have difficulty intepreting engineering drawings.

Such renderings can be rotated easily to illustrate alternative views and perspectives, while colours, shadings and backgrounds can be changed at the press of a button. The ability to carry out these adjustments with precision and speed gives photo-realistic renderings the edge over conventional freehand illustrations. A further advantage of this approach is that digital data can be utilised to produce video presentations which illustrate the product in service, prior to commissioning prototypes. Adrian Dodds supplies fully-edited videos of broadcast quality; they demonstrate the features and benefits of the product and and include title sequences and a professional voice-over.

In practice, this “digital-imagining” approach is of most benefit when the eventual end product is large, when the cost of abortive modelmaking could be prohibitive.

While the most high-tech methods of prototyping will continue to gain support and momentum, traditional modelmaking mathods should also be considered before computer-led solutions are used. There is till much to said for using highly skilled modelmakers to produce prototypes. One advantage of this approach is that the skilled modelmaker adds a human input to the product design. I know of one traditional modelmaking company which specialises in taking “failed” CAD information and swiftly building vacuum forming tools which can then produce prototype plastics automobile trim panels for the stylist’s approval. There will always be a need for competent designers to be trained to produce pencil and paper sketches for some of the more intricate design details before turning to their CAD station.

One of the lecturers at a recent seminar at the Victoria & Albert Museum was the highly respected industrial designer Paul Priestman, who has clients in the USA ad mouldmakers in the Far East. As expected, Paul appeared to be preoccupied by cost and speed and spoke of frequently burning the midnight oil in order to satisfy his clients’ needs. Understandably, his office now has no drawing boards and relies heavily on CAD stations, as well as rapid prototyping. He said that on some occasions, they send their latest “drawings” by modem to their clients in the USA and they, in turn, would modem the “drawings” to the toolmakers in Korea.

Thus the mouldmaking would be taking place to the designer’s notes before Paul returned to his the following day! The frightening thought is that eventually one may be able to call in electronically-friendly, globally-located partners, so that a product can be manufactured between the time the designer has supper and finishes breakfast. That would indeed be rapid!

• Alan Griffiths