300 words
16 April 2004
The Engineer
English
Copyright Centaur Communications Limited or its licensors 2004

I read with interest the article 'Let there be light' (Design Engineering, 2 April) in which you discussed the potential of a new laser-based manufacturing future that will lead to the replacement of conventional 'Victorian' manufacturing methods.

Alan Jocelyn's vision of replacing conventional principles with laser- based fabrication using cutting, welding, machining, forming and joining techniques is, to say the least, ambitious.

Lasers can cut and weld with considerable finesse, but their abilities to form and machine are limited by the nature of their interaction with materials. Laser machining, although an attractive proposition, has received little attention over the past 40 years.

The generation of laser-induced melt is the limiting effect; melt flow brings with it inherent inaccuracies and deleterious material properties such as re-cast layers that possess troublesome microstructures - structures that the aerospace industry would refuse to fly.

The answer, of course, is to machine without melting such as the techniques applied by ultrafast laser jockeys. Unfortunately these systems are good for micro-parts, but macro-parts must wait for massive increases in power output perhaps realisable from the third, fourth or even fifth generation of ultrafast lasers.

Mr Jocelyn's vision is still rather Victorian in nature since it relies on techniques that cut, weld, machine and so on. Here at Cambridge the future vision of manufacturing is based on time compression technologies, which are flexible, reconfigurable and carry no tool, jig or fixture penalties - especially rapid manufacturing technologies that are evolving from rapid prototyping principles of the 1990s.

In 20 years' time, titanium and other components will be grown in a complete form, thereby relinquishing the need to cut, weld, bend or join; principles which are, of course, distinctly Victorian.

Dr Bill O'Neill Institute for Manufacturing University of Cambridge