Any manufacturer trying to confidently stick two pieces of polypropylene type materials together is usually faced with using environmentally unfriendly pre-treatments. Some of these pre-treatments are chemical, others heat based, but all waste time and cost money. These can now be dispensed with thanks to a set of novel laser bonding techniques developed by the Warwick Manufacturing Group at the University of Warwick.

Researcher Tony Hoult wished to improve on current techniques for difficult to bond plastics. Industry currently uses processes requiring the application of heat or time wasting and environmentally unfriendly solvents. Many researchers are investigating how lasers could perhaps be used instead to pre-treat and weld plastics but they are using complex expensive lasers. Their laser based plastic welding techniques also require at least one of the plastic components to be transparent to allow the bonding laser light to pass through it to the interface between the two components.

Tony Hoult has devised a very different approach that goes against conventional thinking on the use of lasers to solve plastic bonding problems. To pursue these techniques he has obtained a revolutionary compact, very high powered (1.2 kw) diode laser made by Rofin Sinar Ltd. This is the first of its type in the UK, and is several hundred thousand times more powerful than well known laser pointers. Its laser head is only about the size of a car vacuum. Its small size allows it to be directly mounted on small inexpensive assembly line robots.

By close study of the behaviour of the laser beam combined with research into the joining properties of many plastics he has devised unconventional but extremely effective techniques that can:-

• Bond plastics and reinforced engineering plastics without disfiguring pre-treatment