Cut to the quick

A UK university collaboration is testing two high-speed lasers claimed to offer better beam quality and power density over existing systems. Christopher Sell reports.

Two high-powered lasers, one of which was originally intended for use as a weapon, may soon make their debut on the factory floor for high-speed precision manufacturing applications thanks to collaborative research being led by the University of Manchester.

The first of the state-of-the-art lasers, hitherto untested in a traditional manufacturing operation, is a 1kW fibre laser originally developed by NASA and the MoD for a direct energy weapon programme. According to team leader Prof Lin Li it offers greatly improved beam quality and power density over existing systems, and will enable researchers to cut deeper and faster.

A second system, a 400Whigh-powered diode pumped solid state (DPSS) laser, is also being evaluated. Li said that this is the world’s highest power pulse laser and can cut with extremely high precision. It was originally developed for the generation of deep UV light sources for advanced lithography systems.

Once installed, the team will work alongside project partners from Cambridge, Cranfield, Heriot Watt and Nottingham universities. ‘Basically it is a combined effort among four or five universities to push UK technology in laser precision manufacturing,’ said Li.

He pointed out other potential advantages. ‘Most lasers cut using a continuous beam or pulsed beam at millisecond pulses. But DPSS has nano-second pulses, and therefore allows us to cut materials more precisely.’ Such a high power pulse, which peaks at 1GW/sq cm, is sufficient to vaporise any material that has been removed instantly, providing more precise cutting.

‘If the laser pulse is short, the amount of energy conducted to other parts of the material will be limited. Thus the energy can be better used to vaporise the material. This laser has the advantage over femtosecond models (normally 1W) in that the average power is high (400W) therefore the removal rate is highly suitable for practical production work,’ said Li.

Once the lasers are installed, the team will begin investigating their use for high-speed cutting and high-precision cutting, which, according to Li is impossible to with current lasers due to inadequate speed and accuracy. To overcome this, Li is planning to develop a high-speed linear motor system so that the work pieces can be moved very fast.

Additionally, a new gas system will have to be developed, as the laser merely melts the metal while a strong gas jet actually cuts through. Other potential applications include the machining of materials such as carbon alloys, ceramics and diamonds; there is even some interest from within the nuclear industry. BNFL, for instance, is looking into using the laser for decontamination and decommissioning.

Li said the research taking place in Manchester — with the aid of an EPSRC grant of almost £600,000 — is designed to tackle the next generation of manufacturing challenges, namely size and the constant move towards smaller parts.

It is hoped these new lasers should be able address them. ‘All the laser work is preparing for advances in manufacturing,’ said Li. ‘They are a much smaller size, more compact and better quality, higher power. They have advantages other lasers do not have.’