Making ships with lasers

The first commercial use of BOC’s LASOX process has taken place at the Bender Shipbuilding yard in Alabama in the US where a laser made a series of cuts through steel plate using less than 2kW of power.

The first commercial use of the LASOX process has taken place at the Bender Shipbuilding yard in Alabama in the US where a laser made a series of cuts through steel plate using less than 2kW of power.

The LASOX process is the result of eight years research between BOC’s UK-based Fabrication Technology Centre in Wolverhampton and Dr. Bill O’Neill of Liverpool University.

Combining the benefits of laser and oxy- fuel cutting, LASOX uses a laser beam to provide a pre-heating condition so that the surface area illuminated by the laser beam reaches the ignition temperature of steel at approximately 1000 degrees C.

To achieve this, a modest amount of laser energy is required, about 1kW, so the process can be operated with relatively small low cost lasers. This laser beam in effect replaces the fuel gas in oxy-fuel cutting. This defocused beam is then combined with a high-pressure supersonic oxygen gas jet, which provides the cutting energy.

Although laser technology has had a massive effect on sheet metal cutting, it has made little or no impact on plate cutting as the process thickness limitation has been found to be about 25mm in C-Mn steel plate. Thicker material has traditionally been cut with oxy-fuel and more recently with plasma torches but both processes suffer from quality issues.

Dr. Jack Gabzdyl, BOC’s market development manager, said: ‘The LASOX process was originally envisaged as providing a thickness capability extension for the laser cutting process. However, based on the initial success of the trial and with further refinement, the LASOX process could become a modern alternative to traditional thick section profile cutting methods such as oxy-fuel.’

Pat Cahill, research and development manager for Bender Shipbuilding, said: ‘A year ago, cutting steel thicker than 50mm would have been unheard of with a 2kW laser – 25mm being the maximum cutting depth undertaken commercially.’

‘This process has the potential to cut steel plates as thick as 100mm. Currently high-powered plasma cutting is limited to 75mm. This development opens up the possibility of a new generation of steel ships that are stronger and cheaper to build.’

The successful trial at Bender Shipbuilding is part of a national shipbuilding research programme (NSRP) project in the US, which provided more than £300,000 to support the project. Led by Bender Shipbuilding, a consortium was formed consisting of Alabama Laser Systems, Bender Shipbuilding, Caterpillar, General Dynamics – Electric Boat and BOC. As well as hosting the trial, Bender Shipbuilding organised the project team, obtained funding through the NSRP and provided end user guidance for the LASOX application.

BOC provided the basic technology and process license for LASOX. Alabama Laser Systems carried out the commercialisation of the process and the integration into the existing laser cutting system at Bender. After a year of evaluation and development, the system is now in full production at Bender Shipbuilding.

The installation at Bender has been so successful that the programme is being brought forward by three months and in early 2003 full installations at Caterpillar, for their heavy duty mining equipment, and General Dynamics – Electric Boat, for use in the building of submarines, are expected.