Efficient welding
The secret to PLT's Laser Plasmotron is that a portion of the laser energy propagating through the plasma is absorbed and coupled into the plasma arc before it reaches the work surface. Company officials say the collinear laser-plasma arc welding head produces several beneficial effects: increased plasma temperature and electroconductivity along the laser axis; a constriction of the plasma arc and a resultant increase in the plasma energy density; greater dynamic pressure at the weld; and increased rigidity of the arc.
Also, because the plasma head nozzle constricts the gases, a relatively small part of the laser beam power is lost to the plasma during transmission. These combined effects cause the arc to become more like a laser than an arc, according to company officials.
PLT has developed two heads that combine a plasma arc with either a CO2 or an Nd:YAG laser. Tests show that a 1-kW Nd:YAG laser with focal spot diameter of 0.67 mm, collinearly combined with a plasma arc, achieved the equivalent welding performance of a 2-kW stand-alone laser. This increases the life of arc electrodes while reducing consumption of welding gas and electrical energy. Also, welded joints are clean, a condition usually obtained with laser-only welding systems.
Potential commercial applications include the automotive, shipbuilding, aerospace and offshore sectors. The device was developed with an industrial R&D grant from Israel's Ministry of Industry and Trade.