stationary whilst the workpiece is fed through, and rotated around its longitudinal axis. There are some configurations where, as with 3-dimensional plasma cutting, the cutting head can tilt and rotate. This allows angled cuts to be made through the thickness of the tube or section, commonly taken advantage of in the fabrication of process pipework where cut pipe can be provided with a weld preparation in place of a straight edge. New technology In the past decade plasma torch manufacturers have engineered new models with a smaller nozzle and a thinner plasma arc. This allows near-laser precision on plasma cut edges. Several manufacturers have combined precision CNC control with these torches to allow fabricators to produce parts that require little or no finishing. The transistors used were initially MOSFETs, but are now increasingly using IGBTs. With paralleled MOSFETs, if one of the transistors activates prematurely it can lead to a cascading failure of one quarter of the inverter. A later invention, IGBTs, are not as subject to this failure mode. IGBTs can be generally found in high current machines where it is not possible to parallel sufficient MOSFET transistors. Costs Plasma torches were once quite expensive. For this reason they were usually only found in professional welding shops and very well-stocked private garages and shops. However, modern plasma torches are becoming cheaper, and now are within the price range of many hobbyists, less than $300. Older units may be very heavy, but still portable, while some newer ones with inverter technology weigh only a little, yet equal or exceed the capacities of older ones. See also Air carbon arc cutting Laser cutting List of plasma (physics) articles Plasma arc welding Water jet cutter Welding References External links HowStuffWorks on plasma cutting Manufacturing Network >> Knowledge Base - What is CNC Plasma Cutting? Plasma Cutter Safe Work Method Statement Cutting machines Metalworking cutting tools Plasma processing Articles containing video clips Numerical control