428 Modern Welding There are many automatic and semiautomatic mechanisms available to perform cutting operations. Multiple-torch cutting machines are used extensively in industry. They cut several exact copies of a desired part at one time. Figure 14-37 shows automatic cutting equipment. Inexpensive metal templates or line draw- ings can be used to guide mechanical or electronic tracers. Practically all pattern tracers and automatic cutting machines and their torches are moved by vari- able speed electric motors known as servomotors. Special cutting torches are mounted on a light, rigid rail. These cutting torches, Figure 14-38, can be adjusted to vary the fl ame tip-to-metal surface distance. This rail, with all its mechanisms, is called a gantry. Both rail and torches are moved on the X-Y (lateral and longitudinal) axes by electric servomotors. As the tracer moves around the pattern, the servomo- tors move the rail and torches to duplicate the pattern. A servomotor gets feedback information from the pattern tracer. This feedback causes the servomotor to move the rail and torches in the proper direction to duplicate the pattern. Once set up, these cutting machines are self-oper- ating. However, the initial adjustments must be very carefully made by the operator: ● Adjustment for the number of in/min (cm/ min) to be cut. ● Gas pressure must be carefully adjusted to ensure a clean cut through the thickness of the metal without wasting fuel. Figure 14-38. An oxyfuel gas cutting torch designed for use on a motorized carriage or gantry-type cutting machine. Figure 14-37. A gantry-type shape cutter. One plasma arc and fi ve oxyfuel gas cutting torches are mounted on this computer-operated cutting machine. The required torch movements are programmed into the computer at the left. (ESAB Welding and Cutting Products)