Through the popularization for many years, CAD technology has already widely been used in the trades, such as machinery, electron, spaceflight, chemical industry, building,etc.. It use get up for technologies at CAD arrive it raise by the design efficiencies of enterprise, Optimize the function, such as plan of design, labour intensity of lightenning the technical staff, standardization shortenning design cycle, strengthen designing,etc.. In recent years, of our country CAD the development and use and make considerable developments of technologies, Except that have carried on Chinesizing and secondary development to a lot of foreign software, many CADs
