电火花复习..doc

什么是EDM Electrical Discharge Machining (EDM) is the process of machining electrically conductive materials by using precisely controlled sparks that occur between an electrode and a workpiece in the presence of a dielectric fluid, so to make the size, the shape and the surface quality meet the predetermined requirements. 2、EDM与传统加工方法的差异 1）electrode does not make physical contact with the workpiece for material removal. 2）EDM has no tool force. 3）electrode must always be spaced away from the workpiece by the distance required for sparking, known as the sparking gap. 4）only one spark occurs at any instant.(except for HSWEDM) (frequency range from 2,000 to 500,000 sparks per second ) 3、绝缘工作液（dielectric material or dielectric fluid） 1）、EDM is a thermal process; material is removed by heat. 2）、where the spark originates and terminates,are heated to the point where the material vaporizes. 3）、This dielectric material is normally a fluid. 4）、Die-sinker type EDM machines usually use hydrocarbon oil, while wire-cut EDM(LSWEDM) machines normally use deionized water. 4、绝缘工作液的主要特点（main characteristic of dielectric fluid） 1）、Controlling the sparking-gap spacing between the electrode and workpiece as an insulator; 2）、Cooling the heated material to form the EDM chip; 3）、Removing EDM chips from the sparking area; 4）、Compress discharge channel cause explosion in channel. 5、电火花加工的必要条件（necessary conditions for EDM）Spark gap 2）、 Dielectric fluid 3）、 Powerful pulse power 4）、 Spark on time is very short 5）、 Enough spark off time 6、EDM的发展历史 EDM originated from the need to perform machining operations on difficult to machine metals. The process was developed almost simultaneously in the USSR and the USA at the beginning of World War II. In 1943，the First EDM In the World In 1943, the Lazarenkos developed a sparkmachining process with an electrical circuit that used many of the same components as the automobile ignition system. This process became one of the standard EDM systems in use throu