WEDM technology [Principle/Basic knowledge]
WEDM is a kind of electrical process machine, it’s being used to cut metal through the electric corrosion way by molybdenum wire.
Wire cut Electrical Discharge Machine, referred to as WEDM. Its basic working principle is to use continuous moving fine wire (called EDM wire) as electrode,to processing workpieces by pulse spark discharge erosion and cutting way. It is mainly used for processing various complex shape, precision and small workpieces, such as punch, die, punch-die, fixed plate, discharge plate,etc of the blanking dies, metal electrode for the processing of forming tools, sample, electric spark forming, various kinds of micro hole groove, narrow seam, arbitrary curve. Its advantages include small finishing allowance, high machining accuracy, short production cycle and low manufacturing cost, etc. And has been widely used in manufacturing. Currently Wire-cut EDM machine of electrical machine is over 60% of the total through the whole world.
According to the operation of the wire electrode at different speed,Wire cut EDM machine is usually divided into two classes: 1) high speed silking wire-cut edm machine (WEDM – HS), the wire electrode reciprocating motioning at high rotation speed, generally the silking speed is at 8 ~ 10 m/s, wire electrode can be reused, the processing speed is high, but fast silking easyly causes the wire electrode shaking and pausing when reverses, which leads to the decline of processing quality. WEDM-HS is the main model being used in production in China, and it’s chinese original wire cut edm processing mode. 2) low speed silking wire-cut edm machine (WEDM – LS), the wire electrode unidirectional moving at low speed, generally the silking speed is below 0.2 m/s, wire electrode can no longer be used, the working is smooth, uniform, low shaking, processing quality is good, but the speed is low, is mainly been used abroad.
According to different control types of wiree lectrode trajectory, wire cutting machine can be divided into three classes: 1) * imitate shape control, its in wire-cutting processing ago, prefab out with workpiece shape of the same * die, processing the workpiece blank and * die at the same time the clamping in machine tool working stage, in the cutting process of wire electrode tightly stick * die edge for track mobile, thus cutting out and * die shape and accuracy of the same workpiece. 2) photoelectric tracking control, its in wire-cutting processing before, first according to the parts pattern according to certain proportion amplification figure out a photoelectric tracking map, processing will pattern in machine tool’s photoelectric tracking stage, on the track of the photoelectric head always follow the chalk line graphics trajectory, and by means of the electrical and mechanical linkage, control machine tool table together with the relative wire electrode do similar figures movement, thus cutting out and pattern of the same shape workpiece. 3) digital program control, the use of advanced digital automatic control technology, drive machine according to processing ago according to the geometry parameter prepared nc machining program to be automatic.
EDM belongs to electromachining, it’s an invention of former soviet union. Our country is the first to use EDM for industrial production, The earliest model called fudan, is manufactured by fudan university and suzhou changfeng machinery factory at that time. We chinese developed high speed WEDM on the basis of EDM, Europeans, americans and Japanese developed low speed ones.
Main differences between them is as follows;
1) We use the tungsten-molybdenum alloy wire, brass wire used abroad.
2) We use the saponification working fluid, deionized water used abroad.
3) Our working speed is at 11m/s, theirs is at 3-5m/s.
4) Our wire electrode can be reused until broken , it can only be used once.
5) Compared to Low Speed WEDM, our precision is low.