In the production practice, the author found that the deformation and crack in WEDM are related to the following factors.
1.1 it is related to the structure of parts
1) The size of deformation is related to the complexity of shape, the ratio of length to width, and the ratio of cavity to frame width. The more complex the shape, the larger the ratio of length to width and the ratio of cavity to frame width, the greater the deformation of the die. The law of deformation is that the middle part of the cavity is shrunk in, and the punch is usually warped;
2) It is easy to crack or even explode in the sharp corner of quenching cavity with complex shape and clear angle. The frequency of its occurrence is related to the material composition and heat treatment process;
3) Cylindrical parts with thin wall thickness are easy to deform if they are cut on the inner wall, which generally changes from round to ellipse. If it is cut through the notch, it is easy to crack when it is about to be cut through;
4) The deep notch cut in from the outside of the part is easy to deform. The deformation law is that the mouth is retracted. The deformation amount is related to the depth of the notch and the material properties.
1.2 related to hot working process
1) The parts whose initial forging temperature is too high or too low and the final forging temperature is low when forging die blank;
2) When the final forging temperature is too high, the grain grows up, and the cooling rate is too slow after final forging, and there are net carbide precipitated in the die blank;
3) The forging billet annealing is not carried out according to the spheroidizing annealing process, and the parts with spheroidized pearlite more than 5 grades are annealed;
4) When the quenching temperature is too high, the austenite grain is coarse, which reduces the strength and toughness of the material and increases the brittleness;
5) The quenched parts are not tempered in time and the parts with insufficient tempering.
1.3 related to machining process
1) If the die with large area is cut off in the middle without hollowing out in advance, the size of the frame will be deformed due to cutting off the larger volume in the frame;
2) No matter what the shape of punch tempering and shape is, it is easy to deform, especially for the quenched part, which has to be cut in from the outside of the blank;
3) For the grinding parts after heat treatment, there are no process requirements such as grinding wheel granularity, feed rate, cooling mode, etc., and the parts with defects such as burn and microcrack on the surface after grinding.
1.4 material related
1) There is serious carbide segregation in raw materials;
2) Materials with poor hardenability and easy deformation, such as T10A, T8A, etc.
1.5 related to wire cutting process
1) It is easy to deform due to improper selection of WEDM path; Dongguan computer gong Processing Factory Dongguan Mechanical Parts Processing Factory Dongguan plastic mold factory Shenzhen computer gong Processing Co., Ltd
2) It is easy to deform due to unreliable clamping method and improper selection of clamping points;
3) Improper selection of electric gauge may lead to cracks.
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