Molybdenum wire cut EDM is original in China, and widely used in molds, precision parts making, here are some basic knowledge of molybdenum wire cut EDM machining.
1. Coordinate of workpiece and original zero setting.
1) Several workpieces could be fixed on the working table at different position, but it needs to set up several coordinates respectively.
2) Normally, six coordinates could be set up on the machine, and indicated by G54-G59.
3) The original zero of each coordinate should be easy to measure, touch spark and to be programmed and calculated.
2. Choice of technological parameters
1) Technological parameters refer to machining condition, include: discharging impulse frequency, frequency width, electric current, discharging gap and so on. These parameters are relative to material, heat treatment situation, thickness of workpiece, and accuracy requirement, diameter of molybdenum wire and some other factors affect machining condition.
2) For some CNC molybdenum wire cut EDM machine, they have parameters date base, these dates could be called for use.
3) The called date from base could be adjusted according to actual condition of workpiece and machining requirements.
3. Choose wire thread hole, lead in and lead out line properly.
1) For closed cutting work, it needs to produce wire thread hole in advance, we can get this hole by drilling machine or small hole EDM machine.
2) Wire thread hole is the start where molybdenum wire move forward workpiece, it is also the start position of program.
3) Position of wire thread hole should be easy for alignment and position check during machining.
4) Wire thread hole should be on the workpiece
5) It is also very important for choice of lead-in and lead-out line.
4. Set compensation of radius of molybdenum wire
1) Method of calculating compensation of radius of molybdenum wire: compensation=radius of wire + discharging tap, i.e. D=r+δ(δ is discharging gap)
2) The way of how to set compensation of radius is exactly same as how to set compensation for CNC milling machine.
3) It has to use command G01(command of Line Interpolation) to set and cancel compensation of radius, for HF, it can be set before program list(G code or 3B code) formed, please check figure 1 to get a general knowledge of compensation of radius
Figure 1 compensation of radius a) cutting male die b) cutting female die
1. Condition of angle cutting
1) Basic needed parameters
(1) Distance S between center of up guide and working table
(2) Distance W between working table and center of down guide
(3) Thickness of wrokpiece H, as figure 2 show
Figure 2, relative basic parameters of angle cutting
1) How to establish and quit angle cutting
(1) Establish angle cutting with command G51 or G52, quit angle cutting with command G50,of course, for most software used today, software can form program list automatically, use just need to do some drawing and parameters setting.
(2) Program segment of lead-in and lead-out line should be G01 line interpolation.
(3) The lead-in line of angle cutting should start from G01 line interpolation and end with the position with the preset angle, i.e. molybdenum wire is straight in vertical direction at start point of lead-in line, and oblique with needed angle.
(4) The lead-out line of angle cutting should end with G01 line interpolation and start with the needed angle. Opposite as lead-in line.