Misconceptions about EDM processing in Mould companies

EDM is an important process method in mould manufacturing, especially in injection mould manufacturing is playing a pivotal role. At present, there are still a lot of mould enterprises' technology level is not perfect, some misconceptions in the process often lead to the EDM of mould parts can not reach the intended accuracy, efficiency requirements.

Common misconceptions about EDM
 
Misconceptions about positioning methods The control and guarantee of accuracy in EDM depends to a large extent on the positioning accuracy. In the commonly used Z-axis machining, the X and Y axes ensure the required cavity position and the Z-axis ensures the depth of the cavity being machined. There are various methods to achieve EDM positioning, and the positioning method of using the electrode to make contact with the work piece for perception is widely used in the mould and die business.
 
1 Direct contact  positioning between electrode and work piece
 
Direct edge contact between electrode and work piece is difficult to guarantee a positioning accuracy of 0.01mm even if the work piece and electrode are wiped clean, because of the large contact area, the burrs on the electrode or work piece, the presence of fine debris, the flatness, parallelism and perpendicularity of the electrode and work piece, etc. For work piece (electrode) deformation or electrode is too large (too small) and the accuracy requirements are quite high, there is and can only be used indirect positioning method, that is, using the reference ball for indirect positioning This positioning method can eliminate errors to the maximum extent because of the use of point contact.
 
2 Indirect positioning of the reference ball
 
In the case of complex work piece shapes, the positioning of the reference ball can be easily achieved; the electrode to the reference ball to find the centre of the process to avoid the electrode for a large stroke of movement, saving operating time; for multiple workpiece processing, there is no need to use the electrode multiple times in the centre, as long as the reference ball can be divided once in the centre, saving a lot of operating time, the advantages of multi-electrode processing is particularly obvious. The main electrode materials used in EDM are copper, graphite and copper-tungsten alloys.
 
3 Using EDM to remove the remaining R-angle of the tool after cutting, which is the more common type of machining, also known as "corner cleaning". When this type of machining is carried out, it is possible to avoid unstable discharge due to the small area of the machined part by using the X, Y and Z-axis method, i.e. oblique machining.
 
The current EDM technology has made great development, such as advanced CNC EDM machine tools have emerged, can achieve high efficiency precision machining; fast clamping and positioning system (EROWA, 3R) does not need to repeat correction and positioning of electrode and work-piece, greatly improve the operation efficiency of processing; mixed powder processing makes a large area of mirror surface processing become a reality. In the case of rapid development of mould manufacturing technology, mould enterprises should tailor a set of reasonable process according to their own manufacturing needs, and constantly go to improve, so that enterprises in the competitive trend in the invincible.