What Are the EDM Wire Materials for an EDM Machine?
The EDM wire materials are the materials that are used to be the electrodes of an EDM machine, which are fed over the workpieces and discharge the electric energy as the form of thermal energy that removes the materials off from the workpieces.
Just like the electrodes that are applied in the die-sinking EDM machine, they are the media that transfer electric energy to the workpieces, so they should be electrically conductive that they are able to perform their duties.
The most common EDM wire materials are brass EDM wire and coated EDM wire. The brass EDM wire is the traditional type of the EDM wire materials. It is presented as a single-layer structure, which is formed by the alloy of copper and zinc.
The different proportions of the elements in the brass EDM wire, which means the varied composition of the brass EDM wire, make the variation in the properties it has. The more zinc the brass EDM wire contains, the greater the discharge characteristics it has.
In other words, the larger proportion of the zinc in the brass EDM wire, the more efficient the brass EDM wire work in the during EDM cutting. However, the more containing of the zinc element makes the malleability of the brass EDM wire reduce, which result in the difficulty in the production of the brass EDM wire.
When the brass EDM wire doesn’t work if the manufacturers pursue greater properties and less limitations to the proportion of zinc in brass EDM wire, there are other options for the EDM wire materials.
One of the other options is the zinc coated EDM wire. The coating on the brass EDM wire can be pure zinc or zinc-oxide. Since an additional layer of zinc covers the original EDM wire material, it is hardened and thus more stronger than the original one.
As the properties of the zinc coated EDM wire is improved, it takes more time to be broken, facilitates the discharge of electric energy faster, ensures better accuracy, and provides smoother surface finishes for the workpieces.
The other option is the diffusion-annealed EDM wire. The diffusion-annealed EDM wire contains even more zinc element in the original EDM wire, which strengthens the properties that this EDM wire material has.
With the adding of more zinc, the diffusion-annealed EDM wire has greater tensile strength, faster cutting time, the best performance on the finest accuracy of the cuts. Furthermore, the diffusion-annealed EDM wire allows for a wider range of the workpieces that are supposed to be cut, such as steel, aluminum, and graphite.
What Is an EDM Machine?
An EDM machine is one type of cutting machines without the need of any cutting tool that comes in contact with the surfaces of the workpieces. Instead, the EDM machine utilizes the electrodes or wires to come close to the workpieces without touching them, and the thermal energy that is transformed by the electric energy is the cause of the cuts on the workpieces.
There are two types of EDM machines, which apply different media to play the role in discharging electric energy to the workpieces, including the wire EDM machine and die-sinking EDM machine. The former uses the wires and the latter uses the electrodes to perform the discharging duties.
As the above introduction has mentioned, the materials of the electrodes as well as the EDM wire materials should be electrically conductive, and so does the workpieces. In other words, there is the limitation of the materials of the workpieces. Since if the workpieces are not conductive, they are not suitable for EDM cutting.
Due to the most significant characteristic of the EDM machine, which is that the cutting media, either electrodes or wires, are never contact the workpieces, this machine allows for more complex cuts and reduces the frequency of distortions, which may be occurred when the cutting tools contact the workpieces.
In addition, the electric energy that the EDM machine discharges can be very strong or controlled as lighter with fewer sparks being delivered, which makes it capable of cutting either harder materials or thinner materials such as sheet metals.
Right because of the adjustability of the strength that the discharging of the electric energy can be, the EDM machine can usually achieve smaller and deeper cuts on the workpieces as well. Therefore, some manufacturers would prefer the EDM machine to the traditional cutting machines.
How Does a Wire EDM Machine Form?
The wire EDM machine is usually combined with the CNC system, which controls the cuts automatically with even greater accuracy. There is a table that contains dielectric fluid, usually the deionized water, and the workpieces would be immersed in the fluid for conducting electricity as well as serving as the coolant.
Over the table is the EDM wire feeding system. The system consists of a wire coil, a wire guide coil, and a control unit. The wire feeding system is extended under the table with the control unit that is symmetrical to the upper one, and the collection coil on the opposite side of the upper wire coil.
How Does a Wire EDM Machine Work?
In the last section we have known that the wire EDM machine is controlled by the CNC system, and the CNC system allows the wire EDM machine to be operated from three dimensions, including x, y, and z axes.
The x-axis and y-axis refer to the movements of the workpiece, which means that the workpiece would be moved from the x-axis and y-axis according to the instructions of the CNC system.
As for the z-axis movement, it is talking about the feeding of the EDM wire material. When the wire coil is actuated, it would start to feed the EDM wire through the wire guide coil and the control unit, and move downward to the workpiece.
Once the EDM wire is fed until it is close enough to the workpiece but not to touch it, the EDM wire would discharge the electric energy as the form of the sparks, which brings the workpiece with heat. As the material of the workpiece is melted on the required site, the cut is made.
With the cut being made, the wire would also be partially eroded, so the feed of the wire coil should be continued. At that time, the residue of the EDM wire that has undergone the cut would be accumulated in the collection coil for recycling.
During the entire processes, both the workpiece and the EDM wire being fed should be made sure to be immersed into the dielectric fluid, which is usually the deionized water, since the fluid ensures the conductivity of the electric energy from the EDM wire to the workpieces.
Furthermore, the discharged electric energy, which are the sparks, are very strong and thus bring with heat with extremely high temperature. Therefore, the deionized water here would act as the coolant for the cutting site, in order to prevent the danger of burning from happening or too large cuts from being made.