Use cases ·

EDM, the importance of graphite as an electrode

EDM or electron discharge machining, is a process for the manufacture of molds and parts in various industries, as it increases productivity and reduces the number of operations to generate a product. It is a very precise technique, with good to excellent surface finishes and process repeatability.

EDM, the importance of graphite as an electrode

In contrast to traditional machining, it allows tighter tolerances and a very controlled process, reducing the breakage or deformation of the parts.

Therefore, today we are going to explain what EDM is, how it works, its characteristics and the advantages of its use in different industries.

What is die-sinking EDM??

It is a discharge machining manufacturing process that uses a graphite electrode to erode any programmed contour or volume on various metal parts.

Thanks to these characteristics of the process, unique part geometries can be generated. For this process, the die-sinking EDM machine performs the machining of:

  • Complex geometries
  • Close tolerances
  • Microstructures
  • Parts with extremely fine surface finish

Therefore, it is a widely used option for die-cutting cavities with a conical exit, facilitating the ejection of the parts.

The function of the die-sinking EDM machine is due to a mechanized process of electrical discharge through the graphite electrode, by which thousands of sparks are discharged on a metal part.

As a result, instead of cutting the material, EDM melts it, producing an extremely precise cut line with little waste formation.

The die-sinking EDM machine

It is important to mention that the die sinking EDM machine is made up of different parts, these are:

  • Frame: basically it is the skeleton of the machine, it has different shapes according to the purpose and industry.
  • Headstock: carries the Z, U and V axis movement system, as well as the devices to direct the electrode.
  • Work table: here the part to be eroded is fixed and serves as a dielectric fluid container.
  • Filter unit: in the dielectric tank there is a pump that lifts the liquid to the working area. The filter cleans the particles coming from the erosion.
  • Generator: it is in charge of discharging for erosion.

The EDM process is relatively simple, the part to be eroded is adjusted and the machined electrode is positioned to the desired shape. The part to be eroded is immersed in a dielectric liquid and the electrode is immersed and an electric current is passed through it.

The speed of penetration or stamping is proportional to the amount of electric current as it discharges millions of sparks on the metal surface melting it and facilitating the penetration of the electrode.

As mentioned above, the electrodes used are graphite electrodes of EDM or EDM grades.

Graphite electrodes

They are the standard in the industry as the material offers the following characteristics:

  1. It is resistant to thermal shock
  2. It has a low coefficient of thermal expansion (3 times lower than copper), which guarantees the stability of the geometry during EDM.
  3. It does not melt, it passes directly from the solid to the gaseous state and reduces contamination of the dielectric fluid.
  4. It is capable of transmitting higher currents, thus reducing machining times.
  5. Wear is lower at higher currents.

Graphite electrodes can be machined on milling machines with extreme precision. Depending on the product to be produced, positive or negative electrodes are machined on the part, according to the geometry to be produced.

In addition, it is common to use different electrodes for EDM in two or more steps. In this way a first removal of material is carried out in a more aggressive way and a second step with a finer electrode and at a lower speed to achieve the final finish of the part.

Examples of Die-sinking EDM

Die-sinking EDM equipment is capable of manufacturing parts for all types of industries. Among them are applications in the medical, automotive, aerospace and even the packaging industry. Some specific examples include:

  • Injection nozzles (Automotive)
  • Manufacture of molds and dies for plastic injection.
  • Manufacture of microstructures for medical applications
  • Thermoforming molds
  • Forging molds

Die-sinking EDM is an affordable alternative that allows complex geometries that would not be possible with other types of machining.

In ESGRAF we have graphite grades for EDM, also known as EDM graphite for its acronym in English (Electron Discharge Machining). We have a large inventory for immediate delivery for the uninterrupted operation of your processes. Do not hesitate to contact us to offer you the best alternative in graphite.