Q. What kind of parts/applications are we talking about?
A. The range of aerospace components and applications where EDM can be applied continues to grow. If before there were only a few applications, belonging almost exclusively to traditional EDM such as cooling holes and grooves in NGVs, segments, and blades, they have now been diversified to include impellers, IBRs, OGVs, turbine discs, combustion chambers, and fan blades.
Q. What caused this leap in recent years? Was it simply the development of new generators that transformed EDM into a competitive machining technique for the aerospace sector, even when it comes to so-called ‘critical parts’?
A. Obviously, the leap forward in technology has been triggered by new generations of EDM machine generators, but also by advancements in the development of EDM technology. While only a few EDM parameters could be configured previously, now more than 30 configurable parameters can be used. This provides much greater flexibility when it comes to finding the optimal solution. Then, we must acknowledge the work of the OEMs to introduce EDM into critical parts, the drive and tenacity of their engineering and manufacturing managers that were open and prepared to accept, check, and approve EDM for these types of parts. Without them, it would have been impossible to reach this point.
Q. What technical advantages have the new generators brought to EDM manufacturing of, for example, gas turbine discs, rotating parts that reach up to 60,000 rpm and must be prepared to withstand extreme pressure fluctuations and temperatures?
A. In the case of ONA’s new generators, it was the fact that they are digital. Now EDM technologies can be developed such as electrolysis and micro-cracks can be diminished or even eliminated, achieving very low recast layer levels of just a few microns. The surface requirements are acceptable, and the parts can be approved for flying..
Q. What advantages does EDM offer aerospace sector parts manufacturing over more traditional techniques such as broaching and milling?
A. From an industrial point of view, some very interesting advantages have been defined, particularly with wire EDM. Compared with conventional machining using milling and broaching, recurring consumables costs are significantly lower. In respect broaching, wire EDM offers fast and cheap prototyping solutions. Between designing and manufacturing, a broaching tool could require up to a year, while wire EDM is nearly immediate and directly associated with the cut profile’s programming. In addition, this approach does not allow for errors; if for some reason the broaching tool is not right, design modifications have to be made and manufacture a new one. In the case of EDM, after cutting the piece , the profile is measured, and if it must be adjusted, it can be done directly by programming the cutting path. On the other hand, the wire EDM machine’s autonomy is another major advantage. All of ONA’s AV models have the option of using a 45 kg wire spool system, which is nearly 8 times more than a standard 8 kg spool. And when it comes to die-sinking EDM, we can see a trend towards automation using robots and shared or individual electrode storage.