Q: Is it acceptable to utilize the same electrode reduction undersize amount for all of the electrodes?
A: The real answer is yes and no, as a proper answer requires a detailed look at the overall EDM operation. The practice of using a standard electrode reduction amount is very common. However, depending on specific applications, it may or may not yield the best machining speed or accuracy results.
Benefit of Using a Standard Electrode Undersize:
In many shops, the electrodes are machined by milling, and different mill programmers typically have varying levels of EDM knowledge. Using a common or standard electrode reduction amount for all electrodes can help streamline and simplify the process of electrode programming, regardless of the operator.
Applying the same electrode reduction amount to all electrodes prevents confusion in EDM setup and tracking. If all electrodes have the same reduction amount, there is no need to mark and/or measure every electrode during EDM setup.
Applying the same electrode reduction to all electrodes lends greater EDM process flexibility, as the electrodes can be shuffled around and reused as roughers and finishers when needing to produce multiple cavities of the same contour (for example: cavity #1 finish electrode becomes Cavity #2 roughing electrode).
Downside of Using a Standard Electrode Undersize:
Using a standard electrode reduction amount can waste valuable shop machining time. With too small of an electrode reduction amount, the EDM operator is often handicapped into using a lower power discharge setting in order to maintain proper size, which results in slower machining speeds and increased electrode wear.
Applying the same electrode reduction amounts between the roughing and finishing electrodes can deteriorate form accuracy, as the finishing electrode is machined further away from the final net shape of the desired cavity and often requires greater optimization. This method can also lead to declines in machining speeds (slower roughing and more required orbiting on finishing).
Intelligent Review on Electrode Preparation:
It is paramount that the EDM operator and electrode milling programmer communicate to discuss plans for electrode reduction on each job.
Through proper review and planning, shops can significantly improve efficiency and apply optimal electrode reduction amounts that produce the fastest machining speeds (roughing speeds often see the largest improvements).
The use of different electrode reduction amounts can be strategically deployed on critical part details that require tighter tolerances.
It is important to establish a reliable identification system when manufacturing electrodes with different reduction amounts, such as a marking or color code system on the electrode holder for roughing and finishing.
For more open tolerance details, a standard electrode reduction size can be established.