Aluminum doesn't really like EDM. It is possible to cut it but it has some special needs. Aluminum creates a non conductive oxid layer very quick and the material removal rate needs to be high enough to remove material faster then it can oxidize.

The default settings for the G-EDM are made for steel and won't work with aluminum. The forward motion is blocked heavily which can add delays where oxidation can progress and the cutting frequency with 20khz creates finer sparks that don't remove large chunks of material.

I made a simple settings file for Aluminum that runs with 10khz. I don't find the time yet to optimize it but it seems like a good starting point. The cut was done in a single pass without any major issues and no pause but precision is lacking and requires a makeover.

https://github.com/G-EDM/G-RBL-experimental/tree/main/settings