Electric Discharge Machining is the
best way to re-establish permeability.
This method will burn away the metal fragments that are crushed over the pores by milling and/or grinding. Because of its powdered metal origin, when using a wire EDM machine, it is important to increase the wire speed about 10 % to prevent arcing from the particles produced. Because a wire EDM machine uses water, the insert must be dried in an oven after EDM, or rust and pore closer will ensue.
