lothar baier wrote:
i remember years and years ago we had a similar problem with another plastic part, we used a part sprayed graphite on it and then plated over a layer of copper, this served as a EDM tool, problem was we had to make 3 of them because they wore out.
most EDMs i looked at have 3 parts, the machine itself, a power supply and a pump that circulates and filters the dielectric fluid, i havent seen a machine with a 50W supply, even the smallest ones are in the KW range, dont know why they use 3 phase , im not the guy who designed the machine, my guess is that it is better in large shops where you have numerous machines to distribute the load , i dont know !
The rate of removal of material is proportional to the machine power. In a shop where you charge by the hour, you want a high production rate.
The EDM setup I described previously ran at roughly 100 VDC at under an amp. Three phase is used because when you FW rectify it, the ripple w/o filtering is only about 4%. Ripple on the supply might lower the surface finish of the part you are making.
Best,
-John
