11. Orbits and electrode reduction
In EDM by spark, the machined part becomes about 0.005 - 1.0mm larger than the shape dimensions of the electrode. This amount differs by the power of the spark, and a stronger spark makes it larger. In EDM, strong sparks and weak sparks should be used properly. The stronger the spark is, the rougher the surface becomes, and machining becomes faster.
In general, in the early stages of rough machining, "strong spark" is used, and at the finishing stage, 'weak spark" which can make fine and clean surface is used. However, "weak spark" cannot be generated after using "strong spark" because the gap between the metal and the electrode is already too big. You can make a slightly larger electrode newly, but it will cause cost problems etc.
The machining control method which was contrived for that is "orbit".
"Orbit" means "swing", and it is a machining control function of swinging electrodes.
By using "orbit", you can use "weak spark" even after using "strong spark", because it can reduce the gap between the electrode and metal.
Move the mouse over the image to see an animation.
And, the amount of swinging the electrode is called "amount of orbit," and electrodes are manufactured smaller by estimating this amount beforehand. This amount of making electrode size smaller than objective size is called "electrode reduction amount".