Hi again brainvillehtw:
The thing with "spin-and-burn" which is what you're describing is that the EDM control does not have any influence over the rotation rate of the rotary.
This means a couple of things.
First, the rate at which material will be presented to the wire is no longer fully within the control's influence, so it cannot fully compensate for the cutting conditions in the gap in the same way it can when the block is static.
Second, the apparent thickness of the material is not what it seems so there is no standard tech you can use and you have to go back to first principles to find cutting conditions that can cope.
Imagine you're roughing and you spin the workpiece very fast.
The rate at which new material is presented to the wire for it to burn that material away is influenced by the DOC and by the spindle speed, as well as by the rate of advance, which is the only thing the control can influence.
So in effect you've set the feedrate absurdly high for the spark energy you've told it to use, and you must back it off correspondingly so the gap doesn't choke and short or break the wire.
This is likely why you are not seeing the expected result of your skim passes; you're telling the control to effectively remove far more material per unit time than is reasonable for the tech settings.
In addition, there is no "slot", the flush cups are miles away from the burning surface and the water flow is influenced by the spin rate of the rotary.
So you have intrinsically poor flushing conditions for which you also must compensate, and you have non-linear water flow along the wire which will tend to deflect the wire.
The long distance between the wire guides makes this worse, so you need to run higher wire tension to compensate, even when roughing.
This is all completely empirical, which means you can't just look it up in a table, but have to take the time to experiment, and learn what to do.
Lots of Wire Guys typically don't do this easily; we're trained to follow the recipe to get the expected result and when we work strictly according to the recipe, we get the result we wanted, whereas when we deviate from the recipe even in little ways, we get a screwup (usually loss of dimensional control).
There ain't no recipe for this!!!
So grit your teeth, break out the test parts and learn what you need to know in order to make it work.
It ain't magic, but it can be pretty frustrating until you've farted about with it a good bit and learned what works.
Everybody has to cut you some slack while you do this; and you can't accept blame if it takes what it takes, so if there are individuals in your company trying to hurry you along you may invite them to piss off.
Cheers
Marcus
Implant Mechanix • Design & Innovation > HOME
www.vancouverwireedm.com
Clarus Microtech Inc. | Facebook