Good day all -
I’m running a Current small hole drill, brass 0.30 mm OD tube, DI water (25 uS) on a cast nickel-based turbine blade. I’m struggling to meet the max recast allowance (0.0015 in) on some fairly deep holes (20x L/D).
I’ve tried different tube IDs to change the flush, but it doesn’t seem to matter (nor does it matter whether the electrode is new or just about used up). I’ve gone up and down an electrode OD. I’ve tried a lot of power settings, dropping down to where the process is only marginally stable.
Most holes easily conform - but a few random holes will show a spot where recast is too high. Location along the hole is also random.
Does anyone have a trick? I’ve got more things to try, but I’m sort of hunting in the dark.