Hi,
As previously asked in a topic with the same name im drilling 1600 d0.3 holes into 0.5mm Al with a pcb drill bit, coolant is spiritus, 5k rpm, 100mm/min
While this generally works good, i have troubles with chip clearing and it wraps around the drill, which breaks it after a while if not removed manually.
Coud someone please give me a hint? (@TDA, @HeuristicBishop ?)
Thanks Michael
Ps: ive swiched to a 2,2kw spindle in the meantime
Are you doing and drilling strategies like pecking? Takes more time but the retract may break the longer chips leading to less buildup.
Unfortunately I wouldn’t know what parameters to offer. If it were me, I’d try pecking once per hole. Essentially retracting half way through the material then coming down again to finish the hole.
I gotta believe with that tiny of a cutter you’re gonna want the RPM as fast as it will go.
FSWizard recommends 182000 rpm with no max RPM set.
I’m not familiar with Spiritus coolant. Your coolant/lubricant should be formulated for aluminum/soft metals. I like Tap Magic - Aluminum.
Not sure what your max RPM is, but at 24000 RPM I get 95mmpm for a 0.002mm/tooth chipload.
I’ll try packing. Higher rpm (24k) didn’t seem to have an influence. In the meantime I tried to get rid of the tiny pcb bit and used a 90° chamfer bit which is much more solid. Then milling the pocket from the other side down to get the right diameter of the actual hole. First tests showed reasonable results. I’d have to fine tune it a bit more
Usual preface, I’m with PreciseBits so while I try to only post general information take everything I say with the understanding that I have a bias.
Sorry, didn’t see this until Monday and Monday is always… a Monday.
Couple quick questions first.
Is this “ribbons” of aluminum wrapping around the cutter or aluminum packed into the flutes?
I’m going to join the club of I have no idea what spiritus coolant is. So I can’t say if this is helping or hurting you. Any links to it?
I’m assuming the same material (99.5% Al)?
How deep did you end up needing to go?
Do you know your runout?
From that picture it doesn’t look like you’re feeding that tool enough. Might also be geometry, some chamfering tools aren’t made for plunging or have very little rake.
Assuming that you’re still using the same type of aluminum as before, and you want to go this route, I’d try a PCB trace isolation tool instead. Those are made to cut copper and should do a good job cutting soft aluminum. Just make sure it’s actually a tool designed for it and not a general use “V” cutter.
Let me know what you can of the above questions and I’ll reply back.
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