This may change your (and my) thinking on surface speeds. But it may require a really rigid machine. I think the key is the tool path and of course the tool. So 7200 RPM, proper carbide endmill, proper engagement and tool path should work.
I've been looking for a suitable brake rotor for my mill turn project but there's just nothing exactly how i want it so I ordered a blanchard ground 8x8 3/16 thick a36 plate. Slowest my spindke can go is 7200rpm, but I think I'll be ok. I'm going to slot cut with a 1/8 carbide emdmill. At 7200rpm I'll be at 235 sfm. Will this be ok? Figure I'll just do shallow passes. What about coolant? I work with mostly aluminum so I'm set up with mist coolant using koolmist. Should I use it? I obviously won't be able to drill the a36 at 7200rpm so I'll just interpolate the bolt holes as well.
Will I be ok at 235sfm? If that's too hot, I can get a smaller endmill. I'm only cutting 3/16 deep so even a 2mm endmill would probably be fine and get it down to 150sfm but I'd rather use what I have if it'll be ok.
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This may change your (and my) thinking on surface speeds. But it may require a really rigid machine. I think the key is the tool path and of course the tool. So 7200 RPM, proper carbide endmill, proper engagement and tool path should work.
Jim Dawson
Sandy, Oregon, USA
You mean that you can't do that on just any Chinese table top router, huh, I'll be darned, who would of guessed?
I have been chatting with QuinnSjoblom on various subjects on this forum long enough to know that he would understand the point of my post and get the joke. And I could tell from his response that he got it, unlike others. HeII, my Haas wouldn't even do that, that DMU 50 in the video has a 50 HP spindle and weighs ~12,000 lbs.
Last edited by Jim Dawson; 05-09-2019 at 10:21 AM.
Jim Dawson
Sandy, Oregon, USA
hello jim, yes, there are a few thingsBut it may require a really rigid machine
on a more rigid machine, you can go faster, but is good to know how to scale the process to fit a less rigid machine
otherwise, is dangerous, even on a rigid machine
on okuma ( lathe, mills ) i use load comparative method, checking load dinamycally to avoid sudden peaks, that may lead in time to signifiant wear
also, diff is cheked, to avoid increasing the backlash
is easy to say, but harder to implement; not impossible
in short, it is required to monitorize the process, observe and adjust accordingly, like mapping the feedrates, and others
also, there are forces that can not be monitorized, but may distroy the machine, especially when going such fast
there are persons that simply avoid such specs, because, even if they work ok, they can not predict or react fast in case of a sudden failure, with not-so-nice consequences / kindly
we are merely at the start of " Internet of Things / Industrial Revolution 4.0 " era : a mix of AI, plastics, human estrangement, powerful non-state actors ...
Haha! Nope, I totally took that as "you should crank it up to 19k and just let it rip" lol.
Totally understood Jim's post. obviously I can't do that with my machine, but at the same time I think it shows what modern carbide tooling can do these days and standards for specific sfm in specific material is definitely not set in stone.
So here's what I'm curious about in that video, limits are being pushed without coolant. Is this common practice for steel? I generally don't mill steel so I just don't know. I would think the main limitation when pushing limits is heat, so would think coolant should allow the limits to be pushed further, or does it just create more problems like thermal shock? I imagine the biggest heat remover is the chips leaving the cut and taking the heat with.
Great question. And I don't know. I have always use coolant (and much slower surface speeds) but ''that's the way we have always done it''. You are correct that most of the heat (should) leaves with the chips. But in the video, with the exception of the spiral plunge cuts, the chips don't even seem to change color. I need to kinda re-think some of the stuff that I ''know''.
Jim Dawson
Sandy, Oregon, USA
hi quin, i noticed that you + jim = love
i don't have jim's patience
about 'modern' carbide, i set up long term setups. and differences between low quality carbide and high quality are like 1-2 hours versus 4 shifts, on same cuting specs
depends, but less tool changes are better, and also less offset corections is better / kindly
we are merely at the start of " Internet of Things / Industrial Revolution 4.0 " era : a mix of AI, plastics, human estrangement, powerful non-state actors ...
some tools, especially when milling, may break because of thermal fluctuation : for example, if the tool is cutting between 0*-45* and coolant is on 0-45, then, things are 'stable' as long as the coolant flow is stableso would think coolant should allow the limits to be pushed further
if tool is changing cutting side, to 90-135*, but there is no coolant in that area, then a termic shok apears when leaving / entering the coolant zone
solution :
... through tool coolant
... coolant flood ( using showers, etc )
some tools are sensitive to termic shock, so, is better to go 'dry', as long as coolant flow is not uniform arround the tool; from this perspective, some tools are designed to go 'dry'
on some setups, there is a reaction between the colant and the material, near the cuting edge, which is not benefic for the tool; about this last thing, i did not experimented it, i was only told / kindly
we are merely at the start of " Internet of Things / Industrial Revolution 4.0 " era : a mix of AI, plastics, human estrangement, powerful non-state actors ...
Don't worry the chips after they leave the cutting area they change color from a straw dark straw to a blue depends on the cut, they may have the air going through the spindle as well, in your case your mister would do a good job, with the air to move the chips will help a lot
Mactec54