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#61
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Re: CNC Tooling
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For a router in particular - the best option is using a carbide single flute tool. Carbide can run high SFPM numbers in aluminum, so that way if your router is 8-10K minimum speed you won't be burning up the tool. Single flute does two things well. Firstly, it gives a ton of room for the chips to evacuate so that they don't pack up in the gullets of the end mill and cause the tool to load up with aluminum, stop cutting, and snap. The second is derived directly from the speed and feed formulae. Say each tooth needs to be taking 0.002" per revolution so that it doesn't start "rubbing" as opposed to cutting. If you have one flute, that means you're only moving 0.002" per revolution of the tool. If you have a 4 flute tool, each tooth needs to take a 0.002" bite, so you have to move 0.008" per revolution of the tool to maintain proper chip load. On a router that can be the difference between a manageable feed rate, and something that the machine cannot achieve. For example - you have a router that can vary from 10K to 20K RPM and you're using a 1/4" end mill to slot. I would use a single flute uncoated carbide end mill. Depending on the specific tool, SPFM in 6061 can be anywhere from 800 to 2000 SFPM. You can run slower, but running fast will wear the tool prematurely. A 1/4" tool running 800 SFPM is 12,200 RPM. Perfect, right in the range for our router spindle. Now finding the feed rate is just (spindle speed * # of flutes * chip load). Say we're being conservative and taking 0.002"/tooth. That means our feed rate is only 24 inches/min. Any machine on the planet can do that without worrying about acceleration in curves, angle changes, etc. If we want to go faster, we can bump up to 20k on the spindle (~1300 SPFM, likely fine for carbide), and the feed rate jumps up to 40 inches/minute. Perfectly achievable numbers, the tool isn't going to burn up or rub, and we have a ton of room for chips to jump out (only one flute!). If you like 1/8" end mills, then you can run 24 IPM at 12,200 RPM (0.002"/tooth and only 400 SFPM), or 40 IPM at 20k RPM (0.002"/tooth and 650 SPFM). Using a two flute cutter doubles those feed rates while keeping the spindle speed the same. Three flute triples, and so on. But now you have increasingly little room for the chips to evacuate, especially with a smaller 1/8" end mill. Your previously reasonable 25-40 IPM feed is now up to 100-160 IPM on a 4 flute tool, and you'll need to be taking a shallower cut if you run out of HP in your spindle. As for the first part - TiAlN is perfect if the situation is correct. Here's Niagara's chart: http://www.niagaracutter.com/techinf...d_solcarb.html Say we're cutting 300-series stainless (over 32 rockwell C). We would probably want to be using an air blast to clear chips, and let the coating do the work. We need to coating to heat up to work properly, so here we don't want to be under the recommended SFPM numbers. So say a 3/8" 4 flute end mill - chart reads 100-150 SFPM and 0.001"/tooth. TiAlN coating adds 60-100% increase in SFPM. So we're somewhere between 160 and 300 SPFM. Let's use the high end - that gives us all of 3,000 RPM and 12 inches/minute. That's why most big VMC's don't really need insane spindle speeds unless they're running aluminum, copper, brass, etc. Even with the coatings, most jobs in steel, stainless, titanium, etc aren't going to going that fast. After that you'll have to start reading about HSM and radial chip thinning, etc, but that's way beyond the scope of this. Last edited by scottandme : 26-08-2013 at 01:40. |
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#62
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Re: CNC Tooling
Well I am confused then.
Cause I not 7 days ago used a TiAlN 1/8" end mill, 2 flute on aluminum. With coolant and it was hardly a new end mill for that purpose. I am not the only one either. So I guess the question I have is at what operating temperature is this coating appropriate? Since the question here appears to come down to whether or not it can reach that temperature. Answering my own concern: I have a long commute so I decided to call around to Duramill and Niagara. Spoke with the technical folks not sales. The reason the coating operating temperature is not specified is apparently because they consider the TiAlN coating inert. It shouldn't want to bind chemically to aluminum any more than Titanium (no affinity according to Niagra). The coating provides hardness and durability till the yield temperature well over 1,000 degrees Celsius. This differs from aluminum titanium nitride which is high in aluminum and therefore is an active coating. The issue they clarified is that aluminum will of course melt well into the safe operating temperatures of these bits. So you don't have to hit a certain temperature to make them work. However just because the bit will withstand these temperatures does not mean the aluminum you are working won't melt and wet the bit. Obviously once the aluminum melts and wets the bit welding will soon follow. The reason my machines are not experiencing that issue is because I do not cut aluminum without coolant. Therefore I am cooling everything. I do not consider the cooling to be really heavy duty so the bit does get hot. However the aluminum being worked is basically a heatsink and the coolant cools that. The gantry mills I have used TiAlN with are pretty rigid. I have seen much worse. Also I am aware that aluminum tends to melt so I take measures to keep moving. This is why there is no minimum desirable operating temperature specified. This is also why it works for me. I told both companies that I've used these with aluminum and no huge red alarms went off. However I still agree a slower spindle is desirable for this purpose. It would eliminate the need for the tool that could be a bit more expensive. Additionally it would reduce the risk that a slow cut would weld. Last edited by techhelpbb : 26-08-2013 at 19:56. |
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#63
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Re: CNC Tooling
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That last one is big, even though it doesn't sound like it. The more people you get to use it during the offseason and the more hours that you have people working it during the offseason, the more parts you will feel comfortable with being cut on it. Also, the more people you have on it, the more efficient your team can be in cutting on it, since one person could run the machine, and the others that can CAM will be making the tool paths. If anyone has any more questions feel free to ask. I haven't read through the entire thread as of right now, but I'll try to get to it. |
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#64
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Re: CNC Tooling
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What did you do for your vacuum set up? Our team made our vacuum from a board with a ring cut around it for a o ring like thing, then we used 2 shop vacs to pull the material down. We've had some success using it with plywood, but we just can't get aluminum to stay still. |
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#65
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Re: CNC Tooling
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#66
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Re: CNC Tooling
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Either way - the proof is in the products that they sell. Duramill and Niagara don't put that coating on their aluminum-specific end mills. They both sell either uncoated or TiCN coating on those tools. They're both a bit behind the curve on aluminum coatings it seems, since ZrN and TiB2 are being used in many other mfg's high end aluminum products. We've used the Niagara aluminum specific end mills with TiCN since McMaster sells them and it's convenient (AN3xx series). They work well, but I can't speak to if they're appreciable better than uncoated - we don't push our machines that hard and they're not being run 24/7 to notice any difference in longevity. I have never seen anyone sell an aluminum specific end mill with TiAlN on it - uncoated, TiCN, ZrN, TiB2, and DLC are the only ones I can remember seeing. I've also never seen aluminum as a recommended material for TiAlN or AlTiN. Quote:
If it's on a mill and not a router, then you still want to use carbide if only for the rigidity benefits. |
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#67
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Re: CNC Tooling
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If you tried to run one of those end mills under aluminum specific parameters (1000+ SFM, .003"+ chip load) you will load it up and break it-guaranteed. This is as much because of the geometry being wrong as it is because of the coating, as the only tools that are ever coated with those are meant for ferrous materials. I'm not sure why they told you that you don't want to run the tool at elevated temperatures. I forget where it is exactly, but somewhere between 700-800C the coating dramatically increases in hardness. As previously mentioned this is why people don't cut ferrous metals with coolant when using those coatings. |
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#68
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Re: CNC Tooling
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I called both because I was curious if one would say the opposite of the other. I've never experienced the issue you have. I did expressely mention that other people were telling me they were having issues with TiAlN in aluminum and they both stated it depends on a lot of factors like the feed rate, the coolant, the rigidity. So your mileage may well differ from mine. Quote:
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The core advice is still the same. Quote:
1,000SFM with an 1/8" mill gets you a spindle RPM of around 30,500 RPM. With a tooth load of 0.003 and 2 flutes you get: about 183 IPM feed rate. I have a lot of people I've worked with that only dream about 183 IPM feed rates their systems could not achieve that. They would be missing steps. If you increase the diameter to 1/4" you'll get down to about 15k RPM and 91 IPM or so that's more practical for large steppers and closed loop servos. Quote:
http://www.geocities.ws/sarangrh/report/seminar.pdf Quote:
http://www.pvd-coatings.co.uk/coatin...tialn-coating/ Quote:
It does not specifically say you'd want to machine aluminum dry. Quote:
Niagara Cutter A245 Carbide End Mill for Aluminum, TiAlN Coated, 2 Flutes, Square End, 4-1/8" Cutting Length, 1" Cutting Diameter http://www.drillmex.com/img/PDF/NIAGARA/A245.pdf Last edited by techhelpbb : 26-08-2013 at 16:30. |
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#69
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Re: CNC Tooling
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#70
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Re: CNC Tooling
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We got a surplus vacuum pump from a mentor we've been using (looks like a large old KOP thomas compressor) for a small table. I know do do anything of meaningful size you need something decent and beefy. I'd try to find someone local in industry with knowledge in routers (cabinet shops often have some HUGE ones) to point you in the right direction, it can be a tough thing to google if you don't already know what you're looking for. They'll also give you great tips all around on how to run the machine, what to fixture with, etc... |
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#71
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Re: CNC Tooling
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If the feed is too extreme for the router, just drop the spindle speed. If you're cutting aluminum on a router you should really skip the silly hand routers and buy a model with a VFD controlled spindle anyway. Good uncoated carbide is perfectly happy at 1,000 SFPM and up. For mills - you're going to be spindle speed limited in aluminum on most cutter sizes, but they're able to maintain higher feeds without issue. Even the Haas TM machines are rated for 400 IPM, and that's still plenty considering the machine size/HP. Your feeds will be much slower just based on the max RPM for the machine. 1/4" 3 flute end mill - 6000 RPM, 54 IPM @ 0.003"/tooth. 1/2" 3 flute end mill - 6000 RPM, 90 IPM @ 0.005"/tooth. You will probably get higher MRR at lower RPM just because the HP falls off on the Haas machines at higher RPM's anyway. Quote:
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#72
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Re: CNC Tooling
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Here: Niagara Cutter 86002 Carbide Square Nose End Mill, Inch, TiAlN Finish, Roughing and Finishing Cut, 30 Degree Helix, 3 Flutes, 1.5" Overall Length, 0.125" Cutting Diameter, 0.125" Shank Diameter The end mill above led me to the end mill below... Niagara Cutter A245 Carbide End Mill for Aluminum, TiAlN Coated, 2 Flutes, Square End, 4-1/8" Cutting Length, 1" Cutting Diameter Which gave me a reference to search for this... http://www.drillmex.com/img/PDF/NIAGARA/A245.pdf Here's the 1/8" TiAlN end mill for sale as factory stock: http://www.kaufmanco.com/itemdetail/NIA%2061489 Parting that series at the same distributer: 61351 = Uncoated = $13.98 http://www.kaufmanco.com/itemdetail/NIA%2061351 61443 = TiCN = $24.21 http://www.kaufmanco.com/itemdetail/NIA%2061443-030 61480 = TiAlN = $15.63 http://www.kaufmanco.com/itemdetail/NIA%2061489 Last edited by techhelpbb : 26-08-2013 at 17:39. |
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#73
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Re: CNC Tooling
The first EM listed isn't for aluminum. No idea about the second one. Looks like you found an outdated catalog page from a French tool supplier. Note how TiCN is the one highlighted as "recommended".
Here's the real A245 catalog page from Niagara's website in case anyone else is interested (uncoated or TiCN only). We've used the A345 (3 flute) with great success, they're good quality end mills. http://www.niagaracutter.com/solidca...um_ss/a245.pdf It's pretty clear you have your mind made up and don't want to listed to what Cory and I are saying. For anyone else following this boondoggle - here's what I would recommend. Using a router? Buy Onsrud's singe flute cutters (63-600 series) - McMaster under "Router Bits for Aluminum" (ex PN 3317A21, 3317A25). Using a mill? Check out Maritool (Uncoated, ZrN, DLC) or Lakeshore Carbide (ZrN). McMaster sells the TiCN Niagara tools (High-Performance Carbide End Mills for Aluminum). http://www.maritool.com/Cutting-Tool...201/index.html http://www.lakeshorecarbide.com/vari...raluminum.aspx |
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#74
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Re: CNC Tooling
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Even your own link points to the same part numbers. Even if you want to say they don't make these any more you wrote they did not make them at all. Quote:
I *only* use TiAlN mills with specific circumstances and *never* suggested otherwise. I am very disappointed in the way you are reacting to this. However it is utterly irrelevant to the fact that it does work. Before it was implied that people were surpised that Niagara would suggest the applicability of TiAlN even though they don't sell it well that can't be a fact. If you simply look through the Niagara price list the TiAlN end mill part numbers are still very much in there. Both the PDF and the ASCII price list dated January 7th, 2013. Old or not they obviously have experience with this coating on aluminum. Now if I were in Niagara's shoes and I was selling a product that a whole bunch of people made a directed effort to dismiss I would probably shelve it as a matter of business as well. Regardless of the product quality or track record if enough customers simply decide it is not for them the volume of sales would plummet (like what would happen if a bunch of people kept going after people over it...sort of like what people often do to BobCAD and MasterCAM). It sure seems like this is a little too much peer pressure for a simple matter like this. So I guess I know why Niagara outright said to me it's just not worth worrying if they disagree. I haven't even bought these products from Niagara so I guess this is an issue they've had pushed on them before. Besides on their actual page: http://www.niagaracutter.com/news/fall99/ Maritool also has this: http://www.maritool.com/Cutting-Tool...duct_info.html So on this I agree to respectfully disagree. Frankly I just get paid too much to sit around worrying about whether TiAlN is acceptable to anyone. http://www.emastercam.com/board/inde...howtopic=33219 http://blog.cnccookbook.com/2012/03/...tting-success/ (list item #3) http://www.practicalmachinist.com/vb...-tialn-121066/ (note the top post and who) This little game of cat and mouse has after all been played out over and over. Last edited by techhelpbb : 27-08-2013 at 02:21. |
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#75
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Re: CNC Tooling
This thread inspired me to try to push my endmill a little harder on a big job I'm doing the first run of.
Lakeshore Carbide 1/4" carbide square corner 3-flute variable helix ZrN coated. HAAS Mini Mill @ 6000 RPM. Flood coolant. Cutting .2 deep, 20% stepover. It's loving running at 144 IPM. If I had a 12k RPM spindle, I'd probably be able to run it at 300 IPM. HSM toolpaths really do wonders. |
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