newb talk, 2 flute vs 4 flute cutters


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Thread: newb talk, 2 flute vs 4 flute cutters

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    Default newb talk, 2 flute vs 4 flute cutters

    Could anybody also give me some advice on the differences between the 2 and 4 flute cutters. I bought a center cutting end mill kit which has both types, two flute and four flute.

    Currently, I'm under the impression that a two flute end mill will allow the user to IPM around quicker but leave a poor finish behind, which is where the four flute mills come into play for the finish pass right? Now assuming that this is indeed the case, Could a guy instead just start with the four flute mill and just go a little slower in order to avoid a tool change? What strategy will minimize the number of tool changes for a guy who doesn't have an ATC mill but still leave a nice finish behind on aluminum?

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    Two flute gives more chip clearance for aluminum. It doesn't matter thaaat much. I usually just grab whatever is on hand. You'll find machinists that'll tell you that it matters and machinists that tell you that it doesn't.

    And yes, if you run a 2-flute end mill on steel at 600 rpm then you'll have to go slower to get a real nice surface finish, but on aluminum running a 2-flute at 3k-6k it just doesn't matter that much.



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    Those two-flute cutters may well be slot drills (I bought a Chinese set that has five sizes of matching slot drills and end mills). Slot drills can plunge cut (driven straight down into the work like a drill bit) whereas four-flute end mills will not, as they are not centre cutting. Four-flute end mills generally give a better finish , and can cut faster as they have twice the number of cutting facets.



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    look for the thread in this area that talks about 2 vs 4 flute. more info than you would ever need to know. can't remember what its called. should be only a few pages back.

    bookwurm99



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    Interesting point Philbert, Mine is 20 piece Chinese set all center cutting. I choose these because some of my parts require inner pocketing. So if I'm understanding this correctly, on aluminum the finish different between 2 and 4 flute is negligible and the biggest difference is actually chip load up, which of course effects the feed speed you can run?

    My machine is an older one, so I can IPM around at mach speeds anyways. Maybe 150 IPM at most. Since this is the case, Should I just switch to the four flutes altogether since I imagine my feed capabilities are not that fast compared to some? What happens if you chip over load a cutter anyways? finish gets crappy?



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    I'm no expert, and I steer clear of aluminium (or 'aluminum', mate ). Finish is mainly about the about the amount of work each tooth is doing. Because the cutting speed of aluminium is so high (about 600fpm as opposed to steel at 100 or so), you can run a cutter very fast, and provided your feed rate is low compared to your spindle speed, then a two flute cutter can give a good finish.

    Chip build-up will always mar a good finish because it rubs, and can force the tool out of alignment (digging in, etc). If you get too much chip build up, you could break the cutter. Aluminium is particularly nasty because it likes to bind to the cutting edges. The best cure is coolant to flush the chips away (and keep temperatures in check!) I believe you can also get compressed air setups to blow the chips away (in a safe direction I hope!) in situations where you're not using coolant.



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    General rules of thumb (very general)
    2 flute for aluminum, 4 flute for steel.
    Use of WD-40 while cutting aluminum gives much better finishes.
    Always climb mill aluminum.
    Aluminum likes lots of rpm.

    You can always spot the pioneers -- They're the ones with the arrows in their backs.


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    Quote Originally Posted by DerHammer View Post
    ...
    Currently, I'm under the impression that a two flute end mill will allow the user to IPM around quicker but leave a poor finish behind, which is where the four flute mills come into play for the finish pass right?
    Nope! A two flute will allow you to rough faster AND get a better finish than a four flute. Four flute tools do not have clearance to get rid of chips, so your finish will suffer.

    Generally speaking, in aluminum, I see the best roughing performance with two flute tools and the best finishing with three flute tools. There are some exceptions...for instance, in many instances (but not all), Data Flute ALDH three flute tools can rough faster than most two flute tools. They also have a five and seven flute aluminum specific finishing tool that works very well.



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    Default good to know

    1st off I want to say that I love this site and as a new machinist I really appreciate what this community does for each other. Very cool to see.

    so back to business. Ill stick with the 2 flute cutter and keep it lubed even if I haft to feed at a slower speed. I'm not a production shop and my part runs are relatively small so it doesn't hurt my feelings to move slower as long as good parts are coming out in which require less sanding later. The final product requires polishing and the better the finish=hours saved .

    I found some feed and speed calculation software on "the zone" which recommends higher feed speeds when using 4 flute cutters, which confuses me because it seems counter intuitive to whats being suggested by other users. I'm assuming this is the case because the software probably does not take chip load into account most likely? So putting this back in order then, If 4 flute mills chip load bad on aluminum and you can get a decent finish with a 2 flute cutter... Do my 4 flute mills serve any purpose when cutting aluminum over a 2 flute? If we take an example, I'm going to be using a 1/2 cutter and 1/4 cutter, both HSS for my stuff. I have both versions in 2 and 4 flute. At what IPM and RPM is a good starting place to get the best cut? I also have 5hp spindle if thats a factor also.



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    Quote Originally Posted by DerHammer View Post
    Do my 4 flute mills serve any purpose when cutting aluminum over a 2 flute?
    No. Four flute endmills are way inferior to a two flute in aluminum. A two flute endmill will cut any geometry MUCH faster and with a better finish until you start getting into large tools that have a lot of clearance between flutes. Even with a 0.75" endmill, a two flute absolutely destroys a four flute.

    The difference is significant...expect to feed a two flute at least 3-4 times faster than a four flute in aluminum (same rpm)


    Quote Originally Posted by DerHammer View Post
    At what IPM and RPM is a good starting place to get the best cut? I also have 5hp spindle if thats a factor also.
    More importantly, how much rpm do you have available, and what kind of feed rates can your machine and control handle? What is your spindle's taper size?



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    Quote Originally Posted by DerHammer View Post
    recommends higher feed speeds when using 4 flute cutters, which confuses me because it seems counter intuitive to whats being suggested by other users. ..
    4 flt has more flts which means more material removal/ rev



    .
    Quote Originally Posted by DerHammer View Post
    Do my 4 flute mills serve any purpose when cutting aluminum over a 2 flute? .
    rigidity is far greater with a 4 flt which gives less chatter and less deflection especially with hss tooling

    lots of times the right tool for the job depends on personal preference and experience ,i would by far use a 4 flt above a 2 flt for finish and roughing ops , as long as the chip evacuation is there ,at which most times it is there , go for it , it just takes a little forsight

    i firmly beleave that as far as plunging tools goes ,if it can be avoided then avoid it ,add a drill at the plunge point to remove material and give some clearance for the cutter , this will save time and will deter any deflection issues of plunging an hss endmill ,hss can walk away and oversize quite easily, even carbide can deflect a fair bit before the tool will break which leaves a potential of overcutting when you can t afford to have it happen



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    dertsap,
    Respectfully, No! No! No!

    Quote Originally Posted by dertsap
    4 flt has more flts which means more material removal/ rev
    That doesn't apply with aluminum. With superior chip evacution of a two flute tool, you can make a much bigger chip and get it out of the way.

    Quote Originally Posted by dertsap
    rigidity is far greater with a 4 flt which gives less chatter and less deflection especially with hss tooling
    True, but in this case, a three flute wins. A four flute just cannot move chips, especially with a deep cut, where you would be most concerned about rigidity. Carbide, two/three flutes, shortest flute length is king. Here is one of my parts running a 0.375" two flute endmill, 12000 rpm, 210-460 ipm. I changed tooling suppliers and now I'm running the same part at 250-500 ipm. Don't try this with a four flute endmill.

    (save to your computer first)

    http://www.foreprecisionworks.com/video/MVI_2165.AVI



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    3flt beats the others with no question about it
    i can agree that you have more room for chip with a 2flt , the thing is you can only go for a depth of 1/2 of the tool dia and you can t go to nuts on tool engagement ,so either way you are limited to the amount of material you can remove , but this is where i said it boils down to personal preference and experience , at my job making tools work and deciding which tools to use is my area of expertise (if i have one ) , most jobs i have zero room for error and rarely a spare part , i usually know by looking at the job if a tool will work or not work , i'm not trying to sound like a peckerhead by saying this but my point is these are my preferences thru my experiences , we all have our ways of accomplishing to same goal ,
    like to ol saying there are many ways to skin a cat

    for ruffing i rarely use hss to begin with , if and when i do it is with the proper tooling such as minicut ruffers http://www.minicut.com/Products/catalog_USA_07.pdf
    i for the most part see it pointless to use a standard endmill to hog material , minicut are fairly cheap and tough



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    Quote Originally Posted by fpworks View Post
    Here is one of my parts running a 0.375" two flute endmill, 12000 rpm, 210-460 ipm. I changed tooling suppliers and now I'm running the same part at 250-500 ipm. Don't try this with a four flute endmill.



    http://www.foreprecisionworks.com/video/MVI_2165.AVI
    yup thats haulin
    gotta love it

    are those miteebite clamp your using



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    Yes, you're right...it will definitely get the job done. I just want to open him up to the idea that aluminum cutting sometimes needs a different way of thinking to get best results.

    I remember when I was first learning, stuck in the rut of following simple chipload theory, running 20 or 30 ipm at 6000 rpm with four flute tools, because that is what I had been taught. I broke out of that, and now parts are now getting done a lot faster and with better finishes. Of course, I'm talking about production, which is a LOT different than your approach as a toolmaker. (I'll gladly spend an hour and/or sacrifice a few parts to make a program 15 seconds faster)

    I think for a beginner, a two flute is an exceptional choice...since it will be forgiving when burried into a sharp corner or plunging too fast.


    Yes, those are brass Mitee Bites clamping along through the finished floor of the workpiece, which ends up being 0.050 thick at the end of roughing (yuck). I really like the hardened knife edge variety...a fixture loaded with those clamping both sides of the workpiece is killer.

    As far as that video goes, here's some interesting history on the roughing of that part. All used same toolpath, same rpm, same machine. Limitation was breakage of tool, then backed off 10%. Note the flute count.

    Rev00: 3 flute Promax, 150-330 ipm
    Rev01: 2 flute Garr 242M, 210-460 ipm
    Rev02: 3 flute Data Flute ALDH, 250-500 ipm

    Shows importance of tool geometry as well!



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    great info here guys. I guess I forgot to mention some critical data with my question. My spindle is slow compared to what you guys are dealing with, Its capable of about 3600 RPM. I'm not sure exactly how fast my machine can feed but I'm guessing its around 150 IPM. Its also 40 taper and I have a 5 hp spindle. Machine all together weights about 4000 lbs. Has an older Fanuc OM controller on it.

    So, since I'm using HSS cutters. stick with the 2 flute then for this job. Again I'm using 1/2 and 1/4 cutters so what should I start with for feed and rpm? Also since you guys mentioned plunging thats another good question I was wondering about. How fast should I plunge down and what depth per pass can I get away while still preserving my machines life?



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    Most of the builders are using routers, and a speed control on a router doesn't really work that well.
    So you are running the router at full speed what kind of bits would be advisable then to cut Aluminun, hardwoods and MDF?
    Thanks



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    Quote Originally Posted by fpworks View Post
    Of course, I'm talking about production, which is a LOT different than your approach as a toolmaker. !
    i'm by no means at toolmaker ,thats an art of it's own

    ive worked a fair bit of production work in the past and i learned a lot about speed ,ive knocked so much time off of the jobs we used to run , i'd have been far too bored otherwise .
    on the other hand ive learned how and when to play it safe , where i'm at now we do a wide range of parts with a wide range of material ,and it seems everything is getting bigger every week ,everyday is a learning experience and i'd be lying if i said it isn't a challenging 8 hrs i spend in a day ,when one of the guys approach me with blood shot eyes they don t even need to tell me something bad has happened ,it's written all over their face ,ive learned to try to forsee trouble before the part even goes on the machine , thats where i need to balance how hard we need to push on the job and when to lay off and let the guy be to consentrate and get the job off ok

    Quote Originally Posted by fpworks View Post
    Rev02: 3 flute Data Flute ALDH, 250-500 ipm

    Shows importance of tool geometry as well!
    those are beautiful tools , those and cgs are wicked



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    Quote Originally Posted by DerHammer View Post
    great info here guys. I guess I forgot to mention some critical data with my question. My spindle is slow compared to what you guys are dealing with, Its capable of about 3600 RPM. I'm not sure exactly how fast my machine can feed but I'm guessing its around 150 IPM. Its also 40 taper and I have a 5 hp spindle. Machine all together weights about 4000 lbs. Has an older Fanuc OM controller on it.

    So, since I'm using HSS cutters. stick with the 2 flute then for this job. Again I'm using 1/2 and 1/4 cutters so what should I start with for feed and rpm? Also since you guys mentioned plunging thats another good question I was wondering about. How fast should I plunge down and what depth per pass can I get away while still preserving my machines life?
    hard to judge what to recommend without understanding the part or how its being held
    assuming it's a typical application i'd say run it to the max rpm

    ive read somewhere that it takes roughly 1 hp to turn the spindle every 1000 rpm , so your going to want to take it easy on the spindle load



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    Quote Originally Posted by dertsap View Post

    those are beautiful tools , those and cgs are wicked
    Haven't tried on of those yet. I'll give 'em a look. Maybe I can go faster


    DerHammer,
    Dertsap is right...feed/speed for a tool highly depends on the workholding and part geometry. If you have a drawing, that would help. At least provide axial and radial depth of cut, and whether you are pocketing or contouring. (profiling)

    As for power, you're not going to run out of horsepower unless you are facemilling or using fairly large tools (not enough rpm). I initially plan for 0.3 hp per cubic inch of aluminum removed, but most often the tool will be your limit in terms of how much material you remove.



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newb talk, 2 flute vs 4 flute cutters

newb talk, 2 flute vs 4 flute cutters