Endmill Basics

hi everyone today I'd like to talk a bit about n mill basics and what goes into choosing the correct ed mill for the job now there's a lot of variables here it's whether you need to plunge into the work whether you're working on the outside whether you're cutting a pocket or a slot and I'm going to talk about all of those things first of all though let's talk about center cutting versus non center cutting end mills so this is a two flute center cutting end mill and what that means is the flutes go all the way to the middle so if you wanted to you could plunge into the work and you'd get a chip all the way across and you wouldn't jam up the end mill now they have non Center cutting end mills too that have this center hole in the middle from when it was ground what this means is if you were to plunge straight in with this you would actually get this buildup of material this little nub that's not getting cut away and eventually the end mill just wouldn't go any further and burn up and it would it would get destroyed if you need to plunge with your end mill and the only thing you have is a non Center cutting end mill you need to drill a pilot hole first now on CNC machines these are used a lot because CNC machines allow you to do what's called ramping in which case it ramps in this way and then ramps in that way and it's never really plunging all that deep or they'll do the spiral thing and they ramped slowly in with the end mill well let's talk about the flutes as well generally when you've got two flutes this is where you need maximum chip clearance so if you were cutting a slot or a pocket you would at least want to start it out with a two flute end mill because you've got all this room inside the flutes for the chips to go chip evacuation is key because if you can't get the chips out then all you're doing is building up heat and heat destroys the tool so whether you're using a vacuum or compressed air or flood coolant or something you've got to be able to get those those chips out of the end mill or out of the slot in order to keep it from destroying itself generally two flute end mills do not get that great a surface finish because as it sweeps along it cuts this chip and then there's this dead space where the end middle is not even touching the piece and then the other one hits and does the exact same thing so there's a lot of hammering and flexing back and forth you generally just don't get good surface finishes with two fluid n Mills but they give you all the chip clearance you need for cutting slots and pockets if surface finishes a big concern then you would rough it in with a - flute and then follow it up with a for flute and and go through and you would get a much better surface finish now for flutes got better surface finish because as one is leaving the work the next one's entering so there's less hammering and less tool flex and of course there's a lot more material right here so the tools not going to want to flex as much anyway the problem is there's nowhere near as much chip clearance inside the flutes which means that if you're trying to cut a pocket or a slot with it the chips can jam up easier and of course there's going to be more heat now there's a compromise between those two that I don't actually have an example of here but they have three fluted end mills they've got almost as much chip clearance as a - flute but since you've got that extra bit of material you've got a good bit of strength left you see those used a lot in aluminum because you've got the chip clearance you need for it because aluminum likes to really stick to everything but then you've got the added strength and that extra flute gives you a little bit better surface finish now generally when you get into the larger end mills especially larger high speed steel at mills you might have six flutes or eight flutes I don't have a whole lot of larger end mills in my shop so I can't show you one of those either that's so you have more cutting edges and if you look at my feed rate video you can actually feed at a same speed with the slower rpms that you would have with the larger end mill plus it gives you a lot more strength and all the usual things if you've spent any time at all looking at catalogs you'd know that n mils come in a lot of different shapes as well your average everyday end mill is what's called a square end mill you've got a sharp corner right there but my fingernail and it's going to create a square pocket on the bottom with a square bottom toll you also have ball end mills which the shape kind of explains itself here and this is a center cutting ball end mill and these are used for cutting half round pockets of course for pockets with rounded sides and for contouring on CNC machines so all these really fancy videos that you see where you've got some neat organic shape that's done with a ball end mil because it can cut anywhere on the surface and kind of the sweet spot is right around there so that's where they want to do most of their cutting so that's where a 4 and a 5 axis machine comes into play because it can tilt the spindle and it can keep the ball end mil in that sweet spot for manual machines we mostly just use these for light contouring and pockets and cutting the occasional half round groove roughing end mills are pretty awesome if you haven't used these sometimes they're called corncob end mills for just because of the shape but what they're used for is for just removing a ton of material and all these little serrations that you see each one is going to remove a chip and it's a much smaller chip than you would normally get normally if you were cutting along the side you would get this long needle-like chip and this is just going to produce a bunch of tiny chips that are easily managed and easily flushed away so if you're removing a lot of material from the outside or the inside of the part a roughing end mill is a fantastic way to do it the thing with roughing end mills is they produce a lot more friction because of all of this surface area that's in contact with your park so you've got to do something to keep them cool you've got to evacuate the chips and preferably use some kind of coolant or mist or something like that flood coolant mist coolant cutting oil something like that that's going to actually cool the tool in addition to evacuating the chips and one other thing about roughing end mills is that they are for roughing only they're not going to leave a very good surface finish with all these serrations these do not get staggered very much so the surface ends up having a little corncob looking shape it's not as rough as this but it's not something that you would want to hand to a customer and say here's your finished part so he would go in and do all of your roughing with this and then you'd follow it up with a standard end mill and get a nice surface finish on the outside another type that you see pretty often is called a corner radius ten mill or you see these called bull nose end mills sometimes in the catalog and it's an otherwise square end mill but it's got a radiused corner on the tip hopefully you guys can see that on camera so for one thing this makes the end will last a little bit longer it acts the same way as a square one but you don't have that sharp corner that's going to get broken away from the impact of cutting also if you were cutting a pocket with these it would leave a little radiused corner in the bottom of the pocket which means that you don't have a stress riser there that could cause the part to fail now you can get these with various radii on the corners and it's not necessarily size specific so if you're your print calls for a pocket with a sixteenth radius in the corner you can find one that has a sixteenth radius and various sizes now that radius corner end mill the bull nose end mill is not to be confused with one of these guys which is a corner radius and end mill and this is going to produce a radius on the outside corner of a park so if you were to run it along the corner of this part it would produce this radius on the edge you can start out with a pretty heavy cut because you're removing a lot of material that's that doesn't matter it's not going to exist at the end but because of all this contact that you're going to have at the end of the cut you really need to actually take a very very light cut on the last one in order to get a good surface finish otherwise the surface just looks like it's torn and destroyed now the last one I'm going to talk about our tapered end mills these don't get used very much in the home shop or in most shops really they're pretty much a tool-and-die thing so these would be used for producing draft clearance on a die you would go in you'd machine a pocket and if it was something that was going to get deep drawn or maybe a punch you need a little bit of clearance there so that whatever gets punched through will just drop out the bottom of the punch instead of getting jammed up in this square slot likewise if you're doing any kind of drawing if you have a little bit of draft when you punch this thing in and you make your pot or pan or whatever it is the two dies don't get stuck together when they release they just come right out because of the taper these get sold in a lot of different tapers a lot of different angles and you can buy them depending on what you need they are a lot more expensive than regular end mills just because they don't make nearly as many of these as they do these guys so if you need a tapered end mill prepare for some sticker shock I hope this clears up any questions that you may have had about end mills and their different types and hopefully it'll help you choose the right end mill in the future thanks for watching and I'll see you next time

Channel: Stuart de Haro

Views: 151,564

Rating: 4.9355931 out of 5

Keywords: Machining, Machine Shop, Machinist, Milling Machine, Machine tools, endmills, endmill

Id: Y9Qi29WqOCs

Length: 10min 7sec (607 seconds)

Published: Sun Nov 26 2017

Reddit Comments

[u/grauenwolf]

Amazon has those tapered end mills pretty cheap. I'm going to try one for the molds I'm making.