Machining carbide?!

[Music] hey welcome back today I want to do some carbide machining not machining something with carbide but machining carbide with something these are two old carbide end mills that have their shank reduced in diameter back here this is Joe there's just R&T and me me fooling around and this is not ground this is turned on my leaf with a cbn insert but hey man you can't machine carbide in the Hobby machine oh yeah you can so to give you a little bit of context carbide machining is nothing new or it is relatively new but it's it's it's getting more and more common at work we do some some carbide machining we drill and thread mill into carbide on we have a we have a pretty high-end milling machine for our German manufacturer and we do talk about machining on that whiffed diamond killed it tooling it works really well the threats we get out of it look really crazy good like like a ground finish and if you go on the internet and look up current Kadim normal the common common knowledge is that you use diamonds or diamond coated carbide on machining carbide because it's harder and the carbide but CBN cubic boron nitride is also harder than carbide it's way softer than diamond but it's still harder than than carbide and to be honest I didn't believe that you can machine carbide that way I even wrote one or two one day ago on a German forum that CBN is too soft to cut carbide but then somebody proved me wrong he showed he showed a also a shank of carbide end mill and he was able to make some scratches into it was burn was the cbn insert let's say it that way didn't look didn't look awesome but the insert he used was badly chipped so I went in the shop I took a CBN insert I I read round it as I usually do without an edge prep so it has a sharp edge sharp cutting edge and I did some test cuts and lo and behold it works doesn't hold up very long and the Cobra dust is nasty as can be order the carbide chips in this case but it works so let's go to the Machine and and do some some carbide machining a CBN insert carbide end mill shank of a carbide end mill if you want to look it up it's a twenty20 370 on on and the hoffman group online shop so it's really a solid carbide end mill running a thousand RPM and the feed of 0.03 millimetres thirty microns per revolution so let's see and we're not going to take the interrupted cut that's bad enough on Hart turning but on machining carbide I'm not sure depth of cut is 0.1 millimeter diameter reductions 0.1 millimeter depth of cut this point oh five fifty microns [Music] [Music] [Music] okay first cut finish doesn't look too shabby the sound cuts through this the the cut sounds really nice it's really impressive now let's go down to nine point eight and now I will just go down in 0.1 millimeter diameter increments until I see that the insert is not taking a cut anymore and then multiply the number of cups I took by the length of cut this is thirteen millimeter then I get idear how well or how long does insert less [Music] okay I took I thought I took ten cuts at one mill Madame direction we should be down to roughly nine millimeter which I doubt because we're and to pressure so let's check the diameter yeah it's 9.2 and I can can see on DRO by the deflection I get in there and the kind cross slide that the insert is getting dollar and dollar so let's try a little bit deeper depth of cut without regretting the insert while we're busting this one up we can do it properly - let's take a depth of cutter 15 150 microns that's 0.3 millimeters in diameter and by the way during the machining I wear a dust mask and later I will have to take the Chuck here apart because when I started I didn't think about it and now I got the carbide dust in it all over the place the ways of the lave are covered and also the cross slide is completely covered but I still added some shop towel to catch most of the carbide chips down here and yes it's chips I will I will take some over to the microscope later and show you I think point three millimeter diameter reduction is really pushing it on my machine I can hear the the insert squeak a little bit and I think that's the limit yeah it cuts but it's not happy doesn't doesn't really could also be the insert that's gone now what I really wanted to show that you can actually machine carbide with cbn as you just have seen at work we drill and thread mill into solid carbide but those tools are diamond coded cbn is considered softer than diamonds but it's it's still barely taking a cut in in this material but definitely doesn't last as long as a diamond tool but still we get out of a diamond cut at drill and shrapnel we get about 15 holes in carbide before they show where and the thread is not now gauge fit anymore so let's take this end mill out of the chuck as you can see it's really an end mill and put a shine on the shank you can tell that it's a carbide end mill and I'll supply the way it fractured on the end here when I crashed it so yes this is carbide and no the shank material and the cutting portion honest on a carbide aminal that small is not different material they are ground from one chunk of carbide so I took ten cups on this OD with 50 micron depth of cut length of cut is 13 millimeters so we we cut the length in total of about 100 thirty millimeters before the in third didn't really cut that well anymore I'm not sure if if that's good or bad but it's at least an idea how long did certain will last when you cut something nasty like like carbide and yes when I say carbide I mean sintered tungsten carbide of course so yeah that's that's the idea I just want to see how long it lasts and the kind of where we get on the insert we'll get to that in a second when we look under the microscope so that's that's this let's look at the surface here on a microscope and into chips and the insert we're under the microscope at about 10x magnification here is the silica ground or simplest ground diameter of the end mil you still can see laser engraving on here and here our surface finish I get from turning with CBN insert on an AAMCO hobby lathe the turn surface is of course significant worse than a proper sentence ground surface especially these two shanks have an exceptional good finish but still you can see that the finish is not terrible bad what's bad is the chipping here on the corner that's when I came in with the of the tool then I pulled out like you would normally do when you machined steel to clean up the facer and in that moment it chipped I think that's about my theory or chipped already when I took the cut in here that's something a CNC machine could do way more controlled it could do a nice lead out or a radius at what or whatever to prevent this crazy shipping here and out here you see my attempt at a bigger depth of cut which also worked but I didn't feel like pushing my machine too much the fill carbide so let's zoom in a little bit and take a closer look at the finish here that's about 40 times the magnification and my wooden poker here is very big you see a large large large number of vertical lines which are all all basically the same distance to each other and that's our feet per revolution that we ran the machine at each line is 30 microns to a next line and that's how does this finish gets about but you can also see this it has a lot of tiny speckles or dots in it that's all my to me it looks like a little bit like like cast iron on the microscope like a piece of carbide get broken out of the other other of the matrix of small particle that's that's viewed together to be carbide and I guess that's what we're seeing here those those tiny tiny speckles this microscope doesn't do more than 40 X I I would need more magnification to say more but that's my theory on the ground finish that's the ground finish here we don't get that there is the chip area there is back to the turns turn finish does this look like dust to you this is that 10x without magnification to the naked eye it looks like dust under the microscope not so much anymore let's go to 40 X you can say what you want to me to me these are tiny chips they are they look like a like a miniature cast iron ship basically it's really crazy and yes they are magnetic a little bit magnetic I'm not sure where that comes from carbide is magnetic but way less than steel over here yeah there is a big one so yes it makes chips here is the CBN insert this large area that's missing here that's where I reground the sensor numerous times the cutting edge down he is really down here but you can see that there is a tiny chip and when we sue me and that's the tip of the CBN insert and you see that it's fractured it's really it has lost a lot of its shape one reason might be that I recount this in sort of a fairly coarse diamond wheel you can see the grinding marks going from left to right or right a right to left and those are like tiny stress risers because they are so coarse this was done with a be 125 diamond wheel that probably helps chance of fracturing this the CBN a lot this is not what this is not classic where where the material is operated away this has really chipped away so I'm not sure what to take from this yeah I will just leave I will just leave this here like it is that said thank you all for watching I hope you not sure if you really should learn something from this video I hope you enjoyed thank you all for watching and see you next time [Music]

Channel: Stefan Gotteswinter

Views: 58,945

Rating: 4.9685168 out of 5

Keywords: tungsten carbide, carbide, machining carbide, hartmetall, hartmetallbearbeitung, cbn, cubisches bornitrid, hartdrehen, hartbearbeitung

Id: LxvVUvUBqag

Length: 17min 18sec (1038 seconds)

Published: Sat Sep 28 2019