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View Full Version : More fun with Cermets: Hard turning **FIRE**



Evan
07-09-2009, 08:57 AM
I was hard turning a bearing race to make a one way clutch. It looked so cool I took some video as well as stills.

http://ixian.ca/pics6/cermetfun1.jpg

http://ixian.ca/pics6/cermetfun2.jpg

http://ixian.ca/pics6/cermetfun3.jpg

http://ixian.ca/pics6/cermetfun4.jpg

Video in WMV format, 5.5 mb, 1 minute, good quality.

http://ixian.ca/server/cermetfun.wmv

crancshafter
07-09-2009, 09:28 AM
Hi Evan
Nice video. "Oneway clutch" Please make a thread of how to make one.
You see I'm in need for one in the near future.

Regards
CS

Evan
07-09-2009, 09:40 AM
When it is finished I will post about it. Maybe tonight or tomorrow. I am currently working on about four things at once.

Michael Edwards
07-09-2009, 09:42 AM
Cool pics, can't wait to see the video.

ME



Edit: Ya the video was even better. Look forward to hearing the rest of the story.

Peter.
07-09-2009, 02:58 PM
Hi Evan
Nice video. "Oneway clutch" Please make a thread of how to make one.
You see I'm in need for one in the near future.

Regards
CS

Many bike starter clutches are made by spring-loading rollers on a very shallow slope pressing against the inside of a hard drum. Turn the drum one way and the rollers slide back up the slope, turn it the other and they are caught by the drum against the shallow 'taper'. They are very long lasting so long as they are kept well oiled. The same would work on a hardened shaft.

quasi
07-09-2009, 06:19 PM
I was thinking you have the quietest SB 9" geartrain in the world, then I remember you have a d.c. drive on the tailstock end of your leadscrew.

Evan
07-09-2009, 07:24 PM
That was the little "click" and the quiet hum of thw PWM drive.


Many bike starter clutches are made by spring-loading rollers on a very shallow slope pressing against the inside of a hard drum.

Exactly. Except that you don't need the springs if you lubricate it with 3M traction oil. Traction oil lubricates very well for rolling contact but is very difficult to shear and does not permit sliding contact. It was developed for CVTs. It is also perfect for these clutches. I'm using some rollers from a roller bearing that was sacrificed to make a couple of these. 7 rollers per clutch with the ramps ground in the inner race. I've made these before and you need about .010 to .020 negative clearance (interference) between the OD of the inner race and the ID of the outer race. Uaually the ramps should be deep enough that the roller is stopped by a vertical face that meets it at the the midline. I'm experimenting with a slightly different design so I'm not quite sure how well it will work.

exkenna
07-09-2009, 08:33 PM
Hi Evan.

Are you sure it was cermet and not ceramic?

Not trying to be critical, just curious. ;)

Fasttrack
07-09-2009, 09:01 PM
Why do you need a one-way clutch?

I've been thinking about trying some hard turning. My K&T 2D has a proprietary taper - well the taper is NST 20 but it has a proprietary method of holding the taper in the socket because there is no drawbar. It is very hard to find the collets that go with it and I was thinking about ordering a ER32 collet chuck with a straight shank and then machining it to fit the taper.

This would require a significant amount of material removal and (obviously) I would want to test out my taper on a piece of scrap before cutting the taper on the actual chuck. Anyhow, what do you think about trying to remove such a large quantity of hardened material? My gut tells me it won't work too well, but the chuck I was going to sacrafice can be had from the import dealer for 14 bucks... :D

I've got some different carbide inserts, but I've also got 4 Kylon ceramic inserts. I was thinking about using the ceramic...


<edit> ExKenna - I expect Evan did mean "cermet" not "ceramic". They are two different materials. The cermet is a CERamic and METalic composition. They are supposed to be tougher (i.e. less likely to chip or break) than ceramic but be harder and have better high-heat hardness than tool steels.

<edited for ridiculous brain fart>

Evan
07-09-2009, 10:06 PM
It's a cermet insert from Kyocera.

http://ixian.ca/pics6/cermet.jpg

Evan
07-09-2009, 10:18 PM
Fasttrack,

I think it will take a very long time and cost several inserts. However, I doubt that the material is hardened very deep. It is probably induction hardened and that doesn't extend throughout the material, maybe .1 to .2 inch or so and then becoming softer.

The one way clutches are for my hybrid trike. I have started work on it and will be posting about it fairly soon. I already have 2-3 kilowatt hours worth of battery power for it and a small brand new moped engine with about 1.5 kw output as well. Either or both power plants can run at once and the gas engine will recharge the batteries as needed. In town I will use only electric but for the hills I will use both. The main problem I have here is that a trip to town and back requires a total altitude gain of half a mile. You don't get much back through regeneration on the downhill sides. It's a good example of where a pure electric vehicle just won't make the grade, literally.

exkenna
07-10-2009, 01:43 AM
First, my apologies to Evan. The purpose of my question was not to imply that you are ignorant of modern cutting tool technology, or even to hijack your thread. What has piqued my interest is your success hard turning with a cermet. White or black alumina ceramic products are typically chosen for hard turning apps. I can't find any reference to a grade in your posts but I suspect you are using Kyocera's TC30 which is a P05-P10 / K01-K10 grade not specifically intended for hard turning. The high hardness of this grade allowed this in your case but I suspect tool life would be unacceptable in a production environment. A65 or A66N would be a better choice as they are classified as H01-H10 grades for hardened materials.

I realize this may sound like splitting hairs but there is a lot curiosity about cermets. And a lot of misinformation.

Only recently have they overcome their tarnished reputation earned in the '70s, '80s, and early '90s. Dry machining was a new thing and early grades were prone to sudden and catastrophic failure. They became known as hard, brittle tools good only for finishing with light cuts. This has changed and the Japanese have led the way with progressively tougher grades that are becoming more and more accepted. We were so far behind at that time that almost all of our cermet/ceramics were bought under the table from Toshiba Tungaloy and NTK Ceramics and re-branded in the yellow and black packaging everyone recognizes. There have also been real quantum leaps such as Greenleaf's WG300 whisker reinforced product which turned this entire market niche on it's head. Think "fiberglass" for cutting tools.
One day I'll be able to share it's story: an improbable combination of ceramics, rice hulls, and the U.S Navy. ;)

The Kyon grades are another story, be careful to do your research before using these. Pure ceramics and silicon nitrides are very application specific and just because it says "Kyon" doesn't mean it's suitable for hard turning steel. I have an interesting video of a test I ran milling Inconel at 1300 sfm. It looked like someone welding with the end of the spindle :D The part was an exhaust manifold for the Abrams tank.

Where was I ... Oh yeah, cermets.
Cermets are an answer to a question that no has asked yet. Their biggest selling point is a low affinity for carbon steels (eliminating BUE) which allows them to impart a beautiful finish approaching that of a ground part.
You can sometimes improve cycle time using them where a higher sfm is permitted but higher feed is not. This second advantage may be rapidly disappearing with the advent of carbide grades like Sandvik's 4205 (featuring Walter's PVD Al03 technology) which can run low carbon steels at 1200 sfm, with excellent tool life.

Be careful when touting them as "tougher than carbide". A quick glance at a few cermet grades will tell you that hardly any of them exceed P20, M20 or K10 on the ISO chart. The largest part of the carbide market is the P20-P30 range with the toughest grades extending all the way to P45.

Sorry for the long winded reply but I wanted you guys to understand the factors involved before rushing into this realm. Although Evan was successful using a cermet, ceramic is your first choice. You are plasticizing metal through the use of extremely brittle cutting tools in negative rake tool holders at very high surface footages. Rigidity of set-up and proper safety precautions are mandatory.

Evan
07-10-2009, 02:06 AM
I don't know if you saw my previous thread about these particular inserts but it was about the amazingly good finish these produce on low grade steel. One nice feature about these specific cutters is that there are 8 usable corners.

I have no illusions about what these can and cannot do and these aren't the first "exotic" cutting tools I have used. I have ceramic, PCD, and coated carbide inserts, solid carbide sticks 3 inches long, and a large selection of CBN and diamond grinding wheels.

When I find something new in this sort of cutting tool I usually push at least one sample to destruction to find out where the limits are. I will try them on the difficult to machine items such as abrasion resistant steel, hardened items of various alloys and torture tests with interrupted cuts in chilled cast iron.

I am always exploring new materials and ways to machine them. Right now I am looking for a way to machine a hole in C1 carbide. I don't have EDM (yet) but I do have a couple of grades of loose diamond grit.

exkenna
07-10-2009, 02:25 AM
No Evan, I didn't see the previous post. I will search it out as I have been a cutting tool geek for 17 years or so and I like to see people experiment and make tools work to their advantage.

Those were nice pics, thanks for sharing.
If you like homemade videos here's one I shot a couple months ago during an end mill test.
If you get bored skip ahead to the 2:45 mark.

http://www.youtube.com/exkenna#play/uploads/3/_iVRrFKNtBU

dp
07-10-2009, 02:33 AM
What were you cutting and what were you cutting it with? That's a pretty impressive doc and feed speed.

exkenna
07-10-2009, 02:35 AM
It was a 1/2" 5-flute carbide end mill cutting 4130.

dp
07-10-2009, 02:55 AM
Dayum - I feel like I'm doing good with 0.010 and crawling through 1018 with my rig. I'm going to have to try pushing it a bit harder. I'm obviously new at this stuff.

Recall the spindle RPM?

exkenna
07-10-2009, 03:07 AM
3800 RPM.

All the cut data is in the credits at the start of the vid.
To be fair, this was a 12,000 lb Doosan 40-taper machine.
It's a video I made for some guys on PM but if you're like me, you love seeing cutters mow metal regardless of who's they are :D .

I had better shut up, you guys are gonna ban me for hijacking Evan's thread.

oldtiffie
07-10-2009, 03:50 AM
Keep going exkenna - so far as I can see, you are right on topic.

I am amazed at what Even is doing as well - the more so with a belt-driven SB lathe - and that is NOT "rubbishing" SB or American machines - quite the opposite in fact.

There are many here with SB's or better that now have the power and the tools to machine stuff that up 'til now was or was considered to be impractical or impossible.

Its all part of the "useful knowledge" scene.

I will be surprised if it didn't get Evan's attention, and that being the case, I would guess that he would not mind the new info which is neither a "hi-jack" nor is it OT.

Evan
07-10-2009, 04:30 AM
That is very impressive. I am uploading a video right now of my CNC mill doing a bit of high speed machining. Nothing like that but then it also doesn't weigh 6 tons. :D

Carbide end mills are my favorite too. That reminds me, I need to place an order for some more.
Give it about 20 minutes from the time this is posted and then check out

http://ixian.ca/video/banshee.wmv

It's about 14 MB and I will be removing it after a day or so to prevent excess server load since items like this are picked up by Google within 30 minutes on this forum.

jackary
07-10-2009, 07:04 AM
Evan,
That spindle of yours is very impressive. Thanks for showing it
Alan

clutch
07-10-2009, 10:20 AM
Lots of tool porn in the morn. :D

Interesting pictures of your cnc machine. Copper chip guard on the lathe? Adds to the color of the picture for sure.

Welcome Exkenna, I have read your posts over at PM many times. Hope you didn't mention a chinese insert over there and get booted :rolleyes:

Clutch

Evan
07-10-2009, 11:25 AM
That is really an aluminum chip guard. That job was throwing great flaming balls of fire across the shop. You might also notice a tinge of red in some of my lathe photos. That is a 40 watt red light bullb that reminds me to shut off the power to the axis drives.

Fasttrack
07-10-2009, 12:41 PM
ExKenna - I'd love to see the video of the inconel action! (you should post a thread about it!) I know nothing about all these new fangled cutting materials. All of my machines are WWII vintage and I stick primarily to HSS. Which works great for what I do, and it's cheap since I have more time than money :)

But I got this Kyon for free and I don't really know what to use it for. I thought it might be worth trying...

Michael Moore
07-10-2009, 02:45 PM
The red-hot glowing swarf is pretty exciting, isn't it? I've turned and parted off Thomson shaft with standard carbide inserts that I got from Curtis (exkenna) and the surface finish seemed pretty nice.

http://www.eurospares.com/graphics/Bultaco/SherpaTswingarm05.jpg

You can zoom in on the reduced end of the new bushing which is still in the surface hardening on the shaft. I was very pleased with the smooth surface.

cheers,
Michael

lazlo
07-13-2009, 03:47 PM
ExKenna - I expect Evan did mean "cermet" not "ceramic". They are two different materials. The cermet is a CERamic and METalic composition. They are supposed to be tougher (i.e. less likely to chip or break) than carbide but be harder and have better high-heat hardness than tool steels.

I was curious when you posted this, because Cermets have a reputation of being fragile inserts used primarily for finishing operations.
According to this article from Cutting Tool Design, carbide is a lot tougher than Cermets. They're measuring carbide insert rupture strength 2 = 8 times greater than cermets:

Ceramics Take a Turn: Improving Turning Productivity with Ceramic Inserts

http://www.cuttingtoolengineering.com/dynamic.articles.php?id=255

Toughened Up

There’s no question that a carbide insert is tougher than a ceramic one.

Transverse-rupture strength, the stress required to break a specimen, is commonly used to measure insert toughness. A typical carbide insert has a TRS ranging from 250,000 to 450,000 psi. This compares to silicon-nitride at 180,000 psi, aluminum-oxide/titanium-carbide at about 110,000 psi and pure aluminum oxide at roughly 60,000 psi.

Fasttrack
07-13-2009, 04:01 PM
I was curious when you posted this, because Cermets have a reputation of being fragile inserts used primarily for finishing operations.
According to this article from Cutting Tool Design, carbide is a lot tougher than Cermets. They're measuring carbide insert rupture strength 2 = 8 times greater than cermets:

Ceramics Take a Turn: Improving Turning Productivity with Ceramic Inserts

http://www.cuttingtoolengineering.com/dynamic.articles.php?id=255

Toughened Up

There’s no question that a carbide insert is tougher than a ceramic one.

Transverse-rupture strength, the stress required to break a specimen, is commonly used to measure insert toughness. A typical carbide insert has a TRS ranging from 250,000 to 450,000 psi. This compares to silicon-nitride at 180,000 psi, aluminum-oxide/titanium-carbide at about 110,000 psi and pure aluminum oxide at roughly 60,000 psi.


Oops - that was my bad, Lazlo. What I meant to say was that Cermets are tougher than Ceramics, not carbide. They are supposed to have better high heat hardness and over all hardness than HSS or carbide but be tougher (in general) than ordinary ceramic.

I didn't even catch my error after reading ExKenna's post!

<edit> Agh! I did it again in this post! My hands just keep wanting to type carbide instead of ceramic. :o

Evan
07-13-2009, 04:04 PM
This particular insert is pretty tough. A lot of carbide inserts won't do what it will. I used it to turn down a hardened bike sprocket on my moped and it did just fine without damage even with the interrupted cut.

http://ixian.ca/pics6/moped2.jpg

lazlo
07-13-2009, 04:05 PM
What I meant to say was that Cermets is tougher than Ceramics, not carbide.

Oh, now I'm really confused. :o My understanding of Cermets is that it's a ceramic metal, typically silicon nitride or a carbide mixed with a carrier like aluminum oxide. Is there such thing as a pure ceramic insert?

I've never used a cermet because Moltrecht et al describe them as fragile inserts used for specialty finishing operations. But Evan and Glenn are showing some amazing results. That article I posted was from 2000, and the Machine Design article about cermets I posted in the other thread indicated that micrograin cermets are way tougher...

Evan
07-13-2009, 04:11 PM
I used another grade of silicon nitride Cermet in the fly cutter on my mill. It worked beatifully until I accidentally ran it into a hardened steel edge with a much too deep DOC. Even then it just nicked the cutting edge. My experience with Cermets is limited but so far they seem tougher than the closest equivalent carbide cutters.

Glenn Wegman
07-13-2009, 04:17 PM
lazlo,

You need to step over to the dark side for a day and try one!

I'm not a reader, I have more fun figuring out a way to make inserts work in different materials by noodling with speed and feed. If you are running production, it is a different thing as you are looking for a balance of efficiency, finish, and longevity, so specialized insert configuration is a must.

If you were running a production job with an interrupted cut a Cermet may not be the optimum choice, but for limited use, it will probably live just as well as anything, as Evan's sprocket or my hardened shaft exercise.

Glenn

pcarpenter
07-13-2009, 04:39 PM
Oh, now I'm really confused. :o My understanding of Cermets is that it's a ceramic metal, typically silicon nitride or a carbide mixed with a carrier like aluminum oxide. Is there such thing as a pure ceramic insert?

I've never used a cermet because Moltrecht et al describe them as fragile inserts used for specialty finishing operations. But Evan and Glenn are showing some amazing results. That article I posted was from 2000, and the Machine Design article about cermets I posted in the other thread indicated that micrograin cermets are way tougher...
Lazlo-- It's easy in a long topic like this to miss something--I found that I had some catching up to do. I think that post #12 from Exkenna sort of clears this up....apparently the durabilities of inserts containing ceramics have much improved such that Moltrecht's info may be a bit dated. He goes on to say they are not as tough as the toughest carbides, but are far better than they used to be and that some recent advances in strengthening have made this possible.

He also seems to suggest that there are some differences between cermets and other ceramic inserts such that the two are not interchangable terms. Maybe he can clarify further.

Paul

Fasttrack
07-13-2009, 04:44 PM
Oh, now I'm really confused. :o My understanding of Cermets is that it's a ceramic metal, typically silicon nitride or a carbide mixed with a carrier like aluminum oxide. Is there such thing as a pure ceramic insert?

I've never used a cermet because Moltrecht et al describe them as fragile inserts used for specialty finishing operations. But Evan and Glenn are showing some amazing results. That article I posted was from 2000, and the Machine Design article about cermets I posted in the other thread indicated that micrograin cermets are way tougher...

Well, like I said, I have very limited expierence with carbide/ceramic/cermet cutting tools as I prefer HSS. But I assume that there is a difference between ceramic and cermet inserts. There is certainly a difference if you ask a material scientist or ceramic engineer.

I believe that the ceramic inserts are pure ceramics - i.e. Kyon is pure? silicon nitride. A cermet, OTOH, is a ceramic material and a metal (usually cobalt) binder.

I'm approaching this from a more "scholastic" perspective, so I could be completely wrong as far as cutting inserts go. Hopefully Exkenna will jump in and clear things up... :)

lazlo
07-13-2009, 05:35 PM
Lazlo-- It's easy in a long topic like this to miss something--I found that I had some catching up to do. I think that post #12 from Exkenna sort of clears this up....

Wow, no kidding! Yes, I did miss Exkenna's post, which is excellent.

So apparently there are pure ceramic inserts, as opposed to Cermets. But I'm left scratching my head as to which a HSM'er would want...

If I understand his post correctly, ceramic inserts for hard turning, cermets for finishing. I use plain old carbide (and sometimes CBN) for hard turning, so I'm I'm a lot more interested in the super finishing application of Cermets.


White or black alumina ceramic products are typically chosen for hard turning apps.

Cermets ... biggest selling point is a low affinity for carbon steels (eliminating BUE) which allows them to impart a beautiful finish approaching that of a ground part.

Although Evan was successful using a cermet, ceramic is your first choice. You are plasticizing metal through the use of extremely brittle cutting tools in negative rake tool holders at very high surface footages. Rigidity of set-up and proper safety precautions are mandatory.

Evan
07-13-2009, 07:28 PM
As usual, there are a range of choices and in this case the cermet seems to be every bit as good as a ceramic and probably tougher. That's most likely just this particular type but it certainly isn't fragile. It's also extremely hard. Bicycle sprockets and related parts are some of the hardest things I have ever machined. I tried some carbide on the sprocket and all it did was rub. In the past I have usually ground the parts instead of trying to turn them. I was rather surprised when the insert cut the sprocket with ease.