I need some recommendations on CCMT inserts

[D.sebens]

MT are usually molded. The GT are often ground to meet the higher tolerance, if I recall correctly. But it's quite possible you have run into a bad lot, or manufacturer. MT's ought to be a bit more rugged. You ought to check out @MrWhoopee 's recommendation, he has found some good stuff. I bought a face cutter based on his recommendation and it's been awesome.

I have also pretty much purchased all my inserts based on his recommendations. I went ahead and ordered a box of both sizes to try.

 

[GeneT45]

I've found an astonishing number of great import inserts recently. I have a pretty good stash of Shars, Hertel and Kennametal CCMT already, so I haven't tried that particular form, but Axolotl.ct and Zouzmin (both via Amazon) have been great in other configurations. My Shars CCMT have been "perfect" so far, but I use them for boring so they don't get nearly enough use for me to say much about them one way of the other.

Also, are you facing from the center out, or from the outside in? Outside in for carbide, every time.

GsT

Edit: brain is faster than fingers...

 

[D.sebens]

I've found an astonishing number of great import inserts recently. I have a pretty good stash of Shars, Hertel and Kennametal CCMT already, so I haven't tried that particular form, but Axolotl.ct and Zouzmin (both via Amazon) have been great in other configurations. My Shars CCMT have been "perfect" so far, but I use them for boring so they don't get nearly enough use for me to say much about them one way of the other.

Also, are you facing from the center out, or from the outside in? Outside in for carbide, every time.

GsT

Edit: brain is faster than fingers...

Outside in. I think it has to do with the flex of the part. When it’s happened there has been a larger ratio of stick out. I also am still working out feed rates with it. It is happier going faster than you would think. I like when I can get that cutting squeal of a strong engaged cut.(not the chatter noise)

 

[G-ManBart]

Outside in. I think it has to do with the flex of the part. When it’s happened there has been a larger ratio of stick out. I also am still working out feed rates with it. It is happier going faster than you would think. I like when I can get that cutting squeal of a strong engaged cut.(not the chatter noise)

I've had similarly outstanding results with the CCMT inserts like the ones Mr. Whoopee posted....they're also sold on eBay with the "Nano Blue" name making them easy to find.

I probably sound like a broken record for saying this frequently, but post a picture of your exact setup when you're having the chipping issue. I say this because so many times people post having problems and when they finally post a picture of their setup it's some whacky combination of tool post/tool position/angle/etc that simply isn't going to work. With a lantern tool post and HSS you can get away with oddball setups, but carbide is less forgiving that way. The tools and inserts are made with the expectation that the tool will be in a specific orientation to the work, and if you deviate, you can run into problems. I'm not saying that's the problem, but it does show up regularly.

 

[D.sebens]

I've had similarly outstanding results with the CCMT inserts like the ones Mr. Whoopee posted....they're also sold on eBay with the "Nano Blue" name making them easy to find.

I probably sound like a broken record for saying this frequently, but post a picture of your exact setup when you're having the chipping issue. I say this because so many times people post having problems and when they finally post a picture of their setup it's some whacky combination of tool post/tool position/angle/etc that simply isn't going to work. With a lantern tool post and HSS you can get away with oddball setups, but carbide is less forgiving that way. The tools and inserts are made with the expectation that the tool will be in a specific orientation to the work, and if you deviate, you can run into problems. I'm not saying that's the problem, but it does show up regularly.

Stock is just for illustration purposes.

 

[Huub Buis]

If you cut from inside to outside using a CCMT type insert, the cutting edge when cutting from inside to outside is much longer resulting in higher cutting forces.
Chatter means the cutting forces are to high for the setup. Either make a more rigid setup (less stock stick out, less tool stick out, less top slide over hang, etc) or reduce cutting forces by reducing depth of cut, reducing feed per revolution, reducing RPM, reducing tool nose radius, use a sharper tool, etc.
If the tool is not on center but to low, facing that last 0.5 mm pip will chip the tool regardless of the setup or turning parameters.

 

[D.sebens]

If you cut from inside to outside using a CCMT type insert, the cutting edge when cutting from inside to outside is much longer resulting in higher cutting forces.
Chatter means the cutting forces are to high for the setup. Either make a more rigid setup (less stock stick out, less tool stick out, less top slide over hang, etc) or reduce cutting forces by reducing depth of cut, reducing feed per revolution, reducing RPM, reducing tool nose radius, use a sharper tool, etc.
If the tool is not on center but to low, facing that last 0.5 mm pip will chip the tool regardless of the setup or turning parameters.

I cut from the outside in. When turning I do have the tool at an angle so the cutting edge isn’t square to the work but if I let it hang at the shoulder it will chatter. These scenarios don’t happen every time. But when they do it always breaks the insert. I’m going to try other inserts as I think these are just very cheap.

 

[WobblyHand]

I cut from the outside in. When turning I do have the tool at an angle so the cutting edge isn’t square to the work but if I let it hang at the shoulder it will chatter. These scenarios don’t happen every time. But when they do it always breaks the insert. I’m going to try other inserts as I think these are just very cheap.

Do you regularly have such a large stick out when you are turning? The picture you posted earlier has a stick out of over 4:1, which can lead to chatter or deflection.

 

[D.sebens]

Do you regularly have such a large stick out when you are turning? The picture you posted earlier has a stick out of over 4:1, which can lead to chatter or deflection.

No. I must of not stated it clear earlier. I just put that stock in there for the picture. If I were turning that it would of had the tail stock.

 

[G-ManBart]

I cut from the outside in. When turning I do have the tool at an angle so the cutting edge isn’t square to the work but if I let it hang at the shoulder it will chatter. These scenarios don’t happen every time. But when they do it always breaks the insert. I’m going to try other inserts as I think these are just very cheap.

The setup you posted looks pretty conventional, so that's good. For the geometry to be correct you want the shank of the tool parallel with the face of the chuck. I use a 123 block against the chuck face, then move the carriage towards the chuck until the tool shank is pressing on the 123 block, then tighten things down. That will give the correct relief angle. Also, make 100% certain the tool is on center. This is for both turning and facing.

Chipping when facing often happens when you get near the center and the surface feet per minute drops to nearly zero, which carbide doesn't like. Unless you're already running really high speeds, I would try going faster when you face. Also, it's a good idea to at least lightly tighten the carriage lock on smaller lathes when making a facing cut.

What sort of RPM are you using when you get the chipping?