TCMT VS CCMT

Just wondering what the pros and cons between these two inserts.

Only thing I can see is one has 3 cutting points and the other 2 but am sure there is more to ut than just that

Not long before 1000 posts

Edited By petro1head on 29/09/2023 11:07:50

With the right holders all 4 corners of a CCMT can be used

The other thing to consider is the available variety of holders for the inserts.

The ones branded Glanze (sold via Chronos) are an example: inter alia, they offer one that uses the normally-unused edges of the CCMT insert, so you obtain four edges out of each insert. Unfortunately, that holder seems specific to Glanze and only available as part of a set.

A seconday consideration is what holders are available for boring.

Did not know that, got a linkbto one please

Examples would be these:-

**LINK**

**LINK**

Basic codes for pin style holders to use the obtuse corners of a CCMT are PCBNL and PCBNR.

More use in theory than practice as the layout makes for a cumbersome tool. I have a PCBNL 2020 which should be good for facing jobs but it's pretty much impossible to get into position for anything else. A PCBNR could, in principle, be used for reducing the diameter of fairly long length of stock but you have to make prior arrangements for the overhang of the tool in front of the cutting point unless its a single, pretty shallow, cut.

In practice you do rather less pure facing than longitudinal turning so an insert in an obtuse holder will last a very long time.

The ordinary CCMT holders are quite capable of handling facing duties anyway. They can cut up to a shoulder too inherently leaving a nice radius for stress relief. So switching tools just for a facing cut tends to be too much trouble. I have about 5 CCMT inserts saved to use up the other corner. I won't live long enough to use them.

Clive

Edited By Clive Foster on 29/09/2023 12:27:52

Plenty of other suppliers other than Glanze, Mine were JB Cutting tools, look for SCBCR and SCBCL such as the ones from APT

Not sure why Clive's one can't easily be used for facing, could be as his are pin location rather than the screw location I have and why my codes start with S for screw .this is mine in action

Edited By JasonB on 29/09/2023 14:15:13

Jason

Mis read my post I think. Mine are OK for facing but thats about all.

Being pin lock on a 20-20 shank for the CCMT 12-04 size inserts I have its all bit cumbersome.

Your smaller inserts and screw lock shanks are vastly more handleable. Doing something like your second picture with my bigger inserts and shank is barely worth the hassle.

Even working 12" to the ft scale.

Which is why I've never bothered to get a right hand holder.

Size really does matter and for the normal model engineer I can see no reason for setting up to use -12- size inserts. Go smaller.

Locking into -12- size over a decade ago because the price was right may have been a mistake on my part although there are no issues with plain turning and the insert in normal configuration.

Clive

Posted by JasonB on 29/09/2023 14:03:57:

Plenty of other suppliers other than Glanze, Mine were JB Cutting tools, look for SCBCR and SCBCL such as the ones from APT

Not sure why Clive's one can't easily be used for facing, could be as his are pin location rather than the screw location I have and why my codes start with S for screw .this is mine in action

Although you get an angled shoulder when turning diameters they still work well for shifting metal, seen here roughing out an EN8 crankshaft and not so cumbersome that you can't use tailstocck support

And a deep cut in aluminium with CCGT using the spare corner

Edited By JasonB on 29/09/2023 14:15:13

So am I correct in thinking I will need two different holders depending on the orientation of the insert

Yes; I start using the acute angle corners and when those are worn/broken I move the insert to the other holder and use the obtuse angle corners.

Andrew

I find I tend to make more or less equal use of both maybe 60/40 in favour of the facing one. So maybe think about getting that first and see how you get on. I find I can more or less keep up with using all my inserts on all four corners having the two options, if it were just for facing then I'd probably start to build up a backlog.

I also find the fact that the other two "unused) corners being over 90deg are a bit more durable so ideal for castings or other irregular work

I use CCMT/CCGT inserts more than 10 years. I use the 2 unused cutting edges of the CCMT/CCGT on my mill for facing jobs.

The CCxT inserts are smaller than the TCxT inserts. That can be a benefit for small diameter internal turning. Due to the 5° cutting edge, on the CCxT inserts, swarf can build up easily and can get between the cutting edge and the part. This results in scratches on the just turned part and dimensions are off. In general, I prefer a TCxT or DCxT insert.
I make the insert holders my self so I can choose the cutting edge angle. I use the TCxT inserts at an angle of 15° for facing and turning.
For the DCxT inserts, you can buy Q type holders (SDQCR07).