Valenite tool holder

[Mike R]

I'm sure others are more expert in this than me, but here is my take - copied and edited from something I shared with a few local club members about buying cheap import carbide for the home shop - bolded is relevant to the question at hand.​

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Insert nomenclature is covered by an ISO standard(metric), and an ANSI standard (inch). Here's my understanding / short explanation of some of the important features to us (i.e. hobby machinists). Be careful – the US ANSI B212 nomenclature is very similar to the ISO one but can cause confusion as what may be a 09 (meaning 9mm) in ISO is 3 for ANSI (meaning 3/8”). I'll stick to the ISO as its what the Asian suppliers tend to use..(no guarantees).

The holder obviously dictates a few parameters of the insert, such as its cutting length (size) and thickness, side clearance angle and shape but we still have a few more items to decide on.
The first letter of the code for the insert is the shape, so match this to the holder. (C,D,R, T or V)
The second letter is the side clearance – again match to the holder (usually C)

Third letter is the “tolerances”. This is one where we get to pick features of the insert that may differ from one insert to another for the same tool holder.

I refer to this as the “finish” of the insert even though its indicated as the tolerance. This has a lot to do with how sharp the cutting edge is.
An insert that is sold / marketed as being for non-ferrous metals or aluminum specifically usually has a very sharp cutting edge and a mirror like finish without any coating. It will almost always be identified with a G in the 3rd letter position of the insert name (ie DCGT CCGT VCGT etc.).
The letter M is often used to designate the insert is “as molded” in the third letter position. This means that the cutting edge has a very slight radius to it, and is usually marketed to be used on ferrous (steel) and the like, and also very often has a coating applied (TiN, or some other PVD coating). In the home shop they are great for steel, but realize that they aren't great for finishing with a very light cut. They prefer a cut of at least some depth due to the less sharp edge.

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To cut to the chase - for an aluminum cutting insert, look for CCGT - the G in the "tolerance" position means "ground" finish and will be very sharp.
One last new caveat - I don't know if the ISO and ANSI inserts are interchangeable - they may not be - i.e. 9mm is not exactly 3/8" - so if you know your holders are made with ISO standards I'd stick to ISO inserts.

 

[Susquatch]

I don't agree with what has been said above. But I am also no expert. I only recently dove into the world of carbide inserts too.

It is my opinion that the nomenclature for both ANSI & ISO do not include information about the material application at all.

The target material is a separate detail on the insert box. Usually a colour or a specific designation on the box. The target material will almost always be written on the box or on the sales information. Often there will also be coating and metalurgic details which are also specific to the target material.

The tolerance has nothing to do with the target material. It is a dimensional tolerance not a sharpness tolerance.

I need to lookup your inserts to figure out if your conversion is correct. I can't remember details like that in my head.

 

[Susquatch]

I believe the corresponding insert to a CCMT09T304 is CCMT32.51.

Regarding tolerance, M is just a tighter tolerance than G. Here is a chart for the various designations. Note that the edge is not included. Just the dimensions.

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The tolerance doesn't mean a hill of beans for us mortals using manual lathes. But it probably does matter to someone using a CNC lathe to produce precision parts. They cannot allow a new insert to cut slightly bigger or smaller parts when they change out a broken insert.

Since M tolerance is tighter, it becomes harder to find what you want. However, you can freely substitute G tolerance inserts on your holder. They will fit just fine.

Here are some CCGT09T304 for Aluminium. Note the little color chart on the box where N is for Aluminium. The BU810 is the insert metalurgy this manufacturer chose to use for their inserts for Aluminium.

https://a.co/d/bc6oedc

 

[ShawnR]

Thank you @Mike R and @Susquatch. Sounds like I had the right ones. I will order some up to add to the collection

 

[ShawnR]

When I google CCGT, they all come back as aluminum cutters (or rather soft material). CCMT comes back as steel cutters. Don't know why the "tolerance" designator seems to reflect the material it is intended for, but what @Mike R says seems to work with that...

Third letter is the “tolerances”. This is one where we get to pick features of the insert that may differ from one insert to another for the same tool holder.

I refer to this as the “finish” of the insert even though its indicated as the tolerance. This has a lot to do with how sharp the cutting edge is.
An insert that is sold / marketed as being for non-ferrous metals or aluminum specifically usually has a very sharp cutting edge and a mirror like finish without any coating. It will almost always be identified with a G in the 3rd letter position of the insert name (ie DCGT CCGT VCGT etc.).
The letter M is often used to designate the insert is “as molded” in the third letter position. This means that the cutting edge has a very slight radius to it, and is usually marketed to be used on ferrous (steel) and the like, and also very often has a coating applied (TiN, or some other PVD coating). In the home shop they are great for steel, but realize that they aren't great for finishing with a very light cut. They prefer a cut of at least some depth due to the less sharp edge.

Thanks
Cheers,

 

[Susquatch]

When I google CCGT, they all come back as aluminum cutters (or rather soft material). CCMT comes back as steel cutters. Don't know why the "tolerance" designator seems to reflect the material it is intended for, but what @Mike R says seems to work with that...

I had no trouble finding CCGT for steel, stainless, and cast iron. But I will say that the majority were for Aluminium.

I'm not sure why that is. It could be that its a supply thing. It might also be that small inserts like those need a bit tighter tolerances for steel than they do for Aluminium.

Anyway, absolutely nothing I found just now suggested that a tighter tolerance is required for Aluminium.

I suppose it's also just a coincidence.

I tried similar searches for other insert styles and found no correlation at all.

Go figure.

I'm gunna do a few more checks to see if my understanding has holes in it. I can always learn something new

 

[Mike R]

It seems that its not common practice to make G tolerance inserts intended for steel or harder to machine materials, leaving fine finishing for grinding etc.
I stand by my post - note though I came at this from a hobbyist perspective buying what is readily available from the cheapest sources. Industry practice may(and likely does) differ.
@Susquatch you are right that G and M do not actually mean Ground or Molded, but in practice this is very typical, as it seems to be to achieve the required tolerance the practical / cost effective method is/was to finish grind, resulting in a sharp edge.

Also, looking at the chart you posted, G only has ±1 thou tolerance (for d and m) versus M having ±2 to ±6 or 8 thou.
Check out MSC description of inserts https://www.mscdirect.com/betterMRO/indexable-turning-tools-guide and Travers - https://solutions.travers.com/metalworking-machining/turning/how-to-identify-indexable-inserts I would not call either company an authority in inserts but generally agree that G is tighter tolerance than M and that G is commonly assumed to mean "Ground" cause it frequently is.

 

[Susquatch]

It seems that its not common practice to make G tolerance inserts intended for steel or harder to machine materials, leaving fine finishing for grinding etc.
I stand by my post - note though I came at this from a hobbyist perspective buying what is readily available from the cheapest sources. Industry practice may(and likely does) differ.

I am a hobbiest too. I have over 40 years experience using a lathe but only just recently started using Inserts to any degree. Quite frankly the nomenclature intimidated me until I dug Into it a bit more. I'm still learning. I'm the kind of character who goes all anal on that stuff and I don't like it when things don't make sense.

@Susquatch you are right that G and M do not actually mean Ground or Molded, but in practice this is very typical, as it seems to be to achieve the required tolerance the practical / cost effective method is/was to finish grind, resulting in a sharp edge.

I've inspected a lot of inserts under high magnification - especially as it relates to sharp vs rounded.

I do see in your reference that the first says "It’s logical to think that the M in CNMG identifies it as a molded (or pressed) insert and the G in VPGR as one that’s been ground to size. And while this might be true in many situations, the M actually signifies the tolerance range—looser, in this case, compared with the more stringent G—used in the insert manufacturing process..... Which implies a lot of people use it to mean that but it's really just tolerance.

Your second reference comes right out and says that G means ground. Go figure!

It makes some sense to me to think that it actually did mean ground edge back in the early days when grinding might have been required, but then as processes improved, and a standard was released, it got changed to mean tolerance only. Who knows? I'm old enough to have been around back in those days but I didn't give a crap back then.

Today, despite what Travers says, I really don't think it is used to mean ground anymore. I searched Iscar, mitsubishi, sandvik and kennametal and couldn't find anything that said anything other than tolerance. I'll bet big bucks that there are both old timers and young machinists who still use G to mean ground though.

Here are some of my inserts for Aluminium that are not G. They are both M Tolerance. But they are also both razor sharp and not ground. I did find one milling insert for Aluminium that was tolerance G and also appeared to be ground. So there's that.



Edit - I went looking for that G insert again and now I can't find it. The one I thought had been G, turned out to have been K. Crap.

Here are some more milling inserts. One for steel, one for Stainless, and one for aluminium. All three are APKT. The one for Aluminium appears to be ground but is not G.



When I buy inserts for Aluminium, I don't pay any attention to the tolerance - no matter what it might mean to some. It has not bitten me yet but never say never. I buy my inserts for the material I plan to use them on and I confess that I use inserts for Aluminium on steel, stainless, and cast iron all the time just because it is sharp and I can take finer cuts. I learned that from others here on our forum.

Whatever the G actually means before and today, I don't think you can or should depend on it today to mean ground, or sharp, or for Aluminium.

Just my opinion.

 

[Mike R]

Maybe the next caveat I need to make is that I buy exclusively from the cheapest source around . (read Aliexpress, followed by Amazon)
That means I need to bring myself to their way of selling / describing things. That means that for most stuff, the sellers have no idea, or can't translate it well, and just put up whatever info they have - usually just the insert code that does not specify materials to be used on. So far searching for "G" has also found me inserts that are rated for aluminum, by luck or by convention, but I happy to continue my searches that way. If I ever get into machining in a serious, paying kind of way I'll have some learning to undo for sure, but for now this works for me.

 

[Susquatch]

Maybe the next caveat I need to make is that I buy exclusively from the cheapest source around . (read Aliexpress, followed by Amazon)

Pretty much applies to me too. Although I tend to use amazon more often than Ali. I get faster replies to questions that way. And unless it is clear, I always ask.

One thing I didn't really think much about in our earlier discussion is the insert style and size. Lots of things get influenced by that.

I don't really use many 1/4" inserts. Most of what I use are bigger inserts because my lathe and tool holders are the next bigger size - but still not the biggest.

I'd hazard a guess that smaller inserts and in particular the C & T style inserts are more likely than others to be named according to your "F"ormed & "G"round characteristics.

Fundamentally, I agree that Ali and Amazon are more likely to be aimed at Hobbiests and less likely to be very rigorous about their terminology.

Nonetheless, I recommend always looking for something that clearly says that they are for Aluminium rather than trusting that G means ground for Aluminium. In some cases it might be right, but it could just as easily be wrong. The ones below are a case in point. They are for Aluminium but the tolerance is M not G.

It's too bad that the target material was never built right into the nomenclature. It's just another letter for Pete sake. In fact, they already have a letter standard everyone uses!

 

[ShawnR]

This breaks the codes down nicely

How to identify Carbide Insert? - Lets Decode the Mystery in 8 Steps.

What are Carbide Insert Grade, Insert Size, Carbide Insert Geometry, Angels, Full forms, Specifications , Dimension summarized in easy and simple way be it turning insert, milling insert, grooving or threading. 8 Step Process to understand any kind of insert.

jaibros.com

 

[Susquatch]

This breaks the codes down nicely

We all have our favorite charts for that. I listed a whole bunch of them in this thread (which was too much work). My thread gives direct links to what each of the major insert manufacturers provides.

Thread 'Links to carbide insert reference documents' https://canadianhobbymetalworkers.com/threads/links-to-carbide-insert-reference-documents.5566/

Please note that the breakdown chart you provided doesn't tell you how to get inserts for Aluminium.....

Personally, I prefer a chart that puts everything on one page that can be posted on the wall behind my lathe.

The ones on Little Machine Shop are available in both ISO and ANSI. They also do a step by step breakdown like your reference.

ANSI and ISO Insert Designations

These charts show the ANSI and ISO designations for turning indexable inserts.

littlemachineshop.com

Last but not least I bought a book by David Best that is very simple but comprehensive. It's a bit expensive but highly recommended. He also gives recommendations.

https://a.co/d/dUQhVLo

 

[lucsimoneau]

Just my little input here for mankind in the realm of inserts - manufacturers will make them to various sizes but one must not mistake the added information pertaining to the grade of the insert, which is a whole other subject, for example, when dealing with tool suppliers like Iscar, the appropriate GRADE of the insert is an Iscar numbering system like IC20 for aluminum, IC806, IC8250 etc ... When using Sandvik inserts they have numbers like GC4025 etc ... I tend to base my information on reputable manufacturers like Iscar, Sandvik, Mitsubishi, Kyocera, just to name a few. These companies also use inhouse identifiers for shape of chip breakers ... here is a good rightup from Sandvik on the subject