What are these numbers?

[Pete O]

The thread cutting chart on my lathe has a set of numbers in each of the chart locations, below the TPI number. I have ignored these numbers in the past as I had no idea what they meant. It occurred to me the other night that they must relate to the travel of the saddle, ?in inches per revolution, when using the geared drive rather than the leadscrew- only thing that makes sense to me. Would that be correct?

   

If that is the case, how (if at all) does that relate to these numbers on a pack of carbide inserts?
These are parting inserts, the only ones I have in a pack (I have a bunch of other mystery inserts from a clearing sale)

   

I know what SFM is, I can deduce that M/min is the direct metric equivalent, I have absolutely no idea what the P15-P30, M20-M30 and K20-K30 refer to.

[Mayhem]

The numbers indicate the characteristics of the material but I'm on my phone now and cannot access my files. Go to the Walter USA site and download one of their catalogs. All the info you need is in there.

Or you should be able to find it on the carbide depot web site.

Use the search page here (not the box at the top) and search for insert posts by PixMan. Especially the one on caring for a carbide endmill (or something like that). I think he goes through the process of making the necessary decisions based on the recommended info from an insert supplier. Whilst it is milling related, the process is very similar to turning.

If you go to the Walter site you should download the calculator mentioned in PixMan's post.

[PixMan]

Yes Pete, the smaller numbers on the chart are for feed rate per revolution in inches per rev.

As for the P15-P30 and other data, that's material types in ISO classification.

P = carbon steels, ferrictic and martensitic stainless steels
M = austenitic (non magnetic) stainless steels
K = cast iron, short-chipping
N = non-ferrous, copper, brass, bronze, and aluminium
S = superalloys, iron or cobalt based, titanium
H = hardened steels over 55Rc/400HBn
O = plastics, other long chipping soft materials which may also include glass and fiber filled

The 05-50 numbering system relates to the toughness of the carbide within its class. A "P10" would be harder, more wear resistant, while a "P40" would have a higher cobalt binder content and be tougher, more resistant to breakage under interrupted cuts.