What inserts do you like and why?

[Former Member]

www.shars.com download their catalog goto page 107 to 140 they have a good selection and read. Better than KBC unfortunately.

 

[PeterT]

When I use round inserts for finishing purposes, my depth of cut might be 10 to 5 thou or even less. So the cut does not involve the entire radius - only a very small arc of it.
For the best finishes, I don't use the round inserts either, I use a hss shear tool. And of course, it all depends on what you are after.

Maybe some of the folks who do his for a living can comment if I'm interpreting the insert manufacturer recommended operating envelope properly (the little chart that typically accompanies the insert description), or if I'm out to lunch. I do accept that this is 'recommended' & likely focused on their customer base (predominantly CNC machines). But OTOH the world doesn't explode if you operate slightly outside the range on a hobby lathe. But just in general terms, does this logic go around?

if I take @thestelster Sandvik catalog showing the 2 round inserts, a couple observations
- they appear to be for quite different purposes despite both being 'round'. I marked up the operating range from RNMG & superimposed onto RCMX. RCMX appears to be a substantially more aggressive operating envelope, both in terms of DOC & feed
- the RNMG envelope base (the minimum DOC) is 0.047" That is a healthy cut
- for visual reference I drew a 0.002" DOC (dash pink line) just to provide a common reference. No logic to selecting that particular value other than many of us can relate to that as being somewhat like a 'finishing cut' in our hobby domain, creeping up to a target dimension finish on something important. Notice how pink line is substantially below the envelope of both RNMG & RCMX range, but its way below RCMX

I grabbed Dorian catalog randomly, link below. They have lots of finishing inserts listed, majority of which are faceted (non-round).
- Screen grab shows their operating range, a bit different format but I think consistent units? I made a boundary box (blue) around the finisher

Excel plot shows the 3 inserts superimposed to each other. I didn't capture the RCMX curve envelope quite correctly, but you get the general idea.
- look at the 0.002" DOC pink line relative to the faceted insert. It seems it is designed for this type of skimming

@Susquatch using your example 0.005-0.010" DOC range, still a distance below the minimum recommended RNMG. But lets assume the finish is spectacular, that DOC value presents a more challenging operating strategy. Because if you want to hit finish AND dimension simultaneously, say a shaft to fit a bearing, you step in say 0.010" increments. If you are off 10%, that's 0.001". If you select the UEU finisher, the increment step cane be is 0.002", 10% deviation is 0.0002"

If I'm misunderstanding interpretation of the plots please let me know. Pretty sure we have chatted this topic in the past, because my next line is.... what would be REALLY useful is to see HSS on the same format plot. Ever seen references along those lines?

https://www.doriantool.com/wp-content/uploads/dorian_tool_TurningTools_CarbideInserts_.pdf

 

[Former Member]

I'm going to mess things up a little and back track to interrupted cutting with....

Let the fur fly.

 

[PeterT]

FSWizard app

@thestelster do you need to create an account to run? When you say app do you mean phone or PC or does it make a difference?
Looks like it has some useful calculation metrics, but it doesn't seem to be responding to new inputs. I was hoping to evaluate HP as a function of nose radius for HSS.

 

[Susquatch]

Susquatch using your example 0.005-0.010" DOC range, still a distance below the minimum recommended RNMG. But lets assume the finish is spectacular, that DOC value presents a more challenging operating strategy. Because if you want to hit finish AND dimension simultaneously, say a shaft to fit a bearing, you step in say 0.010" increments. If you are off 10%, that's 0.001". If you select the UEU finisher, the increment step cane be is 0.002", 10% deviation is 0.0002"

If I'm misunderstanding interpretation of the plots please let me know. Pretty sure we have chatted this topic in the past, because my next line is.... what would be REALLY useful is to see HSS on the same format plot. Ever seen references along those lines?

I can't really comment much on what you have posted Peter.

I do agree with your comments about creeping up on dimensions. I don't have the knowledge or skills or confidence to do that with a carbide insert of any type. I would only ever use HSS for that. Your 10% error window is a good way to look at it. I can't begin to try the approach I've read others write about where they take 10 or 20 off to hit a final number. Doesn't work for me - I creep up on it. Not always successful even at that. My use of the round inserts is strictly finish and stress relief.

046 minimum cut? Ya, that is F23 territory.

Thanks for posting the Dorian link. I added it to the insert reference thread.

Also not going to comment on the Dorian data or your interpretation of it. Maybe some day after I get some inserts and holders of that quality.

I don't think I've ever seen anything like that for HSS. I'll certainly keep my eyes open.

 

[Susquatch]

I'm going to mess things up a little and back track to interrupted cutting with....

Let the fur fly.

Not a very good example of interrupted cuts. They still start gradual and don't hit a sharp edge or corner. In other words, the shock load is very low.

 

[thestelster]

Maybe some of the folks who do his for a living can comment if I'm interpreting the insert manufacturer recommended operating envelope properly (the little chart that typically accompanies the insert description), or if I'm out to lunch. I do accept that this is 'recommended' & likely focused on their customer base (predominantly CNC machines). But OTOH the world doesn't explode if you operate slightly outside the range on a hobby lathe. But just in general terms, does this logic go around?

if I take @thestelster Sandvik catalog showing the 2 round inserts, a couple observations
- they appear to be for quite different purposes despite both being 'round'. I marked up the operating range from RNMG & superimposed onto RCMX. RCMX appears to be a substantially more aggressive operating envelope, both in terms of DOC & feed
- the RNMG envelope base (the minimum DOC) is 0.047" That is a healthy cut
- for visual reference I drew a 0.002" DOC (dash pink line) just to provide a common reference. No logic to selecting that particular value other than many of us can relate to that as being somewhat like a 'finishing cut' in our hobby domain, creeping up to a target dimension finish on something important. Notice how pink line is substantially below the envelope of both RNMG & RCMX range, but its way below RCMX

I grabbed Dorian catalog randomly, link below. They have lots of finishing inserts listed, majority of which are faceted (non-round).
- Screen grab shows their operating range, a bit different format but I think consistent units? I made a boundary box (blue) around the finisher

Excel plot shows the 3 inserts superimposed to each other. I didn't capture the RCMX curve envelope quite correctly, but you get the general idea.
- look at the 0.002" DOC pink line relative to the faceted insert. It seems it is designed for this type of skimming

@Susquatch using your example 0.005-0.010" DOC range, still a distance below the minimum recommended RNMG. But lets assume the finish is spectacular, that DOC value presents a more challenging operating strategy. Because if you want to hit finish AND dimension simultaneously, say a shaft to fit a bearing, you step in say 0.010" increments. If you are off 10%, that's 0.001". If you select the UEU finisher, the increment step cane be is 0.002", 10% deviation is 0.0002"

If I'm misunderstanding interpretation of the plots please let me know. Pretty sure we have chatted this topic in the past, because my next line is.... what would be REALLY useful is to see HSS on the same format plot. Ever seen references along those lines?

https://www.doriantool.com/wp-content/uploads/dorian_tool_TurningTools_CarbideInserts_.pdf

Hi Peter, with those round inserts by Sandvik, the RCMX info is based on an insert size of 20mm (0.787"), while the other one the data is for a 1/2" insert. That's why the max depth of cut is so different between the two. So you can't compare the two. Plus the RCMX has 2x the edge width (0.008") compared to the other. The wider the edge, the stronger, designed for roughing.

 

[thestelster]

@thestelster do you need to create an account to run? When you say app do you mean phone or PC or does it make a difference?
Looks like it has some useful calculation metrics, but it doesn't seem to be responding to new inputs. I was hoping to evaluate HP as a function of nose radius for HSS.

Hi Peter, yes you're right, it doesn't change the results for different nose radii. Perhaps on the pay version it works? But most everything else it does. Once you change an input, click somewhere else on the screen and it will change to the correct values.

I have the app on my Android phone.

 

[johnnielsen]

To answer Susquatch's original query, I have used predominantly dnmg 432 to 435
coated inserts, mostly Sandvik, since 1979. A right hand tool holder with 2 degrees of lead allow me to turn, face and plunge which is a real timesaver when you want to make chips.

 

[PeterT]

Thanks for posting the Dorian link. I added it to the insert reference thread.
Also not going to comment on the Dorian data or your interpretation of it. Maybe some day after I get some inserts and holders of that quality.

Just to clarify, Dorian is above my pay grade. I'm just a catalog grazer. I have a few euro toolholders purchased from KBC a while back. Decent quality (for me) & it was still less than the big boy brands. I also sampled a few inserts from the likes of KBC & Travers. Once I started buying from Ebay sellers (sometimes Ali too but I'm more picky) I was hard pressed to tell the difference to justify the cost, so that is what I've stuck with. Now is my Ebay Korloy a real Korloy? I don't know. But my experience thus far is I cant wear them out fast enough in my lifetime to fret about it when a box of 10 is $25 or whatever. Most chipped edges are self inflicted, but I also don't do much heavy cutting or hard material turning. The biggest performance/finish differences have been the type of insert itself. The Ebay suppliers take the $ sting out of trying others. Recently I tried some optimized for stainless & they did seem better than the general steel ones I used prior. The Ebay/Ali toolholders seem to be semi hardened 4140. Nothing special but they seem to do the job.

Another good technical reference is Korloy. I've had to cross reference certain PN's when I see them on Ebay type seller sites. Korloy publish a few different documents, some are higher level summary (digest) or you can geek out with the technical catalog.

Catalogue | Download | KORLOY

Catalogue | Download | KORLOY

www.korloy.com

 

[Susquatch]

Hi Peter, with those round inserts by Sandvik, the RCMX info is based on an insert size of 20mm (0.787"), while the other one the data is for a 1/2" insert.

Holy Crap! A 3/4" round insert! Ya, that's F35 territory! Even 1/2" is big for me. My big one is maybe 3/8 and my small one is maybe 1/4 (but I didn't measure them). Regardless, the bigger they get, I think the harder it becomes to get a good finish. I might as well be trying to use a huge parting tool. That's prolly also why my small tool is so well used compared to my big one. Again kinda the opposite of your bigger ought to be better scenario @PeterT. Or to put it a different way, maybe smaller is closer to a large radius tip on a rectangular insert.

 

[Susquatch]

Just to clarify, Dorian is above my pay grade. I'm just a catalog grazer. I have a few euro toolholders purchased from KBC a while back. Decent quality (for me) & it was still less than the big boy brands. I also sampled a few inserts from the likes of KBC & Travers. Once I started buying from Ebay sellers (sometimes Ali too but I'm more picky) I was hard pressed to tell the difference to justify the cost, so that is what I've stuck with. Now is my Ebay Korloy a real Korloy? I don't know. But my experience thus far is I cant wear them out fast enough in my lifetime to fret about it when a box of 10 is $25 or whatever. Most chipped edges are self inflicted, but I also don't do much heavy cutting or hard material turning. The biggest performance/finish differences have been the type of insert itself. The Ebay suppliers take the $ sting out of trying others. Recently I tried some optimized for stainless & they did seem better than the general steel ones I used prior. The Ebay/Ali toolholders seem to be semi hardened 4140. Nothing special but they seem to do the job.

This is good stuff Peter. I was under the impression that you were a fan of the big dollar tools since that's mostly what you quote. But you are still a significant step beyond me.

With a few exceptions, all my stuff is discount tooling and my inserts are either Ali or BusyBee or Accusize. I bought a few parting inserts from KBC and I love them. They actually work! That's a huge step forward for me.

In fact, that's sorta what started me on this journey. If KBC inserts are so much better, then maybe I should try a few other types...... I wonder what the guys who do this all the time use.......

 

[little ol' e]

In fact, that's sorta what started me on this journey. If KBC inserts are so much better, then maybe I should try a few other types...... I wonder what the guys who do this all the time use.......

I am referencing Susquach's post here, but throwing this out to all interested on the board here.

I began machining in 1982, manual mills, lathes, grinders, radial drills in a Tool & Die shop. Been machining ever since full time and continue to do so.

IMO, their is no difference between CNC lathe machining vs manual Lathe machining. The only difference with a CNC lathe is higher speeds/feeds- contour machining, quick thread turning etc. Plus, given the added HP/TQ and mass weight of the machines as most here know.
The plus side of CNC, begins with finishing IMO.
Roughing is just roughing across the board. ( as long as you can keep heat expansion down you can hit stock to leave tolerances for semi finishing. It is also possible to skip the semi finishing and go rite into finishing with the indexable tooling on the market these days.
For example,
You can rough to .012 these days, then get into finishing. ( As long as you use the proper insert grade and coating for the material your machining, with optimum speeds and feeds to limit heat expansion and wear of the inserts)

Finishing at higher speeds and feeds in CNC gives you good control, accuracy and surface finishes.
This step can often be very difficult for many to achieve on a manual lathe when machining tougher materials unless using indexable with coating/s.
Not to say it cannot be achieved manually, you just need to throw better quality inserts at it if you want to finish it within a reasonable time frame without having to constantly grind HSS and "uncoated carbide blanks". ( We know what grinding uncoated carbide will do over time to us without a mask, now add coatings...)
If you have good grinding experience with HSS, uncoated carbide, and time, then you can always get by with cheaper insert options available for something you want to machine quickly. ( KORLOY for example)

Let me see if my old brain can explain what Carbide inserts are all about while trying to keep it simplified.

Think about it as if you only have 3 grades of carbide inserts, with several different coatings to choose from ( Just keeping it simple )

1) General purpose insert with a few layers of coating- They can withstand some heat, shock, a little chatter yet still hold an edge unless rigidity becomes an issue through too much chatter. These inserts are decent for softer materials but as you get up into 4140, H13, P20 ( 38-45rc ranges) these inserts will wear very quickly.

2) Mid-grade inserts have addition layers of coatings to withstand heat for the most part. Therefore keeping the wear down before getting to the carbide.
These inserts can handle 4140, PH4140 into A2 D2 keeping your speeds and feeds in check for the material hardness your machining.
They can handle some chatter, shock and interrupted cuts but... Be careful,,,

Once the coating comes off, your on borrowed time and the next pass you will be changing inserts. ( Perhaps Degen or others could help explain coatings more in depth if he gets time here, since I'm not really up to speed with them. )

3) Hard grade inserts have the ability to machine harder materials with higher speeds and feeds. However, they need a constant feed, speed and chip load to survive.
They cannot take much shock, chatter or anything interrupting the cut , but, the insert can withstand more heat. You need to have a good uniform stock for this insert to perform its best. They have multiple layers of coating to make this happen.

- Button inserts- They are wicked, for ruffing and finishing but they need material to bite into or your just grinding with them slowly removing the coating.
Anything under .025 DOC, I find they just wear too quickly in a chip breaker form ( Dished insert) The flat top inserts have multiple coating layers, these are for lighter cuts but still like at least .015 material to bite into or they just ware away like grinding.

Any insert with a radius of .03 and up generally used for roughing and semi finishing only. They need to bite as well.
The same 3 simple principles apply when choosing a insert. ( Increased radius for ruffing at lower RPMS with coating that will withstand what you are machining.

Finishing inserts have smaller rads since you are running at higher speeds and feeds, be it manual lathe machining or CNC.
It all about what your manual lathe can handle and how consistent you can keep your DOC's at and cross feeds with the RPM you choose.

As I mentioned in the past, write ups are difficult for me lol.
I got 2 credits in grade 9 highschool so that should explain things haha.
I was a trade school guy when I left highschool at age 16

Hopefully what I did type helps to it simple enough for all.

 

[thestelster]

Here is a link to the Sandvik Turning Handbook:

https://coromantstrgprod.blob.core....=t+nlI3N0olYsL5dm9B6aRAK1xQ4IJyMVUl6z/8pLio0=

 

[little ol' e]

Without focusing on a brand of insert here....
These are my go to inserts daily for turning. Both CNC and manually.
They are mid grade with several layers of coating.
Keep in mind, the coatings are what makes these inserts last, not the carbide under them.
Once the coating has worn, I turn them. If not, I would be generating too much heat and friction, at that point... tolerances are difficult to hold at that point as well.
You can see the wear on the triangular insert coating. I could run them further but I know that edge won't hold up much longer now that the coatings have worn off.
I then use them inserts on the manual lathe since they are no longer useful on the CNC lathe. Unless I'm standing at the CNC machine waiting for them to go, again I'm on borrowed time with then on the CNC lathe.

Triangular for roughing, diamond for finishing... that's it.
I'll add a threading insert as well.

 

[little ol' e]

Different coatings shown below- Optimal for CNC turning, but can get expensive...
That is why I suggested Tialn coatings for the manual side of things. Be it lathe or mill.
No point in wasting your money on the high end coated stuff unless you are a seasoned machinist IMHO.

I looked on Aliexpress this morning... seen inserts with Tialn coatings.
For manual machining, I would start their since you guys are familiar with purchasing from them. I would not pay more for them from KBC, Korloy anyway. That is just my opinion thou since I have not tried any of them out.

Hopefully Degen can comment more about these coatings since he has the knowledge with these types of coatings and substrates, including TIALN coatings that I suggested for manual turning.

 

[Susquatch]

To answer Susquatch's original query, I have used predominantly dnmg 432 to 435
coated inserts, mostly Sandvik, since 1979. A right hand tool holder with 2 degrees of lead allow me to turn, face and plunge which is a real timesaver when you want to make chips.

Perfect John! Exactly what I have been after! Especially the versatility of turn, face, and plunge. I've liked off shore Trigons for turning and facing, but they won't plunge - at least not on my machine. If I could find a good tool and inserts that would be versatile, last long enough to be cost effective, forgiving of my many mistakes, and leave a decent finish behind that isn't embarrassing, I'd be a very happy camper. In fact, I'd even settle for a bad finish that needs cleaning up with another tool.

I don't suppose you have a recommended tool part number for them? Or do you think that is important?

 

[Dabbler]

I'd like to add a comment, certainly out of order.

I've used the cheapest of the cheap, mid-range and premium inserts over that last 40 years. Yes even before ISO designations for inserts were commonly available sizes.

Here's my take for a hobby guy, and until tha last 14 years using a 1.5 HP lathe and 1 HP mill.

If you use the cheap ones carefully, they will get you by. They are better than HSS in tough stuff like shafting (4330 in my case), but they don't last long and won't survive interrupted cuts or tough situations.

During all this time I also was using Kinnemetal tooling (holder and inserts) for a single tool, a triangle tool in my 12X37 lathe. Because the price of the inserts I tried to minimize their use, and developed a goo balance between cheap inserts, HSS and the Kinnemetal ones.

I agree that the trigon insert is superior to the triangle, because it is stronger, but I' don't have a holder for them.

Here's a bit of a kicker: The K tool holders aren't much more costly than any of the mid-range tool holders. I am looking to start tooling for CNMG for my bigger lathe and The holders are quite reasonable in price.

I've only had one time where the triangle tool was not up to the task: an 8" diameter 4140 PH steel pipe section I was trying to chamfer. The lath was just too flimsy for the tool pressure required on my 12X37, and I fractured the insert. Repeatedly.

If you have a small lathe, know that the cutting depths needed to really take advantage of carbide can be very hard or impossible if you lathe isn't rigid enough. You can help fix this by using inserts ground for finish on aluminum - for steel, but know they have a shortened life, but will work well.

 

[DavidR8]

I did a bunch of research on insert tooling and one key learning was that the nose radius is the minimum depth of cut. This has a lot of implications for us small lathe owners. If the radius is too large then there's a good possibility that the machine won't be able to make that depth of cut.
All of this lead me to use HSS far more than insert tooling simply because I can keep it razor sharp and take depths of cut that my South Bend 10K can manage.

 

[Susquatch]

Without focusing on a brand of insert here....
These are my go to inserts daily for turning. Both CNC and manually.
They are mid grade with several layers of coating.

Hey Eric, can you post part numbers for what you recommend as well as for the associated holders?

I see you have several different types as well as several sizes of that type. With time I may come around to that but not just yet. I'd prefer to stick with one size and maybe several different point radii and maybe 3 types (Stainless, Steel, Aluminium) unless one type will do all which would be a bonus!