What insert profile

[DaveH]

Correct
 
DaveH

[DaveH]

(04-09-2015, 12:04 PM)aRM Wrote: Only thing is I know we have mostly WNMG  and  CNMG  type toolholders which we need to check on and see if we can get similar to what U suggest.
aRM

Well that's a bit of a blow   I'm not a big fan of negative inserts although  they do have some advantages double sided, good for taking heavy cuts less prone to break.
However if you want to get a good finish I think positive inserts are the best. They also require less power for the cutting and less force on the workpiece.

So I think you may have to purchase a holder that is suitable for positive insert.

Just my 2 cents

Just as a thought do you have any boring bars?

DaveH
 

[aRM]

(04-09-2015, 10:33 AM)PixMan Wrote: The tool nose radius as it relates to feed rate has a profound effect upon the surface finish you get. Also, it's often critical to use at least the size of the tool nose radius as your minimum depth of cut. That's primarily true with carbide inserts because they need heat in the process to get a shiny finish in most materials, soft steels in particular.

Those inserts which have a molded-in chipbreaker (top form geometry) will have a range for depth of cut and feed rate and feed rate in the materials which a particular grade and coating were aimed at. In general terms a larger tool nose radius will get a smoother finish than a smaller radius if both are run at the same feed rate per rev. The profile shape of an insert (90º, 80º, 55º, 35º) and the approach angle of its holder have an effect too, just much less pronounced.

If you are using CNMG and WNMG negative rake inserts, tell me what materials you are turning, and the amount of stock removal you wish to get per pass. Also, the spindle power of the machine will matter with negative rake inserts. I would hope you have at least 3HP on the lathe to use negative rake inserts effectively. I can help with chipbreaker selection and grades when I learn more about what you are trying to use and what materials you are cutting.

Your machine certainly appears to be right for these inserts, I simply don't understand the bit about "keep in low"! If that's what they want, why is the lever option there at all? Perhaps they want it in low only for threading? You definitely want higher speeds and feed rates. I can't quite see the top information plate in your photo, but it appears you have a specific gear arrangement for turning feed rates. See if you can find in your machine's documentation why the notation about "Keep In Low."

Ken

Hello KEN
Always good to hear from U.

We have usually tried to maintain an 0.10mm depth of cut when taking a finish pass.  And also experimented to see if there was any difference in applying Cutting Oil direct to the part, which seemed not to make any difference. Now that U mention that Carbide Inserts need the heat to generate that polished finish, it all comes together.

The materials we generally turn are the usual lot of salvaged "unbeknown" scraps and  some special boughts comprising Mild steels, BMS, Tool steels  including and not exclusive to Silver Steel,  303 SS, 316 SS, a little on our 4 Grade Knife Steels,and the usual lot of NFM's  viz Brass, Bronze  and  quite a bit of Aluminium. We are really not hurried to take heavy cuts and at the most have taken 3.0 - 3.5mm heaviest cuts, and this too, not often times. Looking at the machine specs, it says Spindle Drive Motor 4P/8P, 3PH 3.3/2.2 kw or 4.5/3kw 4P, 3PH 90W !!!  I will only be able to check out the Motor on Saturday to really get the exact specs and revert with the correct info. Do bear with me. In the interim I am pretty sure it is a 3HP Motor, if not more.

Have attached 2 more pics of the machine to give U a better idea.  Will also research that bit on the "Keep in Low" reason in the Manual, which I highly doubt has any further elucidation,  and I think my best bet would be to contact and find out from the Sellers personally. Will let U know, either way.  

Thanks a stack
aRM

[PixMan]

For the inserts, consider the newest Walter grade WMP20S in the NF4 (finishing) and NM4 (medium-roughing) chipbreakers. The grade is the best "all around" grade I've ever seen and is good for steels, stainless steels and some exotics. Not as sharp as an uncoated polished one in aluminum, but it will work if you use heavier depth of cut and higher feed rates.

I'm very curious about that "Keep In Low" thing, it sure doesn't make any sense.

And yes, a 3.3/2.2 Kw motor is 3HP. The 2.2 / .74 equals just about 3HP, the 3.3 / .74 is the 4.5HP 20 minute duty cycle for overtorquing it.

[aRM]

(04-09-2015, 01:03 PM)DaveH Wrote:

(04-09-2015, 12:04 PM)aRM Wrote: Only thing is I know we have mostly WNMG  and  CNMG  type toolholders which we need to check on and see if we can get similar to what U suggest.
aRM

Well that's a bit of a blow   I'm not a big fan of negative inserts although  they do have some advantages double sided, good for taking heavy cuts less prone to break.
However if you want to get a good finish I think positive inserts are the best. They also require less power for the cutting and less force on the workpiece.

So I think you may have to purchase a holder that is suitable for positive insert.

Just my 2 cents

Just as a thought do you have any boring bars?

DaveH
 

Heck DAVE, never knew that there was Toolholder specific for a "Positive Insert" !!! Would that be in the DCLNR, DWLNR type Toolholders ???
Do U have any specific holder in mind ??? Let me know as I am presently negotiating getting some down as well.

Bought a cheap set of Boring Bars from "Flea Bay" - like they say, and these came with their own Carbide Inserts as well. Nothing too exclusive, and we knew not better at that time. Also have a mini Mitsubishi with Inserts which is not practical for my 20.20 QCTP Holder. Finally, and a large brazed Carbide one, also to fit the 20.20 holder, but which we only recently realised, requires the QCTP to be shimmed some +6mm to get it on exact Centre to the spindle Bore.

And the reason for asking Dave ??
aRM

[aRM]

(04-09-2015, 02:40 PM)PixMan Wrote: For the inserts, consider the newest Walter grade WMP20S in the NF4 (finishing) and NM4 (medium-roughing) chipbreakers. The grade is the best "all around" grade I've ever seen and is good for steels, stainless steels and some exotics. Not as sharp as an uncoated polished one in aluminum, but it will work if you use heavier depth of cut and higher feed rates.

I'm very curious about that "Keep In Low" thing, it sure doesn't make any sense.

And yes, a 3.3/2.2 Kw motor is 3HP. The 2.2 / .74 equals just about 3HP, the 3.3 / .74 is the 4.5HP 20 minute duty cycle for overtorquing it.

Yes, Yes, Yes Sir, we knew U'd have an good answer to our quandary
Will talk to Walter in the morning.
And finally, what holder would these Inserts fit in, hope in some of my existing ones !!!

Will definitely let U Guys know about that Lever first thing on the morrow, LORD WILLING. I am mighty curious as we would love to use this machine to its full potential
aRM

[DaveH]

(04-09-2015, 02:52 PM)aRM Wrote: And the reason for asking Dave ??
aRM

If you have some insert boring bars then it is possible to use some of the positive inserts for both. That is to say the same inserts can be used for the external tool holder as well.
It minimizes the  number of different types of inserts one has to purchase and stock.

DaveH

[DaveH]

(04-09-2015, 03:04 PM)aRM Wrote: And finally,  what holder would these Inserts fit in, hope in some of my existing ones !!!

aRM

aRM,
The holders you have
What Ken has given you is the grade - what the insert is made from,  basically the specification of the material for the insert and it's performance.
So you will ask for the insert size that fits your holder and you tell them what grade you want in this case WMP20S - NF4

What you really need to do is shop around prices can vary a considerable amount. Some may have specials whereby you buy a holder and they will give you 10 inserts for free they know you will buy more inserts. But beware make sure the holder is an ISO standard, that way you can purchase inserts from any supplier.

DaveH

[PixMan]

That WMP20S grade is available in CNMG, DNMG, SNMG, TNMG, WNMG, and VNMG in negative rake inserts. In the screw-down positive rake, it's available in CCMT, DCMT, SCMT, TCMT, and VBMT shapes. There are several chipbreaker choices in each.

And what DaveH says about the holders is true. If you are buying any make sure they are an ISO standard rather than proprietary. You can run anything you find by me if in doubt. I may know something about the technology and terminology. ;)

BTW, if I ever run low on any insert style (not likely) I'll be stocking up on everything in that grade because then I'd have ONE grade for everything except cast iron. And for the little bit of that I rarely see, I'll either use up the remaining flat-top CNMA/DNMA inserts I have or just limp along with the WMP20S.

[aRM]

(04-09-2015, 03:56 PM)DaveH Wrote:

(04-09-2015, 03:04 PM)aRM Wrote: And finally,  what holder would these Inserts fit in, hope in some of my existing ones !!!

aRM

aRM,
The holders you have
What Ken has given you is the grade - what the insert is made from,  basically the specification of the material for the insert and it's performance.
So you will ask for the insert size that fits your holder and you tell them what grade you want in this case WMP20S - NF4

What you really need to do is shop around prices can vary a considerable amount. Some may have specials whereby you buy a holder and they will give you 10 inserts for free they know you will buy more inserts. But beware make sure the holder is an ISO standard, that way you can purchase inserts from any supplier.

DaveH

Hello DAVE
Thank for the clarification - that does make things much clearer

Guess we just a bit lucky in that we can get our Tooling at wholesale prices, so there's only one Walter supplier we need to talk to.
Only thing is we have to talk to a Lady who knows just as much as us about these things !!
She did send me the CNMG List but like KEN had said, these are the very latest and they are definitely not listed, as we double-checked on our Walter catalogue as well
.
So, we going to chase her first thing on Monday and make sure we have the right ones, LORD Willing.
Take care and like we say, 'be vigilant' !!
aRM