Thread: Mazak still take a big cut?

How 'big' of a cut can a QTN250 take?

-Material, Feed, Speed, DOC or qubic inch/minute are what I'm really hoping for.

We're considering a new QTN250, and one of the things that come up from all people we talk to is that the newer Mazak's can not take as large of a cut as they used to... But no one can give me any real numbers. If the machine can only make 0.2"DOC@0.014"/rev in mild steel now, I really don't see that disadvantage outweighing the controllers advantage for a jobber shop like ours. So please, some actual experience with numbers to support would be very helpful. I'm concerned this is similar to people's hate of linear ways on milling machines, which allows for new milling techniques (requiring higher feed rates). In these situations a less expensive machine can produce as much or more in a day.

Pat

i have some numbers for you

these are from a qtn 100m a smaller one with square shanks of 20mm

steel 1045 diam +- 150mm ap 3mm vc=300m/min feed. between 0.25 /0.3mm/rev
machine will be at around 100% but it will take it really good

for ss 304 diam 150 ap3mm vc=130mm feed between 0.25/0.3 mm/rev.

i am really happy with mine and there wasn't a time i would hope it could go faster with the machine.
assuming you have a 25mm square toolholders i think you would be able to get an ap of 4mm with a feed of 0.4/0.5mm/rev without much problems

insert drill of 30mm around 180/m vc and a feed between 0.05 /0.1mm/rev in all materials i have done on it . the reason for the reduced feed is not the spindle motor but the trhurst on the Z axis running at around 100% with that date

There it is aggin - a Z thrust issue on yet another machine.

But boy - those long pitch screws sure rapid fast don't they!




---------------------

Think Snow Eh!
Ox

The Mazak QTN's have some of the highest spindle horsepower ratings of any new cnc lathes, for their respective size. Granted, the peak hp numbers are not the real, continuous hp, but nonetheless, Mazak has always had powerful lathe spindles.

The QTN250 is a 35 hp peak machine, I think. Maybe 25 hp continuous? That's stout for a 10" chuck machine! All the QTN's are integral-motor-spindle machines, which make for a quiet and smoooooth spindle.

For OD cutting, spindle hp is more important than Z-axis thrust, imo. On my older Mazak's with powerful belt-drive spindles, the load meter on the spindle always runs higher than the Z-axis when taking heavy cuts. That being said, I have never ran out of available horsepower on my Mazak lathes.

Now, for drilling, Z-axis thrust tends to be more important. Ox is correct, all newer cnc's have higher pitched ballscrews to enable those fast rapids, but you do lose effective thrust. Now, my older Mazak QT's have nice, slow-pitched screws that will push the turret through a brick wall...if needed!

To get more effective hp and torque in a 8"-12" chuck sized machine, you would have to find one with a gearbox drive for the spindle. I don't know of any new machines in this size range that are gear driven these days....

Originally Posted by cnctoolcat

The QTN250 is a 35 hp peak machine, I think.

BLASPHEMY! Peak rating is Haaspower term, which relates to: "Wind it up full speed, clamp a brake on it until it stalls, and record the highest amperage value recorded before the explosion." Not unlike my "8 peak HP" Shop Vac that plugs into a 110 wall socket.

The QTN250 is 35hp for 30 minutes, 30hp continuous. I've got a buddy that runs his QTN250s non stop on big nasty 15-5 forgings, just RIPPING material off.

Thanks for the replies everyone, your all giving me good information to help make this decision.

First I don't think I explained myself well enough, in simple terms I want to know how rigid the machines are. But since there is no way to measure it directly I'm hoping to get an indirect measurement through cutting data.

I'm also going to play devil's advocate, because I find it gets people to question assumptions they didn't even know they were making. This doesn't mean I don't want to Mazak, honestly I love Mazaks. I simply need to decide based on fact, not my personal bias.

I'm going to convert those metric #s to imperial, not because I don't like metric (I actually prefer it) but because I'm not used to using it for cutting data, and I imagine others are the same.

1045 material: 0.1181" DOC, 984SFPM, upto 0.012"/rev @ 5.9" starting diameter =
17 cubic inch/min
304SS: same with 426SFPM = 7.4 cubic inch/min
Drill: 1.181" Diam, 590SFPM, 0.004"/rev = 8.4 cubic inch/min

These are the kind of values I've been lead to believe would be the MAX the QTN250 could do. Although these are not amazing removal rates by any means, they are not notably poor.


Ox: The Z-thrust issue seems to be a common one in all the machines in this price range, I think i'll be stuck boring more often. Although 0.004"/rev really worries me, thats far too low for anything but an insert drill to run in that size. And even the insert drill is going to be rubbing inserts to death. I think I should look closer at the servo power, and ball screw lead on the other brands.

CNCtoolcat:
As for gear box machines, I happen to be considering one: Hyundai-Kia SKT250

Please don't take this the wrong way, but you sound like most of the sales men. From every machine I've used in this quality or better, you don't run out of HP. So.... Since you don't run out who cares how much there is? If that same machine had a 50hp motor on it would it be any better than the now 25hp?

HP in a machine is like HP in a car, "If you can't put it to the road it doesn't matter". In machine terms if it can't take a 'big' cut because of chatter, machine flexing, tooling limitations, working holding limitations, or material limitations than the extra power is just wasted $$.



Joe788:
Again I mean no offense, but "RIPPING" is a qualitative term that is different for everyone. I used to think 0.1" DOC at any speed or feed was a big cut. I also used to think you could only remove metal quickly with high DOC techniques, but now I use a 1" feed mill on my VMC with great success.

It is nice to hear it does well in forging though, as I feel the outside layer and uneven cut require more rigidity of the machine than turning bar stock.


Pat

Originally Posted by patindahat

I'm going to convert those metric #s to imperial, not because I don't like metric (I actually prefer it) but because I'm not used to using it for cutting data, and I imagine others are the same.

1045 material: 0.1181" DOC, 984SFPM, upto 0.012"/rev @ 5.9" starting diameter =
17 cubic inch/min
304SS: same with 426SFPM = 7.4 cubic inch/min
Drill: 1.181" Diam, 590SFPM, 0.004"/rev = 8.4 cubic inch/min

These are the kind of values I've been lead to believe would be the MAX the QTN250 could do. Although these are not amazing removal rates by any means, they are not notably poor.

Pat, those numbers were for a QTN100. It's drastically smaller than a QTN250. It's only a 15hp, 6 inch chuck machine. Expect much more from a QTN250.

Joe788:
Again I mean no offense, but "RIPPING" is a qualitative term that is different for everyone. I used to think 0.1" DOC at any speed or feed was a big cut. I also used to think you could only remove metal quickly with high DOC techniques, but now I use a 1" feed mill on my VMC with great success.

It is nice to hear it does well in forging though, as I feel the outside layer and uneven cut require more rigidity of the machine than turning bar stock.


Pat

No problem, I know what you mean. I'll see if I can get him on the horn today to get some real numbers for you. And yes, these forgings are 8 inch diameter, with a huge parting line on the face that takes a serious beating to remove.

I was thinking the same thing between QTN100 and 250, but honestly haven't even looked at the 100 so who knows. If you could get me numbers that'd be fantastic!

I'm tired of people going "Linear ways=HAAS". I have a hard time believing Mazak would give up THAT much rigidity for speed and price.

Pat

Originally Posted by patindahat

I was thinking the same thing between QTN100 and 250, but honestly haven't even looked at the 100 so who knows. If you could get me numbers that'd be fantastic!

The 250 is a significantly larger machine than the 100. If you see them in real life, the 100 looks like a toy.

I'm tired of people going "Linear ways=HAAS". I have a hard time believing Mazak would give up THAT much rigidity for speed and price.

Pat

There's a reason Mori, Makino, Mazak, etc all make their biggest, beefiest, nastiest titanium-cutting HMCs with linear guides. They are extremely rigid.

Here's what we do with our 2004 Nexus 200's (Older model of the 250 - same spindle rating as the 250)....24 hours a day, average of 6 days a week....

3500 RPM, Ø3-5" (mostly 4") face plunge (think Ø4" flat faced or custom profile insert drill), 0.6 mm / rev (0.023" / rev) in a nasty 18% Si aluminum alloy. The 5x - 1/2" IC Inserts are PCD tippped. LOC is between 0.240" and 0.6". It then does a profile pass on the OD & face with a separate tool.

It does this every 9.0 seconds and has since the first quarter of 2004.

It's actually cutting while the spindle is still ramping up to speed. It is well over 12 million cycles now. We had to replace the spindle in February for the first time (Bearings got noisy), it' still on the original screws and rails and still holds 20 microns all day long.

We've got several old Squirt 10/15's ('94-'98) with over 30 million cycles doing similar things. Course, couple of screw changes in there, 3 or 4 spindles and 1 new set of rails/trucks.

They've solved a lot of the Z thrust issues with the Nexus series. The SQT200's that were the predecessor to the Nexus line are weak in Z thrust, got a 20 hp spindle with those, but couldn't use it because you didn't have thrust in Z. We've got a few of those too. During the above cut, they will bog the spindle down about 1100 rpm during the cut, and you have to change the tools more often because of the reduced Z thrust. These machines were the 1999-2002 models. The nexus redesign was a leapfrog improvement to this series of lathes.

We've never had a Z thrust issue with the nexus series.

Do my eMachines count??? I'm told they're EXACTLY like a QTN250....
.
.
except they're turned up on it's end as a VTL...
.
.
except they have a 50HP turning spindle...
.
.
except they have more Z thrust...
.
.
except they have 5900 pounds of torque...
.
.
and a 75HP mill spindle to boot....
.
.
But they make great QTN250 parts!?!? ....
.


...... oh hell..... Never mind! (too much time on a Saturday making parts.... as delirium sets in... )

Another advantage of the Mazak Nexxus lathes is the value. They can be purchased for a lot less money than an equivalent-sized Mori, Okuma, or Nakamura...which I consider to all be in the same high-quality class.

The high-quality Korean machines like Doosan (Daewoo) and Hyundai/Kia aren't going to be much cheaper than a strongly negotiated deal on a Mazak Nexxus. Even if the Mazak costs more, 5 or 10 years down the road the Mazak is going to have a much higher resale than the Doosan or Hyundai. When weighing the true cost of a cnc machine, resale value should be considered...even if you don't ever plan on selling it.

As far as your rigidity concerns, the Nexxus lathes use a new generation of linear guides that create a machine with rigidity approaching a box-way machine. The Mori, Okuma, and Nakamuras are still box way machines. Yet, the Mori uses linear guides for the tailstock...go figure.

Horsepower, and torque, are important factors in cnc lathe performance. Years ago about all cnc lathes had gearbox drives to get the low end torque to cut large diameter parts. Now, with advances in motor and drive technologies, the direct drive spindles can emulate the low end power of a gearbox machine.

It's hard to say what your limitations would be when making an aggressive cut. I agree it's probably not going to be horsepower, or Z-axis thrust, or even machine rigidity, on any of the top Japanese lathes. I would think workholding, or tooling would be your limiting factors. You will have this on any machine you buy.

With advances in carbide tooling, lathe machining has become more of a "high speed" affair, much like milling has. Carbide inserts are now capable of 1000 SFM or more in steels, about double that of a decade or so ago. And I have found, maximizing SFM is the easiest way to get productivity out of a cnc lathe. DOC and IPR are important, but using the new carbides at hyper SFM's is how I make money.

Good luck, and keep us posted.

You consider KIA a "High Quality Korean" machine?

Is that b/c those are the only Korean machines you can think of - or you really think they are good?


I have a chumm that had a KIA for a while. He was NOT happy with it - and the biggest dissappointment BY FAR was the service that he got through the dealer and KIA. I forget what all the issues were, but it was basically a red-headed stepchild that IFAIK there were only two in the States, but still....

I don't recall that machine having all that much iron in it either?

Oh well, I am sure that he didn't give nut'n for it anyway. (it was new)

I don't have a clue of the model.


----------------

Think Snow Eh!
Ox

Originally Posted by psychomill

Do my eMachines count??? I'm told they're EXACTLY like a QTN250....
.
.
except they're turned up on it's end as a VTL...
.
.
except they have a 50HP turning spindle...
.
.
except they have more Z thrust...
.
.
except they have 5900 pounds of torque...
.
.
and a 75HP mill spindle to boot....
.
.
But they make great QTN250 parts!?!? ....
.


...... oh hell..... Never mind! (too much time on a Saturday making parts.... as delirium sets in... )

I don't see the point of that much power and torque...it's not even usable since that is a linear guide machine.

Ox,

Hyundai/Kia are generally considered a high quality Korean machine.

A local shop runs a bunch of them, and swears by 'em.

H/K are making the fancy, articulating, tool-changing head, sub-spindle, multi-tasking machines. A builder couldn't build a machine like this without some knowhow. (Haas don't....)

Now, I have heard of lemons with any brand. Sometimes a bit of the "lemon" can be attributed to the user...

From what I've seen I'd agree with CNCtoolcat. There are both alot of Mazak, and alot of Hyundai-Kia around here. If the H/K had a better controller I wouldn't have even got a quote from Mazak, though I'm happy I did as the price is much closer than I expected. List price the H/K is only $5000 less.

I think my next step is to get a demo of a local QTN250, even if its a nexus 1. This will allow me to see first hand how it handles itself, and help the other person involved in the decision why I'm sticking up for the Mazak.

Pat

Originally Posted by cnctoolcat

Ox,

Hyundai/Kia are generally considered a high quality Korean machine.

A local shop runs a bunch of them, and swears by 'em.

H/K are making the fancy, articulating, tool-changing head, sub-spindle, multi-tasking machines. A builder couldn't build a machine like this without some knowhow. (Haas don't....)

Now, I have heard of lemons with any brand. Sometimes a bit of the "lemon" can be attributed to the user...

My chumms was a sub spindle lathe. (Live tool I ass_u_me as well.)

One example that I remember is that he had asked for a new sub spindle collet closer. A yr later and nothing showed up. There were some ladder issues too as I recall, but I don't know what enymore.

Finally got trade in credit - and believe it or not was able to buy a nother brand - but through the same distributor. It is aggin - yet another (non-Jap) import - and he has had issues with that one as well. But he seems to have it under control now.

Their just not his old Cinci - that's for sure.


----------------

Think Snow Eh!
Ox

I've also had some support issues with Hyundai
if the only way you can make a buck is to bury the needle every day all day
you better have solid access to parts and service

et a demo of a local QTN250, even if its a nexus 1

Hey Pat, all QTN's are the Nexxus machines. They go up to a QTN 450, and are all made in Florence, KY.

The Nexxus series came out about 2000, and was a complete redesign from the fantastic QT's, which had been built since about '82.

They build quite a few lathes in Florance Y'all?

I thought they did mostly just the mills?

The more they doo there - the higher they will be on my option list!

The Yanks leave so much of the turning capacity unsupported. (Don't offer machines with X capabilities.)


------------

Think Snow Eh!
Ox