Late 80's CNC 2 Axis lathe - Daewoo Puma 12L vs Mori Seiki SL-6B

Hi Everyone,

I have exponentially more experience with CNC mills and do five axis milling with Deckel Maho machines at this point. We have plenty of larger turning we farm out that we would like to do in-house and have two lathes readily available in storage but only room for one of them. I haven't been able to run either and I would like to hear what members that have actually run these machines think of them to help finalize the choice for us.

The lathes are both slant bed FAPT enabled Fanuc 10T controlled box-way machines so physically they are very comparable.

One is a Daewoo Puma 12L (Long version - 1050mm Z travel, 3" through bore) and the other is a Mori Seiki SL-6B (6.25" Big through bore version with Howa Pneumatic chuck).

I know typically Mori Seiki has a great reputation for this generation of turning center but I figured it couldn't hurt to ask anyway, most of what we will be doing is ID and OD API thread work from solid round bar on parts that range from 3" to 12" or more.

The Daewoo is a lighter lathe at around 15,600 lb and it has a belt/gearbox/belt/spindle drive system opposed to the heavier (20,000lb) gear driven Mori.

The Daewoo has a A2-8 hydraulic actuated (via drawbar) 12" chuck that can spin up to 2500 rpm whereas the Mori is A2-11 and maxes out at just over 1000 rpm. Daewoo max 1000 ish ft/lbs torque, Mori 2292 ft lbs. I think the Mori has at least 1 more gear than the Puma does.

The Mori has not only less Z travel (850mm) but the big air chuck eats up the distance between centers even more. I've never used an air chuck either so not sure what drawbacks there may be or if it might be a smart idea to just throw on a manual A2-11 4 jaw to get the Z back and keep the big bore?

The Mori has a programmable belt drive tailstock whereas the Puma is a manual drag along tailstock.

Probably the biggest pain about the Mori is the chip conveyor that must be removed from the end and cannot roll out with the coolant tank. I've read people suggest coolant touching the casting can cause accuracy problems but then I've also heard the SL series of this vintage are some of the best lathes made? Just the access needed for the chip conveyor in terms of floor space is a negative for the Mori SL. The Puma tank pulls out from the front and the conveyor can be removed by being lifted out by above or pulled out from the side. Most newer slant bed lathes look like they are built on the same architecture as the Puma, the Mori of that vintage is unique to them, but they ran with that casting design and changed the sheet metal for many years afterward.

Will having a max of 1000 rpm be a serious issue for finish on those smaller diameters? Threading is typically performed pretty slow anyway isn't it? Some pretty large drilling may come up 1.5" or more... but I imagine both lathes could handle it no problem.

A buddy near me has a big flat bed Haas with a 10" bore that has turned away some of the smaller threading work I would be doing because he said his max RPM made it not sensible to do the work. With 1000 rpm available what is the smallest dia I can go realistically in steel? 4140, 4330... I have a feeling someone is going to mention the SFM recommendation of the inserts being used, I'm not sure what happens if the part is run slower than these values? I have a Tree UP 1000 lathe with a 4000 rpm spindle and I think 1 ft lb of torque, maybe less. Heh.

Any thoughts, anecdotes or opinions are welcome on this. At this point we don't have nearly enough turning to justify a new purchase and would like make the most of what we have available.

Dave @ Nerv

In terms of build quality the Mori is light years better than the Daewoo.

I run carbide threading tools on my manual lathe all the time at 100 to 200 RPM ... when I was doing 6" .250 wall alum tubes I was threading at 60 RPM on the cnc ... any faster and it would drive ya nuts with the noise.

your not taking a heavy cut threading so with a sharp insert it works great... I have boxes of old school C2 non coated.

Over the years, even going back to where these machines were new, I have trained many shops on both machines.
I have always liked the Mori better, it was then the highest quality lathe available.
The 10T control as the Fapt(Fanuc Apt) was exciting, I pretty much had to figure out how to use it by myself, exciting but fun once I had it working.
Write back if you have any questions:
Heinz at doccnc.com

Thanks for the feedback thus far,

Does anyone have any manuals for a Mori SL-6 or 6B which show the installation diagrams? It would be nice to have some accurate overall dimensions and I can't find any copies of this documentation online anywhere.

The parts diagrams may be a good substitute. The Puma diagrams show the machine dimensions in the parts diagrams.

Either will work.
on 2" steel 1000 rpm is more than you need.

Both are excellent machines. The Mori is obviously a larger machine hence the reduced RPM and increased weight. The Daewoo would be the next size smaller. Much of this depends on "what" you're gonna cut. I like having a few more RPMS so modern tools can run a little better.
I work for Doosan (Daewoo) so I'm a little biased.

DouglasJRizzo said:

......I work for Doosan (Daewoo) so I'm a little biased.

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Good thing you put that little qualifier in or else we'd of needed to laugh you outta here.

I worked as a service and applications engineer for a Daewoo dealer in the late 80s to early 90s. They were nowhere near the same league of machine as a similar year Mori.

I hear, and agree with the comments about the Mori being by far the nicer machine.

But, the spindle factor should not be overlooked.

hanermo said:

Either will work.
on 2" steel 1000 rpm is more than you need.

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No.

For alloy steels in the mid '30Hrc, 1000rpm is workable for 3", but if you're turning down much below that you're going to hit a speed wall. If you're working with mild steels then it's straight up too slow.

The Mori will have horrible spindle acceleration compared to the daewoo too.

At 3", the daewoo will run circles around the Mori. At 12" it will be very much the other way about.

I would make room for both machines on the shop floor and get them operating. It's a shame for either one to be sitting in storage rusting away. Take a good look at your floor space and make them fit, then you would have plenty of options and turning capacity.

Make Chips Boys !

Ron

Thank you everyone so much for your feedback so far.

At this point I am most restricted in floor space than anything else. I can thank the 40k lb Deckel Maho MC800H for that, it's like a small building in my shop.

A summary of what I've read here is: Mori is better built, larger class and better suited to larger parts with anything below 3 inch getting pretty inefficient though perhaps still possible. Consideration of the exact range of parts that are expected right away should likely dictate the choice more than anything else.

As I noted briefly earlier, I do have a small box-way Tree "Up 1000" lathe that can spin up to 4000 rpm, it can handle just under 2" through the spindle and takes 3J collets or 5C with an adapter. I also have a taper adapter to accept a 10 inch set-tru bison scroll 3 jaw chuck. I hope the Mori can pick up from where the Tree can no longer be effective. The Tree has 18" of travel and a hydraulic drag along tailstock. 8 tool turret. An advantage of the Tree lathe is although it lacks a conveyor it takes up a very small amount of floor space. I took the cabinet off the back and changed how it is wired so now it is only 4' deep and can be placed directly against a wall on two sides. This fits under pallet racking which increases the volumetric efficiency of the shop even further.

On early 80's CNC machines, especially the older ones, the control cabinet was sometimes not attached to the machine and could be placed where it was most accessible. This was phasing out when the Mori and Daewoo were made, but the Daewoo in particular is really easy to pull the cabinets and hydraulics to remote mount so the machine can be placed against a wall and have only roughly 4' depth. The Mori in theory could do the same but they really optimized the positioning and wiring so it would likely take quite a bit more effort. Still, when you take into account the space you need to access cabinets by having room for the doors to open behind the machine it is easy for the machine to take over double the floor space because of the accessibility requirements. In this regard Hitachi Seiki was really elegant with some of the mills which have the main magnetics and control cabinet on the front of the machine which opens into the area the operator needs to stand to run the machine anyway. The VS machines can be placed against a wall on on side with only a few inches clearance on the back from from factory.

What limits how much this can be effective on the Mori is the belt housing/casting which attaches the X axis servo as well as the hydraulic counterweight cylinder. Those stick out and are likely the first objects to make contact with the wall if the cabinets are removed.

Anyway, thanks again for all the feedback!

Vancbiker said:

Good thing you put that little qualifier in or else we'd of needed to laugh you outta here.

I worked as a service and applications engineer for a Daewoo dealer in the late 80s to early 90s. They were nowhere near the same league of machine as a similar year Mori.

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I'll never knock the other guys, but we still build heavy, box way, geared head machines. Still use all Fanuc controls/motors/drives/electrics and we provide training free - for LIFE, whether the machine is new or used. We also still pour our own castings, heat treat and grind our ways in house.

I've been trying to get as much support documentation on both machines in the event parameters or anything else is missing and so far I must say Daewoo has been faster to respond and has provided more information. I'm still waiting on Mori to try to get some installation drawings.

Let me know if I can help.

I have machined quite a bit of API stuff on Okumas and our Deawoo Puma 10HC 75mm bore. With a big chuck on the Okuma we were limited to 1000RPM also and it was a pain for drilling just too slow. The rest of the machining will go fine as for 2 7/8"API I would thread at 600 to 700 RPM and slower for the larger sizes.