Manual chuck on CNC lathe?
We aquired a second hand Mori Seiki CL machine a few weeks ago. This is our 11th Mori so we are quite familiar wth how they work etc.
The machine came wth a collet chuck attached and a bar feeder, whch we have been running for a few weeks,but we now want to put a 3 jaw chuck on the machine.
The machine was delvered wth a ROTA-G 200-62 chuck. I have looked at these on the internet and it is described as a manual lathe chuck. It has no internal thread to screw it onto the machine draw tube,but can be screwed on to the face plate with 3 cap head bolts.
The hydraulic pedals don't open or close the jaws because they are in no way attached to the drawtube, but instead the jaws are closed with a square key, just lke on a manual lathe, and move in on a spiral.
I certainly don't lke the look of this, or the idea of usng it on the CNC machine, has anybody used one of these on a machine before,if so, did it work? I don't like the idea of the machine spinning at stupid revs, without hydraulics holding the job in the jaws.
On the real big girls all your gunna git is scroll chucks.
For instance - I have a machine with a 32" three jaw Cushman scroll chuck. Now the machine does have a "power wrench" that is nothing more than a gearmotor with a special end on it to mate with the pinion on the chuck. There are also three trq settings as well - but once it's tight - it's tight. Machine will spin 800RPM with that chuck on it.
Hydro can fail - although actuators have check balls (valves?) in them to resist opening from power failure - the scroll will not open w/o turning that pinion backwards.
I have a sister machne with a 15" 6 jaw scroll chuck on it.
I have a 12" scroll chuck that I will put on the smaller machines as needed.
I don't know what to be scared of - other than change itself.
Think Snow Eh!
What machine are you running a 32" chuck on ???
As far as the original question. Yes, I've seen quite a few large CNC machines with big manual chucks, so I believe that it is quite common.
We've got a local machine shop here that ordered a rather large (24" I think)
Haas cnc lathe with a manual 4-jaw on it.
As he explained, the work he does is very low volume (1-8 parts), for
powerplant overhauls (time constraints) and the cnc is needed for
the various contouring of the complicated parts.
The cycle times are pretty long, the materials are pretty tough,
the load/unload time is a very small percentage of the total.
Bison 16" 3 jaw scroll chuck on a 24" swing lathe. 1800 RPM machine. Torque limited impact wrench. No problems.
Haas toolroom machines use manual chucks and we use either an 8" or a 10' on a Haas GT20 which works fine. It is possible you will need to derate your maximum rpm but maybe not depending on the rating for the manual chuck.
Originally Posted by turner13
I think your concern about lack of hydraulics holding a spinning chuck closed is misplaced. A hydraulic chuck can open at high revs because the closing system can back drive; it is only a wedge system and does not have any mechanical lock. A scroll chuck cannot back drive open due to centrifugal force.
Manual chuck on CNC lathe?
Once you get to a certain size, the chucks are usually manual.
Often they are 4 jaw chucks, because the parts need to be indicated.
As far as I can see, they hold as well as any hydraulic, as long as you actually tighten them.
Take a look at a nice picture I have on the website, we are making a oilfield motor housing on a large CNC lathe and we are using a large manual 4 jaw chuck.
I'm certainly enlightened. Thank you men.
I look forward to trying "something different"
Go to the Schunk web site download and view the anamation on how it works...that chuck is not a scroll chuck at all. It is manual but the closing action works with cams and sliding (as linear) tooth plates. The jaws are quick change and can be reversed by just turning them around. Much higher gripping power than any scroll chuck, and higher accuracy due to the linear sliding elements not changing diameter as the jaw moves in as a scroll chuck does.
That manual chuck costs about $6K ...one of the nicer work holding devices you will encounter, and the quick change jaw feature is very nice.
If you don't want it PM me .....Just bought a similar one for my CNC Romi
I bought a Methods Slant 50 once where previous owners removed the hydraulic chuck + draw tube, and installed a manual chuck simply because they needed a little more thru the chuck bore.
Unfortuntely for me, the morons (Kennametal plant in SC) *lost* the original chuck, tube and closer. In the end I came out ok anyway, but how frustrating knowing that somewhere in the Kennametal system was sitting a brand new Kitagawa chuck, tube and closer and yet no one could find it...so it probably got scrapped !!
If its any help, have a look at the link below.
They have a bucket full and would always talk a deal!
Originally Posted by AlfaGTA
Sounds like the ITW Woodworth Ball-Lock chucks I'm familiar with. They actually grip harder with more rpm. The jaws rotate on a ball a with a counterweight opposite the jaw.
They are somewhat self centering and can be actuated by a drawbar. The grip range is smaller than a scroll chuck, but better than a collet. They work really well for high speed machining of castings like brake rotors.