We have recently taken delivery of a new Multitasking turnmill machine. I don't wish to name the manufacturer so I will just say that our machine is in the same category as Mazak I series, DMG MORI NTX, etc. Two spindle, left and right with milling head and lower turret.
During testing after installation we discovered a problem, and I would like some input from others as to whether this is a common problem or our machine has a serious fault.
When turning a finish cut on the left hand spindle (main Spindle) using the lower turret, we send the milling head for a tool change. We are getting a change in the machined diameter of 0.015mm caused by a combination of the milling head moving and the action of the tool changer. i.e. we have a raised ring on the turned diameter. If we mount a dial indicator in the left hand chuck and place the finger on the turret, then we move the milling head from extreme left to extreme right we see a change of 0.009mm on the dial. If we place a machine level on the turret and move the milling head from extreme left to extreme right we see a change in the level of the turret 0.024/1000. The machine manufacturer sent his installation team back an re-installed the machine a second time with the inclusion of 8 anchors into the concrete foundation to further stabilize the machine. The problem was not improved in the slightest. The machine foundation is new and substantial. So my question for operators of this type of machine is: Is it normal to see the accuracy of parts machined by the turret influenced by the movement of the milling head?
Something is definitely wrong.
Under The Covers Of The Mazak - YouTube
^^^For a bit of integrex "Style" sanity check, check out Peter's youtube video where he adjusts and tightens a few things on his B axis. Machine has a lot of it's covers/way covers off. Nice to see. Check out his use of gauging bar in mill head spindle. (But no lower turret).
Peter's machine is an older style, but the newer integrex (and perhaps smaller) have a very accurate B-axis rotational movement of the head of the order of 2 arc seconds. That's actually one of the most accurate movements of all the machines MAZAK make (just about. Ball bar tests of an integrex for movement of milling head (for example a circle in the ZY plane same as XY plane on conventional vertical mill) is of the order of 3 micron, whereas a more regular but GOOD vertical mill will test out at about 5 micron circularity. Part of the reason for that is the machine only has to travel about 10" in Y max.
So you have a change in level 24 micron in one meter? (when the "Mill" is moved from here to there?). And also 9 micron "Difference" as measured from and between spindle to lower turret when mill assembly is moved from one end to the other ... (Need to do some math on this just to check to check this is not a "Trick" question kind of thing (back in a while lol)).
Even something like a DMG Mori short bed two axis very precise lathe will have wide tolerance band of 40 micron (straightness) over 1000 mm (1 meter) when the simple two axis lathe turret is moved back and fourth, but actually tests out around 18 micron / meter or better (even though it might have a 500 mm Z travel etc.
but the idea that the position of mill head along the Z axis screws up the relative position between left hand spindle and lower turret is a different kettle of fish. But do keep in mind combined errors that are natural to any machine when you get this all "Ironed out".
Some guesses:
1.
Machine is rocking across a diagonal pair of "legs" /feet when mill assembly is moved from one end to the other. This "Rocking" action may be imperceptible but the feet may be unevenly loaded, causing a sort of "Flexing" action in the frame/bed casting between turret and spindle? . On some DMG mori B axis mill turn machines,
this would be nearly impossible as the machine has three legs / feet lol. Guessing MAZAK machine here with lots of feet and a long bed / Z travel.
2. Maybe the machine has been improperly stored for a very long time and has a "twist" in the casting/frame?
--> (I wish feet had electronic strain gauges in them so you would know exactly how the machine weight is distributed, especially over time as a new foundation will settle and move).
Some Questions:
1. What province are you located in Vietnam?
2. Do you have to bribe a lot of local officials just to get equipment and machines into the country ? Can equipment just be sitting on a dock for a really long time?
3. Personally I'm not very taken with the lower turret "Concept" on the Integrex style machines, and don't have any experience of running a mill turn with lower turret... BUT those are supposed to be able to perform "pinch style" operations on shafts for improved dimensional accuracy (theoretically). But also wonder if there is best practice of parking the mill head in a set of consistent locations while using the lower turret ? Which kinda destroys the ultra multi tasking selling point, right ? I have to admit I am skeptical of the whole lower turret and mill head working together kind of thing but Integrex can be a super platform. I remember you mentioned in another thread starter the issue of tool changes whilst turning using the lower turret.
4. How many feet does your machine have and in what kind of layout?
5. How much does your machine weigh/mass of machine ?
5.5 Chuck size and thru bore/kind of turning spindle ?
6. Rough maximum Z travel (Approximately)?
7.
Do you have the inspection certificate for the machine? [As built before it left the factory]. To eliminate factory build error.
8. Have the installation guys noticed any weird "creaking" noises in the bed casting as the mill moves up and down the bed?
9. Is the indicated distance between spindle and turret at a max or minimum distance when the mill head is "parked" for a tool change? (My hunch would be that it would be at maximum out of tolerance distance at the tool change if feet are not loaded correctly; loading frame at that position opens up that distance between turret and spindle? You didn't state +ve or -ve change or how it maps out? ... Just going with the idea that the mill head will have the least influence on the turret and spindle distance when positioned at the far end of the machine i.e. at the right hand side, and the most influence when almost directly across the left spindle and lower turret ? (Maybe) ? ).
10. What orientation is your level in for the turret? Z orientation or Y? turret pitches up and down along Z axis..? Or Yaw; tool goes high and low? Are you able to orient the level "Flat" with respect to ground plane/gravity on turret diagonally pointing to mill tool change position (while mill head is in tool change position)? [You might need cobble together a "Gizmo/fixture" for that].
11. Do you have any plans for metrologists to come in and generate interferometer plots and ball bar tests for your machine? [Proper inspection and mapping of machine; if so you might find how "straight" the machine is versus how it might be "warping" from insufficient leveling.] Might take the guess work out of what's really going on? Or maybe something IS loose and everything else is fine?
12. How many "Integrex style" machines has the installation crew installed before? And have they installed the particular model of machine you have before?
One Comment:
IF moving the milling head and assembly caused such a major performance "Fail" (in general)of the lower turret it would be splattered all over PM forum and the machine would be kinda of "black balled" for that particular failure... So the fact that that specific problem is not common knowledge I would say or "indicate" that there is something wrong with your specific machine... Like what folks are saying here. Foundation not right, or machine twisted from transportation damage or long term bad storage twisting the bed (maybe) or something just loose... not tightened down or build error that factory inspection did not pick up on? [Need to do a bit of "Sanity" math on the measurements you have thrown out there to double check how bad things really are or not].
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Something the MAZAK guys impressed on me regarding Integrex is that it is really a mill that happens to do turning... rather than a Lathe that has a mill strapped onto it. And they then try to stress that mills typically are built to much higher quality than lathes (maybe for MAZAK perhaps, not sure about the scope on that statement in regard to other Machine tool builders etc. ). Make of that what you will :-)