Mori Seiki NV 5000 α1B/50 - Dry Linear Guides
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  1. #1
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    Default Mori Seiki NV 5000 α1B/50 - Dry Linear Guides

    Hello All,
    We just got a used NV5000. Everything works and runs but its was noted the linear guides were dry. Upon a closer inspection, it appears that the linear guides on the X,Y and Z axis are sealed units and only the ball screws and spindle are actively oiled. This seems crazy to me, specifically for such a stout machine. Does any one on here know of the proper maintenance? The maintenance manual only mentions cleaning the wipers. Any insight would be appreciated.
    Thank you!

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    I have a Mori VMC where all of the 6 X axis, and 2 of the 4 Y axis rail bearings/trucks are oil fed from above. Oil lines connect to the table and saddle castings which have drilled passages that empty into passages drilled and countersunk in the tops of the bearings/trucks. The Z axis had oil lines fitted up to the outside bearing end caps as one would expect. It's a VMC swing arm pallet machine which may or may not be responsible for this type of setup. The front of the table casting has a large additional casting bolted up and housing the pallet change mechanisms.

    If you think your rails are dry, maybe you have really good working wipes in your bearing end caps. That or your auto oiler is not functioning properly. Make sure it's pumping oil and that you're using the proper viscosity oil as specified by Mori.

    My 97/98 machine is a high loss machine in the linear rail oiling department. Little chance of not seeing oil even with brand new rails,truck and seals. Maybe they fixed that in later versions. I know a lot of manufacturers have headed toward low(er) loss systems.

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    Thanks for the info 13engines. Ours is a 2004-2005 vintage with the MAPPS II control. I ending up taking all the covers and everything off to investigate farther. I traced all the oil lines from the lube unit to all parts of the machine. The spindle and ball screws are actively oiled but apparently the linear bearings are not. They are sealed unit. Found a part number on the wipers and was able to find the LK bearing truck from that. The X-Axis are THK SHS45. The Y axis are similar.

    I had called Mori to confirm when I first started and they said they were not sure. After my findings I called to complain. Sure enough, they admitted that some of their machines are sealed for life (death) units.

    https://tech.thk.com/en/products/pdf/en_a01_092.pdf

    Now I'm stuck. Anyone have a good recommendation for someone who would be willing to replace the X and Y trucks and rails on a Mori NV5000?

    P.S. If anyone is looking to replace the disc filter for a NV5000 with a Showa pump is F-1301 and can be purchased from RAS Machine Tool Tech.

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    If the rails and trucks aren't damaged, why not run the machine? Or is there noticeable slop?

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    Quote Originally Posted by Milland View Post
    If the rails and trucks aren't damaged, why not run the machine? Or is there noticeable slop?
    I'm with Milland. Unless you're noticing obvious problems, what's the problem? Use-um.

    There are thousands of bearings of all types that are greased for life and are fine like that. Why not these? Remove and clean the end seals if you like, or even replace them if it makes you fell better about things. Don't remove the end caps or the balls will fall out.

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    Quote Originally Posted by 13engines View Post
    I'm with Milland. Unless you're noticing obvious problems, what's the problem? Use-um.
    Unfortunately, they are causing us problems, otherwise we'd happily be making chips oblivious to the issue. The machine is used mainly for roughing now. It appears the machine sat for awhile and the balls wore divots in the rails. Additionally, there was significant rust so I know the balls are damaged as well. The end caps on the bearings are cracked and failing too. Only a matter of time before the balls fall out. Significant slop in the Y axis and some developing in the X.

    Anyone ever source the rails and bearings direct from THK? Also, does anyone have a referral to someone who replaces Linear Guides on machines? Not many techs are interested in the work anymore.

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    I replaced all of the ways on one of my machines. You can't order direct, you have to go through morons, or I always have had to. There are a lot of details to get right but it is doable. I ended up going with HiWin since they were much, much less expensive than THK. Replacing them is easy and aligning everything, ball screws included, is interesting but not too hard. HiWin had the best information on specing and installing guided rails and blocks so I would start there. The rails and blocks are all built to standards so you can replace them with a different manufacturer, they are not all identical so do check every feature if you do.

    If you are serious then:
    1) Price replacements from the MTB first.
    2) If possible find out what accuracy the rails and blocks are speced to? This will help you when sourcing new ones. There are around 7 accuracy levels you can order them at, the tighter the more $$. If Mori won't help you call THK and ask them what the numbers on your rails and blocks mean.
    3) Do you have all the numbers that came off your rails and blocks? They might tell us exactly all you need to know.

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    Quote Originally Posted by imtprecision View Post
    ...Anyone ever source the rails and bearings direct from THK? Also, does anyone have a referral to someone who replaces Linear Guides on machines? Not many techs are interested in the work anymore.
    A few years back I did a ground up on a Mori SV50/40 pallet machine. (I think the SV is the precursor to the NV and/or NX?) New screws,rails everything. Once I had read about every THK bearing book in existence, I created part drawings with all the significant details spelled out. I bet it still took me a week to come up with these two drawings and part numbers. I sent this to THK through a local bearing guy I've used for years. It took three months, but the machine was in a million pieces so I had the time to wait.

    I guess my point is you've got a lot of work to do just to get a legit part number figured out. Meaning dismantling the machine to a high degree to start. I doubt the Mori part numbers would be anything like those needed to order from a private company like myself. The cross drilling on the bearing trucks is not an option you'll find in the books. It's something Mori has them do. Might have been this way on my machine because of the pallet transfer mechanism being in the way. I included the special features in the drawing without asking and they delivered them that way. I'm sure they recognized they were making Mori rails.

    I had the luxury of replacing these rails with all the sheet metal removed. I can't imagine how difficult it would be otherwise. It is very precise and careful work. Let alone the cleanliness part.

    Anyway... I'm proof that it can be done, but it is one hellova job. Also your machine will be down for a good long while.

    If you have the money and not the time, I'd order from Mori, and find someone with experience to put them in. I still think it would put your machine down for most if not all of a week. You'll probably want to laser shoot and ballbar it after you're done too. Doesn't hurt to use brand new mounting bolts either.

    One nice thing about these rails is they're an improved version of the original. Next to highest precision class, improved seal arrangement and rail seals both. The extra length caused by the extra seals did cause me to have to slightly move a couple oil lines and machine away a little of the table casting. I simply figured, I'm ordering... why not get a little more for my money.

    These part numbers include the fancy rail plugs (GC) and additional seals. Note that all the info in these drawings was requested by THK in their literature. (oil use, speed, etc)

    x-axis.jpgy-axis.jpg

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    Having a very good precision level, and a certified straightedge of sufficient length so that you can straddle opposing pairs of trucks while you run them back and forth over the rails (and observe the level for deviation) may be helpful too.

    No matter how good the replacement rails are, there are risks they won't seat exactly the same as the original units, and being able to prove out level and straightness of a rail "system" before adding the next axis would be wise.

    You might also need to adjust ballscrew heights if there's any change in the assembled heights of the linear rails. Such as having to scrape an area to restore straightness, or some other unforeseen event.

    If you go this route, let us know how it progresses.

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    I'm very familiar with the NV5000's, replacing the linear guides on these machines is not as bad as one would think.

    One of the rails will have a "KB" in the part #. That rail is the "master" and mounts to the side with wedge blocks against the trucks. This applies X,Y and Z.

    There is an intermediate shim on each truck that needs to back in the exact same position and orientation.

    As to the greasing, it is possible to add a zerk fitting to the trucks. The plastic end cap can be removed, drilled and tapped for the zerk. The roller balls are retained by a green plastic belt that holds them in place. I don't think it's necessary though. Keeping your way covers in good shape and limiting exposure to coolant and chips will have more effect on longevity than anything.

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    Quote Originally Posted by coolhand03 View Post
    As to the greasing, it is possible to add a zerk fitting to the trucks. The plastic end cap can be removed, drilled and tapped for the zerk. The roller balls are retained by a green plastic belt that holds them in place. I don't think it's necessary though. Keeping your way covers in good shape and limiting exposure to coolant and chips will have more effect on longevity than anything.
    I'd keep the plastic belt - it's to space the balls and prevent them from rubbing during movement. If you do remove the belt you should buy additional bearing balls of the correct (to millionths) size and repopulate the truck to capacity (minus one ball).

    On the plastic endcaps - I'd be really tempted to reverse engineer them and remake them from AL or some other more robust material. Then no worries about blowing them out if you accidentally push too much grease in.

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    Quote Originally Posted by Milland View Post
    I'd keep the plastic belt - it's to space the balls and prevent them from rubbing during movement. If you do remove the belt you should buy additional bearing balls of the correct (to millionths) size and repopulate the truck to capacity (minus one ball).

    On the plastic endcaps - I'd be really tempted to reverse engineer them and remake them from AL or some other more robust material. Then no worries about blowing them out if you accidentally push too much grease in.

    I might have worded that better.
    I didn't mean to suggest that the green belt should be done away with, only that it holds the balls in place when the end cap is removed.
    I never noticed any longer life out of those with the zerk fitting added.


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