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Matsuura HMC rigidity/vibration issues

JBethell

Member
We have a relatively new (less than 2yo) Matsuura H.Plus-500. While cutting a part awhile back, made of 17-4 H1150 we ran into some vibration issues. The part had to be moved to this machine, from an old 50 taper VMC because of the VMC going down for a seperate issue. I was using an Ingersoll 2.5" High Feed Mill, 300SFM, .40IPT, .040"DOC and 1.5"WOC. The VMC was able to run this cut just fine, with about 90 minutes cut time per edge. After moving the part to the Matsuura, the Matsuura is also able to run this cut just fine, with similar tool life UNLESS you cut in the X+ direction. The Matsuura will start to buck and jump like crazy!! X-, great. Y-, great. X+, blah.

I was able to adjust my parameters, and change my toolpath to avoid X+ cutting, but this is a brand new machine. Why is it able to do it in 2 directions, and not the 3rd?? (I didn't try Y+ because I generally avoid that direction anyways for heavy cuts, since pulling up away from the table isn't exactly optimal) I did adjust all 3 directions to make sure it's climb milling on each one, to keep conditions as similar as possible. Spindle load never tops 30% during this cut. Matsuura has been out, and they checked the ball screws, and pre-load bearings and they say everything looks good.

The part is held on an Orange Vise Tombstone, with small dovetail grooves cut into the stock, which are engaged by large talon grips in the vise jaws. Because of the fact that cuts work in 2 directions, I'm inclined to believe that the tooling, cutting parameters, workholding, and spindle are not the problem. Matsuura is coming in, again to check it out. Does anyone else have any input as to what we could look for to resolve this issue? It's been going on for awhile now, and I'm tired of working around it!

Thanks for any input!!

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rklopp

Active member
Is there something funky going on with the rotary, like backlash that closes solid when pushed in one direction but is loose going the other? Is the rotary supposed to lock when not in use? What's the distance from the cut plane to the center of the rotary axis?
 

Garwood

Active member
Gibbs/ways loose?

I had a CNC lathe that was fine unless you turned in the direction that lifted the turret. Found the bolted on part of the Z ways and the gibb was loose.

Lack of lube, like a broken way lube line, can show up in finishes too.
 

johansen

Active member
Can only guess that some bolts have loosened up. spindle tram needs to be checked at a minimum.

does this machine use linear rails or ways?

you may need to apply hundred or even thousand pound force to the machine before you can measure where the slop is and where its coming from.

For example, a VMC with 6 bearing blocks and 2 rails for the spindle. you could remove the bolts completely from any 2 bearing blocks and still measure zero backlash, and minimal slop with moderate hand pressure on the spindle. Loosen all 3 blocks on one of the rails and you will be left with only the over constrained bearings on the other rail to stabilize the spindle, but with only moderate pressure you might not measure much slop and you might conclude the bearings and blocks are slightly worn out. If the machine wasn't perfectly aligned, those bearings may be cocked at an angle and the spindle is being pushed into those other three bearing blocks and thus appears to be functioning normally! -until you exceed the "clamp load" so to speak.

but take a pry bar and push on the spindle sideways and you'll find its constrained in one direction but not the other.
 

cnctoolcat

Active member
The axis ballscrew thrust bearings could be out of adjustment, worn out, or improperly installed.

This is what could be happening:

In one direction, the cutting forces make the thrust bearing races tight against the balls/rollers, allowing for a good machining cut.

Whereas cutting in the other direction is pulling the thrust bearing races apart, making for terrible cutting conditions.

ToolCat
 

JBethell

Member
Can only guess that some bolts have loosened up. spindle tram needs to be checked at a minimum.

does this machine use linear rails or ways?

This is a linear guide machine, which I understand, isn't generally as strong, but the fact that the cut works in 2 axes keeps popping into my head

That was my first thought also.

Check for soft foot, concrete will settle over time. Each leveling pad should have approximately the same torque applied to it.

The concrete slab was poured specifically for this machine. But that doesn't mean something didn't move, or settle. I will check on that. Thanks!

The axis ballscrew thrust bearings could be out of adjustment, worn out, or improperly installed.

This is what could be happening:

In one direction, the cutting forces make the thrust bearing races tight against the balls/rollers, allowing for a good machining cut.

Whereas cutting in the other direction is pulling the thrust bearing races apart, making for terrible cutting conditions.

ToolCat

I will mention that. The Matsuura techs did take the ballscrews out to check them, and the preload bearings at one point. Not sure if that would have been evaluated at the same time? (I don't know much when it comes to getting behind the sheet metal, I'm just a programmer/machinist for now)

Have you checked the spindle tram ?, maybe the backside of the cutter is rubbing ?

I'll check that out. I have not yet. However, from the vibration pattern, it appears that the front is leading, like it's leaning the tool. But, doesn't hurt to check!!

Is there something funky going on with the rotary, like backlash that closes solid when pushed in one direction but is loose going the other? Is the rotary supposed to lock when not in use? What's the distance from the cut plane to the center of the rotary axis?

B axis is hydraulically clamped during the cut. The cut is about 8 inches up off the table.
 








 
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