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UMC-500 rigidity and surface finish issues

dcrace

Aluminum
Joined
Jun 26, 2002
Location
U.S.A.
Anyone else with a UMC-500 having some slight issues with rigidity? Seems like even with aluminum if I want to hold any sort of tolerance I am having to add a spring pass to my finishing toolpaths.. Even running basically the same cutting parameters, tooling, etc. from previous runs of the same part in another VMC (moved setup to 5 axis to eliminate part handling between setups).

Also experiencing cutter marks on the floor of pockets, etc when the machine changes direction, these are more prevalent on aluminum parts most likely due to the increased feedrate. I have tried different G187 settings but still haven't completely figured out what's causing these issues.

I completely understand, the machine isn't going to give us the same rigidity as a traditional table travel VMC, but troubling to have these issues on finishing cuts..

Any input is appreciated as I am waiting to hear back from our HFO.
Thanks.
 
The moving head design is more vulnerable to loss of stiffness with movement, and when I good at the structure and kinematics of the machine, trouble with accuracy and finish doesn't surprise me.

I really like the idea of moving head, but getting it right, perhaps even including an active strain element to balance "stickout" in Y become critical, IMO. Bigger rails and bearing blocks, and as wide a spacing as possible between rails really needs to be emphasized.

UMC-500 - What's New! - Haas Automation, Inc. - YouTube about 0:27 - 0:30 for a look a the upper castings and rails.


Edit: With this video of the revised UMC 750: UMC-750 Redesign - Haas Automation, Inc. - YouTube

at 9:00 they talk about the changes to the upper bridge and Y ram, and while you can't make an easy comparison with the structure in the 500, it's clear that they had to address stiffness issues likely the same as what the 500 suffers from.
 
we forced haas to take our UMC500SS back after about 6-7 months due to the NUMEROUS issues we've had with it. from what i understand, we arent alone, and your issues are not news either. :(
 
we forced haas to take our UMC500SS back after about 6-7 months due to the NUMEROUS issues we've had with it. from what i understand, we arent alone, and your issues are not news either. :(

We're looking at the UMC-500 and would be very interested to learn more about your issues.

@dcrace: Are the finishes satisfactory after a spring pass? And is the resulting part "reasonably" precise? In other words, is it just a rigidity issue, or does it run deeper like a repeatability issue?

Are these issues with 3+2 or simultaneous 5-axis?
 
We're looking at the UMC-500 and would be very interested to learn more about your issues.

@dcrace: Are the finishes satisfactory after a spring pass? And is the resulting part "reasonably" precise? In other words, is it just a rigidity issue, or does it run deeper like a repeatability issue?

Are these issues with 3+2 or simultaneous 5-axis?

since the beginning, it made a crazy loud thud every time the machine zeroed. they got rid of it by messing with the offsets, which in turn made the tool changer crash.
affter awhile the main control board went out randomly, took almost 2 months to replace it and after that it started dropping offsets for tools/probe, didnt process the code properly etc.
coolant leaks from everywhere, the sheetmetal design is horrible. chips and coolant flying through the gap in the door.
we had our lawyer send them a letter of intent to sue if they didnt take it back since they admitted the issues were their fault.
 
How much stock are you leaving for finishing? Weaker machine: leave less stock, or just deal with the spring pass.

Also, if you're used to clamping a part in a big 6" table mounted vise and switched to a compact multi-axis vise on a riser, it may behave differently. Even if the vise itself isn't the culprit, it is hanging off the table like a lever.

As for the mill marks in the pockets, what spindle RPM and feedrates are we talking here? Toolholder type/length?

Back when we were making our vise pallets on high speed horizontals, we would absolutely blitz the material. Moving them to a VF5, we had to dial everything back quite a bit, but the quality's just as good - excellent finishes and holding 1-2 tenths on bushing bores. Despite the increase in cycle time, it was a huge net gain by being able to run these parts on a significantly cheaper machine.

Our two UMC500s are arriving soon. I'll have more to contribute after running them for awhile.
 
The machine seems to be repeatable and accurate, If I leave .005 for a finish pass with aluminum, I can expect to be within .001. Tool steel I have to do a finish pass leaving .005, then semi-finish leaving .001 and I can usually hold .001 or slightly better, if I want anything tighter, I have to run a spring pass. We still haven't decided which system for workholding we will be using, so mostly everything has been clamped in a Kurt 6'' vise so fixture rigidity isn't influencing it too much and finish endmills are clamped in Schunk hydro holders. I can understand some deflection with harder materials, but with aluminum being an issue is slightly troubling. I attached a photo of an example of the cutter marks we get on the floor of parts when the machine changes direction.
Finish.jpg

The thud when the machine homes troubles me as well and the tech said it is normal to do that..?
 
The machine seems to be repeatable and accurate, If I leave .005 for a finish pass with aluminum, I can expect to be within .001. Tool steel I have to do a finish pass leaving .005, then semi-finish leaving .001 and I can usually hold .001 or slightly better, if I want anything tighter, I have to run a spring pass. We still haven't decided which system for workholding we will be using, so mostly everything has been clamped in a Kurt 6'' vise so fixture rigidity isn't influencing it too much and finish endmills are clamped in Schunk hydro holders. I can understand some deflection with harder materials, but with aluminum being an issue is slightly troubling. I attached a photo of an example of the cutter marks we get on the floor of parts when the machine changes direction.
View attachment 304788

The thud when the machine homes troubles me as well and the tech said it is normal to do that..?

LOL! i assure you, it is NOT normal! their grid offsets are wrong. when they change them, make sure they recalibrate the toolchanger also, otherwise it'll crash like ours did.
 
The machine seems to be repeatable and accurate, If I leave .005 for a finish pass with aluminum, I can expect to be within .001. Tool steel I have to do a finish pass leaving .005, then semi-finish leaving .001 and I can usually hold .001 or slightly better, if I want anything tighter, I have to run a spring pass. We still haven't decided which system for workholding we will be using, so mostly everything has been clamped in a Kurt 6'' vise so fixture rigidity isn't influencing it too much and finish endmills are clamped in Schunk hydro holders. I can understand some deflection with harder materials, but with aluminum being an issue is slightly troubling. I attached a photo of an example of the cutter marks we get on the floor of parts when the machine changes direction.
View attachment 304788

The thud when the machine homes troubles me as well and the tech said it is normal to do that..?

Unless you are making these by the thousands, and *every single tool* requires a spring pass, I wouldn't sweat it. Probably clipping along with a decent feedrate anyways, so what's one xtra pass< 10-20 seconds...?
 
we forced haas to take our UMC500SS back after about 6-7 months due to the NUMEROUS issues we've had with it. from what i understand, we arent alone, and your issues are not news either. :(

Really interested to know how you got them to do that because I am going through an issue they cannot solve with my ST10 with tolerance moving all over the place 0.4mm at times.

I have told them I don’t want it fixed in my time any longer and want a machine I can have confidence in. Mine only has 26 hours cutting so can’t see what they won’t (had it a while but haven’t done much work with it due to issues and we only machine our own stuff).

Any tips would be much appreciated.
 
Really interested to know how you got them to do that because I am going through an issue they cannot solve with my ST10 with tolerance moving all over the place 0.4mm at times.

I have told them I don’t want it fixed in my time any longer and want a machine I can have confidence in. Mine only has 26 hours cutting so can’t see what they won’t (had it a while but haven’t done much work with it due to issues and we only machine our own stuff).

Any tips would be much appreciated.

Good luck with that. Our ST10Y had 1500 hours or so on it and Haas had to do a complete overhaul on it. $25k later, it was usable again(aside from the random A axis alarm we still get). Luckily after several meetings, we got them to cut the bill in half. But they still won't admit it was a lemon.
 








 
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