hydraulic pump noise

We have a Parker submerged-type hydraulic pump making an 88 decibel racket on a newly acquired Quick Turn 15. We would definitly appreciate your tried and true solutions to reducing noise from that kind of pump.

Wow, is this a used machine?

Cavitation makes a pump noisy, as would a pump roughened up by pumping contaminated oil. Any indication of grit in a filter, or a plugged filter?

Hmm, what else, an mal-operating relief bypass valve (broken springs, whatever that allows it to operate at an abnormally low pressure) might contribute a bit of noise, too.

Just a bunch of WAG's

Used machine. Oil is clean and full. New filter. Pressure is normal. Pump area was filthy from an apparent prior leak when we got it. Might have been run dry for a while; no definitive clues yet. The relief bypass valve is submerged with the pump. Putting an earlobe on the end of screwdriver with the tip on the tank gives a sound that suggests a high pitched rattle sounding something like a piston flying back and forth. Definitely not smooth; could be the relief valve.

I had the same problem once and not sure if its the same style but ended up being a Love Joy
type copuling in there that needed replacing.

Is the air bleed out of the system? Sometimes
air in the lines will create a racket, another
semi-simple, stupid suggestion.

I would check out the air bubble end of things. Sounds like it wasn't properly "primed" after putting a new filter on. Plus since it is a new filter it might not be the right filter so it might be starving the pump for the volume it likes. That also can make for a noisy pump with a plugged filter noise. Otherwise check out its mounting in the tank. Not familial with its type of mounting to keep down vibration but if it is loose vibrating metal on metal somewhere you might be hearing that.

Husker

Orbea,

It does have a Love Joy coupling. It looked good when we cleaned and refilled the tank just a few operating hours ago. But, the Love Joy did not have full contact on both halves. Think that could be it?

Dualkit,

Thank you for the thought on the air bleed side of things. What is the best course there? Just take off a pressure line to the chuck actuator and run it down the tank?

huskermcdoogle,

It could be starved. Don't think it is the filter because it is a common Parker filter. We had replacement supplies on-hand for other applications in our shop. It is not a particularly low micron type of filter. Could have some other oddity in the supply line. I will look for flow quantity when I do the bleed check sometime early in the forth coming week.

Thank you all for your interest and thoughts. Has anyone ever had to replace the gears or other mechanical components in a pump for noise reasons?

[ 09-17-2006, 06:31 PM: Message edited by: outbackmachinist ]

Just a wild shot here - we spent some time chasing a pump noise, and it turned out to be the motor bearings. The motor made an awful irritating squall when hooked up but sounded OK when unhooked from the pump so we ruled the bearings out at first.

It needs to have good contact otherwise it will make that noise. We replaced them and then ran fine. We got them from Local soucre. I my have the part# if you need them.

I run a qt 15 and we replaced the coupling a couple months ago never made any noise just quit working. (lost the keyway on the coupler)

These suggestions are fabulous. There is nothing liking bringing the experience of "been there - done that" to bear upon a problem.

Mudflap,

Following your suggestion, we will definitely revisit the motor bearing issue.

Orbea,

I think that the spider in our Love Joy is in great shape, but we will definitely adjust it for full contact as soon as we pull the unit out again and open it up. Thank you for your follow-up on this thread.

Chipmaker 77,

Your keyway issue makes me wonder why we don't have full contact in the Love Joy coupler. Could be that our machine is experiencing slippage in the keyway caused by key and/or keyway failure. Will examine. Thank you for your suggestion.

The suggestions from all of you have totally reprioritized our planned search for the cause. Prior to the experience that you have offered, we were thinking ratty gears and pretty much only ratty gears. You are opening up our eyes.
Thank you one and all.

Is there any chance the pump is sucking in air on the intake side of things. Usually this would make for foam in the hydraulic fluid but maybe you can't see the bubbles before they go away.
Any restriction on the comes into side would cause excessive noise. I would check out the pressure relief valve. Vary the pressure and see if that has any effect. I found two pipes very close together, vibration caused all kinds of racket. Moved one of the pipes, noise went away all was good. Aint hydraulics fun.
Regards Walt.

An Interim "AFTER ACTION REPORT"

We are now down to 77 Decibels about 3 feet from the pump/hydraulic power unit. Here is what accounts for the reduction thus far:

1. The LoveJoy coupling: Switched from a very hard synthetic spider to a softer Buna rubber spider and closed the gap between coupler halves.
That knocked down the noise by about 10 Decibels.

2. The motor bearings: Changed out the bearings and in the process found that the last guy to do that had put the wavy washer that tensions the bearings at the wrong end of the motor. The old bearings did not seem bad but the whole process brought down the noise one more Decibel.

Other things that we checked:

1) Flow and Air Bubbles: In order to see the flow we put the return line down the semi-clear tube from the chuck actuator. The flow looked clear and consistent with what you would expect from a low volume (5.4 gpm), low pressure (500 psi) hydraulic pump. No air bubbles and no apparent restriction, though we did not measure the actual flow rate with a bucket and stop watch.

2) Connections and other sources of "harmonics": Did not find any that we recognized as potential. No pipes touching. The bell-housing connecting the pump to the motor is attached to the tank lid with the lid being between the motor and the bell housing. Good source of harmonics there but it is part of the design and we did not see much that we could do about it.

Surprises:

1) The pump is not a gear pump but rather a Parker PAVC series Variable Displacement Piston Pump. Parker's own literature says that, when brand new, these pumps kick out 75 Decibels measured 1 meter from the hydraulic unit. Does not look good for further reduction of noise without employing some noise reduction tricks, say, for instance, foam padding on the tank lid and side walls. It is not the sound volume that is so terribly bad now, it's the pitch. It is more annoying that a gear pump by far.

Thank you all for your contributions. They really helped streamline our investigation and solutions to this matter.

Any tricks out there for further noise reduction?

Hi outback machinist,
I've got (2) Mazak QT15's, and yes, even in good condition, the Parker hydraulic pumps are a bit loud. I have a QT20N with a Nachi pump, and it is much quieter than the Parkers.
One thing i've learned over the years is that most shops do not change the hydraulic oil in the machines often enough. Mazak says every 6 months...I think this is a bit too soon. I try to change the fluid every 12 to 18 months.
People think because the system has a replaceable filter that the fluid will last forever. Hydraulic fluid is in constant contact with the air at the top of the fluid inside the tank, and the fluid will absorb some moisture over time. Plus, tiny metal wear particles can find their way into the oil.
I guess my point is if the previous owners of the machine didn't change the hydraulic oil (some shops NEVER change the oil), your pump may have some wear issues, causing a little more noise.
One thing you can do is drop the main system pressure just below the green arrow on the main system guage. Sometimes Mazak has the main pressure set slightly above the arrow, but this is inefficient and unecessary.
One more thing, the electric fan mounted above the hydraulic unit can get pretty noisy as it gets older. You may want to get a new, quiet, fan for the old one. I've replaced mine with much quiter fans. Also, the electric fans on the rear of the machine for cooling the electrical cabinet can get noisy with age.
Otherwise, the Mazak QT15 is the most common cnc lathe ever built, and is a rugged workhorse of the cnc machine shop world. I wished Mazak still made this machine...instead of the Nexus (i.e. Cheapus) series.
Good luck,
Greg Hale
Onwer
CNC Tool Corp.
Abingdon, VA

cnctoolcat/Greg H.,

Thank you very much for your post.

We also have a Nachi pump on a different Mazak. From the same distance it is now about the same in Decibels. But . . . the pitch is different and far less irritating. For now, for us, it is earplugs on the QT15.

Lowering the pressure is a great idea. We are at about 580 psi here; our electricity is a little hot. Looks like a three man job: two to pull the lid up with all its weight and one to adjust the pressure. Probably several iterations before success. For that reason alone it is likely rarely done.

Wear issues are a high probability. The machine came to us with what appeared to be new oil but we changed it anyway. The looks of the tank top and motor told another story. We had to scrape the crusted gump off with razor blades!

Cavitation was suggested in a prior post. Could be that "moisture" in the oil accelerated cavitation in the pump parts. There are little ball and socket connectors at the end of each piston. Beautiful source of potential rattle, especially if worn or pitted.

Yes, the large computer type fan above the hydraulic unit is pretty darn noisy. Will look for a replacement in my electronics cataloques.

Thanks again for your suggestions. What do you make at CNC Tool Corp?

Hey outbackmachinist,
I'm a 1.5 man cnc shop here in sw Va. My main customer makes industrial greasing equipment. I machine several parts for them from barstock. Mostly lathe work, with some milled features.
My customer has a huge machine shop...I get the work because they can't consistently hold the quality. A lot of big plant's support personal tend to be overworked or underqualified, thus the overall quality of the parts is less than can be done by a small, agile, expert machine shop like mine.
I have (2) 1988 Mazak QT15s, (1) 1985 QT20N, (1) 1985 QT10N, (1) VTC 16-B, and (1) 1998 Daewoo Lynx 200A. All my babies are paid for! I sold the Mazak I started the shop with, a 1997 SQT15. The spindle was getting louder with time, and I didn't want to put $13K in an exchange unit.
I have found the older Mazak's to be excellent machines. They are just as accurate as newer machines...just not quite as fast. Reliability is excellent if you take care of them. Mazak and Mitsubishi provide excellent parts support. From a mechanical standpoint, the older Mazaks are built more robust and solid than the newer, Nexus machines.
Good luck with your QT15,
Greg

Greg/cnctoolcat,

I am still working on the cooling fan issue that you brought up. Ours is at about 67 dB A; the lowest I have found advertised is 52 dB A. Mazak's has metal blades; the low dB A ones are all plastic. Cooling fans tend to accumulate a little airborne coolant; don't know what that will do to the plastic overtime but am going to try it.

Congratulations on your niche, machine assets, and independence! I bought my first CNC about 3 years ago - mainly because I am getting older and our product had so many design and setup variations that I thought that I should get something that could "remember" it all. Best money that I every spent in business.

I inspected my first Mazak in Chicago in what the salesman told me was the nation's largest business park. It was enormous; lots of single bay and double bay warehouse/office setups in an attractive layout.

It was a warm day and all the bay doors were up for ventilation. What amazed me was almost every single bay was filled with from one to six CNC's with owner/operators attending to their work.

That was a snapshot on the new industrial America. It is everywhere from the outback of Oregon to the land of Thomas Jefferson; men [and women] caring intently about their machines and the quality of their work. Quite a difference from the days when capital was all amassed in large factories with a horde of 8 hour employs walking through the gate.

In appreciation,

Greg B.

Hydraulic Pump Noise

Hydraulic Pump Noise (Power Pack noise) - YouTube
Can you have a look at this video, there is a sound coming from the pump or motor when i switch off the motor.
If you have experienced such sound before, kindly help me out.

Hydraulic Pump Noise (Power Pack noise) - YouTube
Can you have a look at this video, there is a sound coming from the pump or motor when i switch off the motor.
If you have experienced such sound before, kindly help me out.