×
INTELLIGENT WORK FORUMS
FOR ENGINEERING PROFESSIONALS

Log In

Come Join Us!

Are you an
Engineering professional?
Join Eng-Tips Forums!
  • Talk With Other Members
  • Be Notified Of Responses
    To Your Posts
  • Keyword Search
  • One-Click Access To Your
    Favorite Forums
  • Automated Signatures
    On Your Posts
  • Best Of All, It's Free!
  • Students Click Here

*Eng-Tips's functionality depends on members receiving e-mail. By joining you are opting in to receive e-mail.

Posting Guidelines

Promoting, selling, recruiting, coursework and thesis posting is forbidden.

Students Click Here

Jobs

VFD CREATING TRANS NOISE AND VIBRATION?

VFD CREATING TRANS NOISE AND VIBRATION?

VFD CREATING TRANS NOISE AND VIBRATION?

(OP)
We are battling some odd whining noises and vibration in a machine tool.  All issues have been isolated to the motor/trans  assy which incorporates one motor standing vertically with a heat shrunk gear going into an Al gearbox with straight cut gears to provide 1 speed ranges.  There is a total of 3 gears in the trans plus the one mated to the motor.  

Vibration can easily be heard and felt and is making it into our part finish.  Has been this way for the 3yrs that we have had it but has not seen to got any worse.  Vibration amplitude seems to be strongest from the motor but our test devices have been unable to pinpoint the exact frequencies and amplitude but fair to say with our testing that it is in the 40-100hz area.  Seems to increase with motor rpm and presents vibration but not as much noise in low range.

Drive is an old Magnatek open loop drive. Drive is likely 15yrs old.  Never had a single issue with it though.  We do have our monitor go whacky every time the spindle accelerates, which we still cannot pinpoint.

http://www.youtube.com/watch?v=qQ9pWDc3hyY
I did not have an audio recorder on hand so I grabbed the camcorder.  Please excuse all the background noise.  There is also an audible thump on decel that we just cannot put our finger on.  Sounds like a belt thump.  Has done it for years.  

Any help or ideas would be appreciated.  We have been in the trans once looking for this ghost and surprised to find a rather nice looking trans.  Gears look great, bearings were in good shape but we could not really test them.    

RE: VFD CREATING TRANS NOISE AND VIBRATION?

This is a problem that has been known for years. You are lucky if you haven't had in a machine so far.

It is all about the PWM waveform delivered from the drive. Google PWM and drives to learn more.

The standard remedy is to increase the carrier frequency, aka switching frequency. By doing so, you move the vibration up in frequency as well as moving the whining sound into a frequency range that can't be heard.

Look in the inverter's manual how to do it. Or get your supplier on site to do it for you.

What drive is it? I may have the procedure in a manual on my shelf.

Oh, yes. You may have to make sure that the higher carrier requency is allowed. You sometimes need to improve cooling or something.
 

Gunnar Englund
www.gke.org
--------------------------------------
Half full - Half empty? I don't mind. It's what in it that counts.

RE: VFD CREATING TRANS NOISE AND VIBRATION?

(OP)
Well, we already have another Mits vector drive for the machine BUT we do not have time to dive into that right now.  Right now we need to find the culprit and plan a solution BUT are you saying adjusting the CF could be a fix all or just the whine?  Our primary issue right now is vibration.  I have been studying the manual to figure out how to get it to coast on Estop without braking so I could see if the vibration goes away.  

http://www.yaskawa.com/site/dmdrive.nsf/LEG/MNEN-5JLRL4/$file/TM4231.pdf

here is the manual if you care to help out.  I would really appreciate it.  Been fighting this for some time now.  I am going to be happy and irritated if the drive is causing all of this but my gut says no....  I hope I am wrong.   

RE: VFD CREATING TRANS NOISE AND VIBRATION?

Don't know if it's my connection or not, but that video appears to be blank on my screen, not something I have experienced with YouTube before. Or maybe you just wanted the sound?

If your drive is 15 years old, it may not have the abilitiy Skogsgura mentioned. It may be time to update that system and get a better drive.

"Dear future generations: Please accept our apologies. We were rolling drunk on petroleum."
— Kilgore Trout (via Kurt Vonnegut)
  
For the best use of Eng-Tips, please click here -> FAQ731-376: Eng-Tips.com Forum Policies  

RE: VFD CREATING TRANS NOISE AND VIBRATION?

(OP)
I did not have any video, shudder was shut.  Just trying to get an audio clip real quick.  Jraef, the carrier frequency is 15khz.  If I can somehow prove that the drive is the problem, I already have a nice Mits sensorless unit to put in but need to know where the vibration is coming from.  

Can you hear the intermittent chriping?  There is also some pretty good vibes you can feel throughout the whole machine.  All rotating elements have been disengaged except the trans and motor.  Same vibration in high and low range but no chirping.   

RE: VFD CREATING TRANS NOISE AND VIBRATION?

Listening to that I would in no way expect that to be drive related.   I think you have a problem (in order of likelyhood)

1)gearbox bearing
2)coupling wear/failure
3)bent shaft
4)gear shaft/bearing
5)spindle bearing
6)bent spindle
7)gear tooth
.
.
.
.
.
20)motor balance
.
.
.
.
.
30)drive problem



I would not expect the drive to cause a random-ish chirping noise but rather a much, much, faster vibration.
 

Keith Cress
kcress - http://www.flaminsystems.com

RE: VFD CREATING TRANS NOISE AND VIBRATION?

(OP)
You are the winner!  Changed program on drive to coast down so i sped it up and let it coast.  Vibration is totally mechanical.  Chirping is coming from the output shaft in the trans and i suspect balance issues in it as well.  Good call.   

RE: VFD CREATING TRANS NOISE AND VIBRATION?

Thanks fastline for the come-back.  Always nice to get feedback from our discussions.

Keith Cress
kcress - http://www.flaminsystems.com

Red Flag This Post

Please let us know here why this post is inappropriate. Reasons such as off-topic, duplicates, flames, illegal, vulgar, or students posting their homework.

Red Flag Submitted

Thank you for helping keep Eng-Tips Forums free from inappropriate posts.
The Eng-Tips staff will check this out and take appropriate action.

Reply To This Thread

Posting in the Eng-Tips forums is a member-only feature.

Click Here to join Eng-Tips and talk with other members!


Resources