Sign up Calendar Latest Topics Donate
 
 
 


Reply
  Author   Comment  
MarkL

Avatar / Picture

Sr. Member
Registered:
Posts: 1,120
Reply with quote  #1 
Hi Fellas
I'm starting a new site tomorrow and one machine I've been asked monitor is a rolls section taking hot extruded olyproelyne from the dies into sheets. The rolls are running around 3-5 rpm with a 'herring bone' gear tooth arrangement, supported in spherical roller bearings, readings can only be taken radially. The extruded plastic snakes around the three water cooled rolls.

I'm thinking with the slow speed that maybe twf and gE/envelope acc taken as close to the load zone, are the best things to use as fft at that slow of speed doesn't show much.
Any thoughts.

Many thanks
OLi

Sr. Member
Registered:
Posts: 1,914
Reply with quote  #2 
I would try the 500mV/g sensor anyway and some variations of env. also just in case it would catch something and some current consumption or so at some or more operating speeds depending. Do they break?
__________________
Good Vibrations since early 1950's, first patented vibrometer 1956 in the US.
http://www.vtab.se
marksl

Sr. Member
Registered:
Posts: 150
Reply with quote  #3 
Ultrasound could be an option ?
Big Al

Sr. Member
Registered:
Posts: 102
Reply with quote  #4 
I agree with the above.

500mV/g accel and try to reduce any cable movement. Try out the different envelope filters on your system and see what works best. I use Emonitor and use a 100Hz GSE filter on anything <20RPM.

For a better response you could consider quickfit studs rather than a magnet mount.

On my site, I have all the slow speed stuff on an ultrasound route as well, which gives me a lot more confidence.
MarkL

Avatar / Picture

Sr. Member
Registered:
Posts: 1,120
Reply with quote  #5 
Thanks for the suggestions guys, I had actually tried ultrasound with a contact probe last month and all I was getting was the odd barely audible scratch hut nothing concrete that and my instrument doesn't record decibel level.

I've taken some acc fft and tef readings this morning for 1 minute per bearing and will post process it on Arm software tonight. I have 2 500mv sensors courtesy of Rusty :-) and never thought to try them. I'm currently on lunch and will try some readings after lunch.
trapper

Sr. Member
Registered:
Posts: 77
Reply with quote  #6 
Quote:
Originally Posted by Big Al
For a better response you could consider quickfit studs rather than a magnet mount.


Al, is this what you're talking about? I think they're awesome for that type of work (and also high speed machines). Wish they would let me use them on some of the critical equipment here.

Untitled.jpg 

I agree with all of the above. 

dnk

Member
Registered:
Posts: 63
Reply with quote  #7 
I like the 500m/g And envelope. I like TW for slow speeds, If it isn't in the TW it's not going to be in the FFT. UE also works well.
Noknroll

Avatar / Picture

Sr. Member / Supporter
Registered:
Posts: 843
Reply with quote  #8 
I've had success on 2.4 rpm with 100mV/g. 
Beatnik

Sr. Member / Supporter
Registered:
Posts: 183
Reply with quote  #9 
Ask a lot of questions about the history of those bearings and what they expect from you.

Slow bearing are often hard to change and can still run for some time while in pretty bad shape. If they usually change it every 2 years when it's completely destroyed, they probably won't want to change it after 1 year because of spalling on the outer race.

Also trend the temperature. It helped my in the past on slow bearings.
Noknroll

Avatar / Picture

Sr. Member / Supporter
Registered:
Posts: 843
Reply with quote  #10 
oil or grease lubrication......sampling?
2Per

Member
Registered:
Posts: 4
Reply with quote  #11 
Hi all, im a newbie to this great forum. My experience with slow speed, it appears you’re using skf. I myself use skf and I am successful catching slow rpm faults down to 1 rpm. My advice is not to go with 500 sensor, reason being is that the response is poor on the higher frequency range where I utilize filter 4. Simply go with 100 mvg sensor it has wider response range. Like what most people say here the mounting is critical. If you can have stud mounted, load zone and I prefer axial position on a roller bearing. You will have better chances. Also don’t limit yourself with spectrum. Look at the time waveform and see the peak intervals.
MarkL

Avatar / Picture

Sr. Member
Registered:
Posts: 1,120
Reply with quote  #12 
Thanks for all the great advice guys, I looked at the data last night and got some inner race peaks on one particular 22220. Thanks for heads up on axial readings. Customer shouldn't mind putting quick fit studs on, those are interesting looking ones posted, we use different ones.
Previous Topic | Next Topic
Print
Reply

Quick Navigation:

Easily create a Forum Website with Website Toolbox.