Forum help

Kindly send both DE & NDE (horizontal side acceleration reading kindly send m/s2.

Hi,


Please share the following data to analyze 

Previous data and current 
Data Must have H,V and A, Phase data 
Plots available , make a link.... Spectrum,  others orbit 

It appears the highest amplitude frequency is associated with turning speed. Is that correct? Collect an axial reading as well, since this is essentially an overhung rotor. 

Also record comparative phase data in the axial direction at each bearing at 90 degree orientations. Phase differentials will define the condition as either unbalance, resonance, looseness, or other events that occur at the 1xTS frequency.

Bad design. Decouple grinding wheel from motor (Lovejoy coupling or similar and alignment is extremely important) – mount grinding wheel on appropriate spindle that uses matched set of vectored thrust bearings (spindle oiling and preload is important) – change bearings in motor as you likely damaged them – certify everything to one tenth of one one thousands of an inch. Electric motors used as machining spindles ought to be avoided…

Since we have data from a single point in time, we do not know if this condition is new or whether it developed suddenly or gradually.  That would be very important information.  We don't really know anything about the stiffness of the motor support structure.  I would start with simple things first.  Check all the motor mount bolts and ensure they are all tight.  Check the entire support structure for any loose bolts or cracks in the structural components.  Check the grinding wheel for any evidence of damage that might result in an imbalance.  Check the mechanism by which the wheel is secured to the shaft for wear or looseness.  The photograph quality is poor.  It appears there is a coupling present.  Check for any evidence of damage or loose bolts.  If this coupling requires lubrication, check that the lubrication is adequate.  Next, perform a coast down and continuously measure and plot vibration vs RPM.  If it drops with motor speed, try to balance the grinding wheel.  If it drops far faster than motor speed, there is a resonance, likely due to looseness somewhere.

Balance that Wheel with a "Bubble Wheel Balancer"

You need a Vibration guy like@Stephen.
Please let us know if you find unbalance, resonance or others.

It is a little difficult to see, but it looks like the base is not particularly rigid (I would also see to a fan cover).  With limited information I would think that a small unbalance in the wheel may be generating what you are seeing, especially with the DE and ODE sides being out of phase.  Lower vibration on the DE side would be basically 'wagging the dog' if the base is more rigid on that side and the wheel is out of balance - basically a pivot point - which is enforced by the data showing a prominent 1X.  Do you have a better picture of the base?  Or have you replaced the wheel?

Couple (moment) unbalance - tends to cause a 180° phase difference. You have to do two-plane balancing.