Advanced Analysis and Vibration Reduction

Dynamic Balancing

Determining whether a rotating mass is out of balance can be simple, however vibration that “feels” like unbalance may not necessarily be from mass unbalance.

On more than one occasion we have been called out to “balance” a rotor and found that there really was no mass unbalance, but rather a loose pedestal, or soft foot condition allowing the machine to vibrate at its rotating frequency.

Several things can contribute to vibration that acts like unbalance such as loose bolts, cracked foundations, misalignment, locked isolators (opposite of soft foot), soft foot, worn pulleys, etc. There are also causes of unbalance that are very easy to correct such as dirt within pulley cavities or dirt or grime buildup on rotors.

What is left may be mass unbalance. Our technicians will diagnose whether there is mass unbalance by looking at the FFT, checking phase (direction of vibration), and inspecting the entire machine. If unbalance is found, we can place weight or remove weight depending on the situation. We will also take vibration readings on all bearings, analyze and provide a report on the complete condition of the equipment.

Laser alignments performed with the latest state of the art alignment tools.

PdM Specialists has the best tools on the market with experience performing hundreds of alignments (horizontal, vertical, train, etc.) on Pumps, Gearboxes, High Speed Compressors, Off-set shafts, and more. We can get your machines aligned faster and follow up with vibration testing at a very competitive price.

Our all in one services ensure you only have ONE (1) service call to make, saving you time and money! Performing vibration analysis first (if coupled) ensures time will be spent on correcting the right problem. We determine if a misaligned condition exists and correct it on the spot. Most alignment companies can provide you with before and after alignment values, but you have to wait for the vibration analyst to take readings to confirm a reduction in vibration or provide baseline data. Our technicians are certified analysts so analyzing the vibration before an alignment and after is just part of the service call at no additional cost.

ODS Testing

Operating Deflection Shape analysis is another method we use to troubleshoot “why” and “how” vibration is occurring.
Using ODS we can visualize the movement of an entire machine, or diagnose a structural problem. ODS is a collection of vibration readings in reference to each other. The direction and placement of the sensor is critical in determining how a bearing pedestal may be moving in relation to another bearing etc. The typical results found are structural problems (which are identified) and resonance problems.

Acceptance Testing

Having placed into service a 500HP motor and pump the equipment fails two months into operation. What was found was bearing defects on a grand scale. Or, take the 1500HP motor and fan that were in place for less than a year and found with major cracks in the foundation and bearings that were being hammered due to the impacting from the poor foundation.

These problems could have been avoided by having PdM Specialists perform acceptance testing. In the first case, the bearing failure was due to defects that very likely would have been diagnosed during an inspection upon installation. The bearings could have been damaged prior to installation or may have been damaged during the first few months. The 1500HP motor was on a VFD and if tested would have determined that a resonant condition was occurring at 60% of full operating speed – which it was running at for the majority of the time in operation. This extreme vibration destroyed the foundation, and continued to destroy bearings.

PdM Specialists provides Acceptance testing not only for vibration, but also sound. We measure vibration on systems with VFDs to determine where resonance (or each resonance) is, thereby enabling the VFD to avoid that frequency. In many cases sound pressure needs to be kept to a minimum and we have microphone arrays and sophisticated data logging sound level meters that can perform sound measurement testing that can be measured against that of the specs provided to our engineers.