In many mechanical systems, vibration and the accompanying failures are a multifaceted problem. Design of a mechanical system is often approached first from a static perspective. Designers are usually very successful in ensuring that their structures are sound when the system is powered off and no parts are moving. When the system is switched on and pieces begin to rotate, new forces and their resulting stresses develop throughout the system. Oftentimes designers do not anticipate these dynamic stresses. The stresses are cyclic at the rate of the rotating pieces. They can cause statically sound structures to fail easily if not anticipated.
The Symptoms of Poor Dynamic Design
We have observed countless examples of failure of mechanical equipment in industry. Here are some of the indications of poor dynamic design:
Cracks in the supporting structures of shafts, bearings, and motors.
Unwanted noise transmitting into inhabited spaces (rattling, shaking, grinding)
Early failure or short service life of bearings, pulleys, and shafts.
Previously well-operating machines that are now unable to reach operating speeds.
Curing Poor Dynamic Design
At HI-TEK our primary process is balancing, yet oftentimes treating the vibration disease starts before we even make balancing corrections.
All structures have natural frequencies. Natural frequencies are the speed(s) at which vibration occurs when a structure is acted on by an outside force. When a rotating machine spins at a speed the same as or similar to the natural frequency, the structure begins to vibrate violently. This dynamic system is operating at resonance. Loud noise and damage is observed in these situations.
Stiffening the structure
The first step to solving this resonance problem is usually to change the natural frequency of the dynamic system’s supporting structure. The natural frequency is determined by the rigidity of the structure. In a small number of cases, reducing the rigidity of the structure is the right option. Centrifuges and clothes washing machines have structures with very low natural frequencies to account for extreme amounts of unbalance that are inherent to their intended function. For the majority of industrial structures, increasing the rigidity (and therefore the natural frequency) is the first step to improving dynamic structures.
We have suggested solutions ranging from very easy to very challenging to solve structural rigidity problems. Welding crossbars to create triangular shapes is a simple way to create rigidity. Reinforcing a machine’s concrete foundation is a challenging way to increase rigidity, though it may be necessary for structures that support very heavy rotating components.
Our Vibration Analysis Services
Full service vibration analysis is the process of examining not just the rotating piece or pieces, but the whole mechanical system. HI-TEK is staffed with dynamic systems engineers that can effectively analyze these systems and recommend modifications to ensure system longevity.
Effective vibration analysis services start with understanding machine design from an engineering perspective. HI-TEK has extensive component design and manufacturing experience. Understanding component design allows us to have unparalleled insight into how those components affect the performance of the entire machine. Extensive in-shop balancing experience, combined with CAD design and ac and dc drive experience has given us a special ability to solve your machinery vibration problems. At HI-TEK, you always get definite answers with clear solutions to your machinery problems, saving you time and money.
Remote Vibration Diagnosis Services
HI-TEK can provide vibration analysis services to remote locations and provide remote vibration diagnostic services. Our equipment is easily portable and our personnel is experienced in using it in remote or hard to access locations. Our remote vibration diagnostic service equipment is battery operated and stores its data onboard. We can provide remote vibration analysis for ships at sea, in areas with tight access, in undeveloped locations, and in rural areas.
Remote vibration diagnostic services save our customers time and money by eliminating complete disassembly and costly packing and shipping of components to a shop for service. In some remote locations disassembly and shipping may not even be possible considering the circumstances. By providing remote vibration analysis we can solve your mechanical vibration problems quickly and easily.
Contact us to discuss your needs.