How to make vibration analysis work to perfection

In some cases, the use of applied diagnostics does not produce the expected end result. For example, a company may purchase a vibration analysis system and provide proper training to its staff, but still not get the expected results from its use.

THERE ARE a number of factors that can cause the vibration analysis being used to be ineffective.

Vibration analysis requires proper knowledge

The goal of vibration analysis is to receive the information about the current machine condition and decide if the condition is good, or if some repairs or adjustments need to be made. First of all, it is crucial to train the maintenance staff who will be using the vibration analysis equipment. Vibration analysis is definitely a scientific discipline. However, this does not mean that the person using a vibration meter needs to have a deep knowledge of its theory! Obviously, when we train the maintenance staff who will be responsible for vibration data collection and basic data trending, they don't need to know about advanced data analysis such as orbits or similar issues. It is important to provide the appropriate level of knowledge and training. However, the person using an advanced vibration analyser should have advanced knowledge. It is not enough to buy an expensive professional analyser if we do not have someone who can understand the measured vibration data.

Vibration analysis is in some ways similar to medicine. A vibrometer measures the overall vibration level, much like a thermometer measures body temperature. It doesn't require much knowledge for the user to read, interpret and trend these readings correctly: Either the machine/person is fine, or its condition is slightly worse, or it is very bad... The subsequent analysis of the vibrations with the vibration analyser is then similar to the evaluation of X-rays in medicine. Some things are obvious and visible to almost anyone, but further evaluation depends on the experience and knowledge of the doctor.

Communication between maintenance staff and vibration analysis team

Different companies have different organisational structures. However, the following scheme is common: vibration diagnosticians collect and evaluate the data, and mechanical maintenance staff take care of repairs and other machine treatments. If the communication and data transfer between these two teams does not work properly, it will inevitably lead to poor results.

Communicating and understanding data is essential no matter how your organisation is structured. If decision makers do not have sufficient information, they will not be able to make the right decision. Correct advanced vibration analysis is worthless if it remains in the hands of those who cannot take any further action or make any decisions. Moreover, machine condition reports should be accessible throughout the company to all those responsible for the machines.

Proper customer service

After sales service is essential. When you buy an expensive professional vibration analyser, you need to be able to contact someone who can answer your questions and provide you with sufficient information and training.

Different systems have different functions and controls.

It is important to know how the system you have purchased works and to be able to send questions directly to the producer and get an answer. Unfortunately, manufacturer contact details are not always available nowadays.

The Human Factor

The human factor is definitely one of the most important influences on the efficiency of vibration analysis. The best situation is when the person responsible for the vibration analysis is also the person who is interested in it. Vibration analysis is a fascinating field and a personal interest can greatly increase its efficiency. The more the person knows and cares about the machines, the better the diagnostic results will be. If vibration analysis is given to a person who already has a lot of work to do (usually an electrician), without an increase in salary, the results will be poor or non-existent.

Right system purchased

Sometimes companies purchase a high quality but inappropriate system. If the decision to purchase a new diagnostic product is left solely to the finance department, which only has a list of required functions, the wrong decision may be made. Only someone with the appropriate knowledge can make the right decision. You should also consider the skills of your staff before buying a system. You will not get the results you expect if you buy an advanced system for someone who will never learn how to use it.

Correct use of vibration measurement equipment

It is necessary to use vibration measurement equipment according to rules that ensure correct signal transmission between the machine being inspected and the vibration measurement equipment. If not, we may get a wrong reading; even an experienced diagnostician will not be able to read the information that is simply not there. For example, measuring points are very important; we need to choose the right ones and prepare them properly. The best solution is to use measuring pads and stick them to the measuring points. This ensures good signal transmission and repeatability of measurements.

Communication with an external vibration analysis service provider

All of the above reasons describe the situation when the company itself takes care of the applied vibration analysis. The other option is to hire an external company to provide diagnostic services. In some cases this could be a good solution, especially in cases where we know that we are not able to ensure all the factors mentioned above. However, this does not automatically solve all the problems. In this case, communication between the factory and the service company is essential. Both groups need to work as partners and discuss the findings and recommended solutions. Steps recommended by a service company should be taken, otherwise the services are worthless. There is one disadvantage to using an external service company that is not easily overcome, and that is the fact that they don't know the machinery as well as the people in the company. In order to reduce this factor, the plant personnel need to say and report what they experience and see on their machines. A typical example of poor communication is a situation where the maintenance staff have carried out a machine repair and no one has informed the external service company about the repair. Then the external service company stares at the new measurement and tries unsuccessfully to find the reason for the change in machine condition.

Conclusion

You may think that all the reasons listed above sound quite obvious. In practice, however, we see that it is not so easy to fulfil them all. Unfortunately, the mistakes listed can lead to the false conclusion that the vibration analysis methods themselves are not working. The company may blame the method for not working as it expected, but in this case the problem is just incorrect application of the method. Correctly applied vibration analysis is definitely worth doing and is a very effective part of a predictive maintenance programme.