1S7: (90 min.) Just because Unbalance is the most common vibration problem it isn’t always so!

John van Zwienen, Trainer & Technical Advisor


It is widely recognized that Unbalance is one of the most common vibration problems affecting rotating machinery. However it appears that this fact often gets in the way of properly diagnosing vibrations that occur at 1X running speed frequency. Many times a balance effort is started after the vibration on a machine is measured at 1X Synchronous Frequency and only when this does not deliver the expected results other possibilities are considered.

Vibration Analysis work requires a good knowledge of the fundamentals of rotor behavior. Knowing what the expectations are with regards to Synchronous (1X) motion of the rotor should be the starting point of any analysis of any vibration problems. This means that as much data and information as possible should be collected and used to consider all the factors that can affect the synchronous rotor response.

This presentation is based on the author’s recent experiences where he was requested to assist with balancing work and none of these cases actually proved to be a balancing problem.
In all cases high 1X Vibration amplitude was measured and in all cases balance work had been attempted but did not produce the expected results.

Proper knowledge of Fundamental Rotor behavior coupled with collecting enough data/information to compare against “what is expected” should allow analysts to make clear distinctions between unbalance and other 1X vibration problems.

Using the simple 1X = Unbalance approach is a gamble with pretty good odds. However for high speed critical machines which are often the main ‘money makers’ in a plant, taking risks should be avoided as this approach can become VERY expensive. Proper analysis, of what appears to be a fairly simple and common problem, is required to avoid costly mistakes.


John is a Dutch citizen who has been based in Indonesia for the past 25 years. He currently serves as a Technical Advisor and Business Partner for a local company.

Before moving to Indonesia in 1993 John held positions as Service Manager and General Manager for South East Asia for a leading private US based company involved in Rotating Machinery Protection and Diagnostics Systems and Services.

The Entrepreneur in him led to a venture into Indonesia joining with his Indonesian partner to start a company and represent his previous employer. Since then this company has taken on several high tech multi-national companies that now rely on John’s experience, knowledge and skills for their representation. The business model of the ‘Local Subsidiary’ of these niche businesses has been providing products and services to the various industries in and around Indonesia.

John studied Electrical Engineering in Rotterdam before embarking on a career as a Rotating Machinery Specialist. Throughout his career he has continued his education in the technical.  He is also a Certified Category IV Vibration Analyst.

John has extensive International Management and Marketing experience and an understanding of a wide range of technologies which he uses to provide the company with direction and support on a regular basis.