(90 min.) What You Should Know When Requesting Workshop Dynamic Balancing

John Manson, Managing Director, Machinery Vibration Specialists Aust P/L


Most engineering departments in the industry know that rotor balancing is important but few have the understanding
of defining what they require the balancing shop to do. They rely on the balancing shop operators to guess what they should do with their rotor.
In this Presentation You will Learn ———–
1. The fundamentals of rotor unbalance.
Causes and symptoms of unbalance.
Units and forces of unbalance.
The 4x ISO defined types of unbalance.
Correction methods, single plane, two plane or multi plane balancing.
Rotor types, rigid or flexible.
2. Balancing Machines design
“Soft Bearing Machines”
“Semi-Hard Bearing Machines”
“Hard Bearing Machines”
Calibration Concerns.
3. Rotor Balancing Tolerances
ISO 21940-2003 Balance Trolerances of Rigid Rotors
API Balance Tolerances
USA Miltiary Balance Tolerances.
4. Clearly Define Balancing Requirements.
Define rotor weight and maximum operating speed.
Define correction weight method and position.
Define additions to the rotor such as half keys, pulleys or couplings.
Define tolerance required at support bearings or correction  planes.
5. Request a Written Report.
Summary of work performed on rotor.
Unbalance levels before and after corrections.
Achieved tolerance for each plane compared with standard tolerance.


I first started in the balancing machine business in the early 1970s with IRD Mechanalysis Inc. and to this day I still work with IRD Balancing and another manufacturer from Italy, CEMB S.p.A. who manufacture horizontal and vertical balancing machines. To support the supply of these machines I conduct regular training courses throughout Australia and New Zealand. IRD Mechanalysis Inc. were also one of the pioneers in the measurement of vibration on plant machinery and were the first to introduce hand held data collectors using FFT analysis techniques and Windows based software. After the take-over and demise of IRD Mechanalysis in the mid 1990s we became associated with another dedicated vibration, Swedish, company SPM Instrument AB who made their name developing “Shock Pulse” measurements for the early detection of bearing faults. With this company we have supplied many of their portable analysers and On-Line monitoring systems especially in the water and road/rail tunnel industry. To supply these services I have my own company, Machinery Vibration Specialists Australia Pty. Ltd., which has been in operation since 1979 and is located in Sydney NSW.