A Practical Approach to Field Precision Dynamic Balancing

Leading Machinery Improvement

Course Objective:

This course will provide practical understanding as well as techniques for dynamic balancing of the various types of industrial rotors in-place in the plant. Special emphasis will be given to enable very close precision balancing of all rotors, including those that are narrow and overhung.


  • Three days

Who Should Attend

This course is excellent for those in vibration, maintenance, service and engineering teams responsible for smoothest running machines.

Many balancing training programs start with how to operate the balancing machine itself. Understanding mechanical and electronic setup is certainly necessary, especially for the balancing machine operator. However, such details are not necessary for vibration and machinery reliability specialists. Therefore, this course will not deal with the balancing machine itself. Instead, it will focus on how to get all machines to be truly reliable by obtaining considerably closer precision balancing on all types of machine rotors.

Understand The Underlying Principles

Update first concentrates on the basic principles of what is occurring while balancing. For example, unbalance and counterbalance forces are based on vectorial combinations of forces, rather than ordinary arithmetic. When taught in simple, easy-to understand, practical language, the operator soon understands what causes difficulties in shifting angles, non-proportional readouts, etc. With practical exercises, the operator will become proficient in understanding the problems, and will be able to prevent the problems from occurring in the first place.

Prevent Rotor Types Difficulties

There are special difficulties that occur with certain rotor types such as: balancing an ordinary motor armature or simple roll; balancing overhung (cantilevered) rotors; and balancing rotors that are relatively narrow (such as narrow pump impellers). These special balancing difficulties may cause the operator to give up and balance such rotors in only a single plane.

Prevent Tooling Difficulties

Resistance to precision balancing is often due to tooling problems such as balancing shafts, arbors and mandrels. When balancing to precision levels, every tooling and rotor assembly-related error becomes more pronounced and can counteract the precision put into balancing. This course eliminates these problems through practical, easy-to-implement precautions and procedures. This involves such items as: difficulties due to improper key lengths, eccentricities, certain types of slip fits, non-square ends, arbor diameters that are nearly equal to balancing machine bearing diameters. Tooling and assembly-related errors and difficulties have little impact when a company balances to mediocre levels. Update understands the techniques to eliminate these assembly-related and tooling errors to produce a truly precision balanced assembly.

Techniques with Trial Weights

Some balancing requires trial weights. Conversion to final corrections (such as welded weights, drill holes, or grinding) could cause all trial weight balances to deteriorate. Learn practical techniques normally learned after many years of experience.

Proper Assembly for Precision Balance

The best precision-balanced rotors could lose most of their precision due to just a few misunderstandings in final rotor assembly. How to maintain precision with relatively loose slip fits is very easy, but does require practical, easy-to-implement techniques, not only at the balancing machine, but on the part of those who assemble the final product. Determining proper key lengths, demonstrating the effects on rotor positioning due to burrs, dings, sharp corners, etc., sounds simple in the classroom, but changing old habits is difficult.

Coordinate Precision Balancing with Others

The course also concentrates on how to deal with changing philosophies and techniques from the old (mediocre) to the new (precision). This involves coordination and cooperation between those who do the balancing, those who assemble, and those who supervise to make it all happen. This also involves machinery suppliers, vendors and contractors.

Other Topics

The most precise balancing in the shortest time requires many other individual practical tips. Experience coupled with attention to detail in using these techniques enable the participants to quickly learn what could otherwise be learned only by experience measured in years.

Course Content

Overview of Unbalance Forces

  • Understanding the various unbalance forces and how they affect each other
  • Understanding various forms of dynamic unbalance; single plane unbalance, static unbalance, couple unbalance
  • Effects of counterbalance force in various relationships to the real unbalance (when at the proper position; slightly off-angle; larger off-angle; how to keep under control).

Practical Techniques

  • Ordinary two-plane rotor balancing
  • Alternative methods for special two-plane balancing of narrow and overhung rotors
  • Tolerance evaluation (including narrow and overhung rotors).
  • Dealing with the difficulties provided by balancing tooling; balancing arbors; expansion mandrels; defective or non-precision tooling (such as non-square or dented shaft ends).
  • Determining weight issues; adding, removing, splitting and combining weights to achieve a closer precision balance in the shortest time.
  • Various means to obtain phase readings for field balancing

Other Practical Considerations

  • Phase reading techniques for field balancing
  • Determining true precision balance tolerances
  • Understanding low speed balancing on shop balance versus high rotor operating speed balancing
  • Determining and compensating for wide angle corrections
  • Determining balance tolerances based on the various rotor type requirements: International standards, precision standards, and intermediate standards (for difficult situations)

Compensating for and Preventing Problems

  • Errors due to size differences between available tooling and the rotor’s actual shaft
  • Errors due to relationship between shaft diameter and turning bearings
  • Errors caused by improper setup
  • Rotor assembly errors

Working with People who Affect the Final Product

  • Contractors
  • Machinery Manufacturers
  • Outside and Inside Shops
  • Supervisors unfamiliar with precision standards