Guides for engineers
Practical material for engineers specifying, buying or running balancing equipment. Everything here is free and nothing asks for your email address.
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Three questions decide it.
If you are at the beginning of this, three questions narrow it down quickly.
If it has its own journals, it belongs on a horizontal machine. A disc with a central bore belongs on a vertical machine.
A narrow disc usually needs one plane: static balancing. A wider or longer rotor needs two: dynamic balancing. The faster it turns, the sooner two planes are needed.
Series production of one part favors automatic machines with dedicated tooling. Varied work favors a flexible machine that changes over quickly.
Choosing a machine
Decided by the part.
Choosing a machine
The names describe which way the rotor's axis points on the machine; the choice follows from one question: does the part have its own shaft?
Read the articleChoosing a machine
A balancing machine is chosen from the rotor outward: seven facts about your parts decide the machine.
Read the articleBalancing basics
Static balancing corrects a rotor in one plane and suits thin, disc-shaped parts; dynamic balancing corrects in two planes for longer rotors.
Read the articleStandards & testing
The numbers behind balancing.
Balance tolerances for rigid rotors are set out in ISO 21940-11, which replaced ISO 1940-1. Machine testing is covered by ISO 21940-21.
Standards
A balance quality grade, written G followed by a number, sets how much residual unbalance a rotor is allowed.
Read the articleStandards
A balancing machine is verified against ISO 21940-21, using a proving rotor and known test masses.
Read the articleStandards
Two figures describe how good a balancing machine is: Umar, the minimum achievable residual unbalance, and URR, the unbalance reduction ratio.
Read the articleApplications
Part by part.
Applications
A driveshaft is balanced dynamically, as a complete assembly, spinning at or near the speed it runs at in the vehicle.
Read the articleApplications
An EV traction motor rotor is balanced in two planes on an automatic machine, to a much tighter tolerance than an industrial motor.
Read the articleApplications
A narrow impeller is balanced in one plane and a wide one, or a multistage rotor, in two.
Read the articleStraightening
An automatic straightening machine measures runout along the part, presses it slightly past straight so it springs back true, then measures again.
Read the articleTools
Tools you can use now.
Calculator · ISO 21940-11
Enter rotor mass, service speed and balance quality grade. Returns the permissible residual unbalance and the split across two correction planes, with every step of the working shown.
Open the calculatorTool
Enter your rotor and see the best-fit machine.
Open the machine finderTool
Enter turbine or fan blade moment weights and get a slot-by-slot fitting order with the lowest residual unbalance.
Open blade patterningAsk us directly
Send us the component. A drawing, the weight, the running speed and the tolerance you are working to are enough for us to tell you what suits it, and to say so plainly if you do not need a new machine at all.
