What Do Soft Bearing Balancing Machines and Hard Bearing Balancing Machines Mean?

Dynamic balancing machines are basically divided into two main categories based on their bearing systems: soft-bearing and hard-bearing machines. This classification determines how the machine measures unbalance and which types of applications it is best suited for. Soft-bearing balancing machines have a flexible structure at the support points where the rotor is mounted. This flexibility allows them to measure the amplitude of vibrations caused by unbalance. These types of machines generally operate with high precision at lower speeds and are particularly ideal for delicate rotors. While soft-bearing machines can be more complex to install and calibrate, they offer exceptional accuracy in certain frequency ranges.

On the other hand, hard-bearing balancing machines use a rigid, or rather inflexible, structure at the support points where the rotor is mounted. These machines work by measuring the force created by unbalance on the bearings. Their strong and durable construction makes them preferred in industrial environments. Hard-bearing machines can accommodate a wider range of rotor weights and sizes and can be quickly adjusted for different rotors without requiring calibration. This makes them extremely efficient in mass production and when balancing various parts. At MBS Balance, we offer both soft- and hard-bearing solutions tailored to our customers' needs and guarantee the highest performance using the latest versions of both technologies. The type of machine that's right for you depends on the characteristics of the parts you'll be balancing and your production requirements.

The physical principle that determines the difference between the two systems is the position of the operating region relative to resonance. Soft-bearing machines operate above the suspension resonance and measure the displacement (amplitude) proportional to the unbalance; therefore they require calibration with a trial weight for each new rotor. Hard-bearing machines, on the other hand, operate below resonance and measure the force acting on the bearings with force transducers; once the part dimensions (plane positions, radii, journal distance) are entered, no trial weight is needed thanks to the permanent calibration.

This distinction directly determines practical efficiency: in workshops where a wide variety of parts are balanced, the hard-bearing machine is much faster because no trial run is made per setup, and it delivers results in a single pass with low cross-effect. Soft-bearing systems, on the other hand, can offer superior resolution at very low residual unbalances on a specific part. MBS Balance works with you to determine which of the two technologies best establishes the balance of overall efficiency and precision for your production profile.