Used Balancing Machines for Sale — 153

Balancing Machines

Each rotating body has got an unbalance. Because in practice its mass axis (containing the centre of gravity) never coincides with the rotational axis. There are many reasons for the size of that unbalance, for example the procedures used for machining or assembly. When a rotating body is revolving in its bearings the unbalances cause dynamic forces and noise. Hazards for persons, machines and the environment may occur. Therefore balancing is a must for modern machines running at high speeds and requiring high precision. Balancing process means to reduce the amount of unbalance. For balancing it is checked whether the mass axis of a rotor is displaced from its rotational axis and how distant that is. If necessary – the mass distribution of a rotating body is being changed by balancing. As a result the forces and vibrations caused by the unbalance stay within permissible limits. In order to establish and maintain proper tension in a machine, a mechanic often needs the help of a specialized tool. A balancing machine, or balance machine, is used to help create this type of symmetry within rotating machines. It can perform this task through individual part rotation and sensor detection. 

The balancing machine and its principle

In a typical balancing machine for sale, a set of two firm pedestals are accompanied by bearings and a suspension. Most machines have the capability to balance a variety of parts. These parts can include rotors for electric motors, disc drives, turbines, disc brakes, fans, pumps, and propellers. To use a balancing machine, the item requiring alignment may be placed directly onto the bearings, either manually or mechanically. The unit is then rotated, using an air-, end-, or belt-drive. During the rotation, the item will vibrate. This vibration will enable the attached sensors within the machine to determine how unbalanced the unit may be, and therefore how much shift is needed to establish equilibrium. It can also pinpoint where weights are needed, if any, for balancing, and where the weights should be placed. 

Uses of Balancing Machines 

Balancing machines are used to:

• To minimize vibrations, noise etc. which in turn improves the machine life and reduces operator fatigue
• To minimize the dynamic stressing and fatigue, which leads to reduce sizes of machine elements & foundations necessary
• To reduce power losses, as vibrating systems absorb energy due to the damping factor present in the system
• To avoid inaccuracy & improper functioning of adjacent machinery due to transmission of vibrations

Classification of Balancing Machines 

There are two main types of balancing machines based on the measurement principle which differ in their suspensions and not in the bearings:

Soft-bearing balancing machine 

A soft-bearing balancing machine does balancing at a higher speed than the resonance frequency. A soft-bearing machine is thus near from a high-speed balancing machine. Soft-balancing machines are better for high-volume production, as they need to be calibrated for each different part being balanced. 

Hard-bearing balancing machine 

In a hard-bearing machine, balancing is done at a frequency lower than the resonance frequency of the suspension. A hard-bearing machine is generally more versatile and can handle pieces with greatly varying weights, because hard-bearing machines are measuring centrifugal effects and require only a one-time calibration. There are three main types of balance machines based on their application: 

 
• Horizontal balancing machines
• Vertical balancing machines
• Universal or special balancing machines

Horizontal axis balancing machine 

These types of machines are mainly used for two plane (Dynamic) balancing. Single plane (Static) balancing is also possible. The rotor runs with its axis of spin in a horizontal plane. 

Vertical axis balancing machine 

These types of machines are mainly used for two plane (Dynamic) balancing. Single plane (Static) balancing is also possible. The rotor runs with its axis of spin in a vertical plane. 

Universal or special balancing machine 

The universal balancing machine is named for the wide variety of parts it can balance. It is also known as a cradle balancing machine because of the way the part is supported on the machine. This model of balancing machine can be used for both single and two plane rotor balancing. With the proper tooling and correction modes this "universal" balancer can be configured to accommodate a variety of rotors up to 20,000 lbs. There are three main types of balancing machines based on the type of unit that needs to be balanced:

•  Static balancing machines 
•  Blade balancing machines 
• Portable balancing machines

Static balancing machine Static balancing machines can test the balance of a unit without spinning. The unit is placed vertically in the centre of what looks like a scale and the pressure from the various areas of the scale measures the imbalances of the unit. This method limits the machine to measuring only one plane of the unit, but the advantages of using this kind of machine are price and speed.  Blade balancing machine Blade balancing machines endeavour to make sure parts are balanced during assembly. Fans, turbines and propellers are all good examples of common units that use this machine. For example, before a fan is assembled the blades are all weighed and a piece of software matches the blades together so as to eliminate as much imbalance as possible. Portable balancing machine Portable balancing machines are perfect for measuring the imbalances in machines whose parts cannot be disassembled. These tools come with displacement sensors and a photocell which are connected to the machine being measured. The portable balancing machine senses the vibrations of the spinning unit and calculates any adjustments that need to be made. 

Applications of Balancing Machines

The following are some of the applications of balancing machines 

•  Armature Balancing 
•  Combine Rotor Balancing 
•  Crankshaft & Engine Balancing 
•  Cutter Wheel Balancing 
•  Rotor Balancing 
•  Super Charger Balancing 
•  Clutch Balancing 
•  Coupling Balancing 
•  Flexplate Balancing 
•  Flywheel Balancing

Popular Manufacturers

Some of the well-known manufacturers of balancing machines are: AMERICAN HOFMANNORATION, ITW Balance Engineering, LINGLING, KAISER SISTEMAS De EQUILIBRADO, HINES INDUSTRIES, IRD Balancing,  DIAMECH 2000 Ltd., SCHENCK RoTec GmbH, CIMAT, SCHMITT EUROPE and ROLLOMATIC.