Single Axis Moment Weight Scales

Product Details

Raptor Scientific’s single-axis moment weight scales are 10x more accurate than knife-edge pivot. They offer blade matching to improve turbine or fan balancing and reduce vibrations. From repairing turbines to manufacturing blades, our MW series of moment weight scales can dramatically reduce your costs through smaller batch sizes and shorter cycle times because of their world-class measurement accuracy and repeatability.

Moment weighing scales measure the moment weight of a blade (see definition of moment weight). These measurements facilitate blade matching to improve turbine or fan balancing and reduce vibrations.

Measuring the moment weight of blades is the first stage of balancing a turbine prior to stacking the rotor.

Typical Applications

Raptor Scientific’s moment weight scales are applicable to both OEM manufacturers and maintenance and repair operations (MRO) providers in a variety of fan or turbine blade industries and applications including:

Jet Engines – Fan and turbine blade manufacturing and turbine assembly
Power Generation – Gas, steam, and wind turbine blade manufacturing and assembly
Helicopters – Blade balancing for manufacturing and assembly
Industrial fans – Fan blade balancing for manufacturing and assembly

Why Measure Moment Weight?

Balance is a major factor in determining the reliability and service life of turbine rotors used in jet engines or power plants. The task of balancing a completed rotor can be greatly simplified if the individual blades are first measured and sorted according to static unbalance moment. They are then assembled in the rotor in matched pairs, resulting in an assembly that is approximately balanced. A better balance can be obtained using our “SPACEBAL” software which compensates for hub unbalance and searches for a best-fit solution involving all the blades, rather than limiting the selection to matched pairs. If the “moment weight” of each blade in an engine is stored in a computer database, then a damaged blade can be replaced with one of identical moment, minimizing the unbalance which results from blade replacement in a repair facility.

Single Axis vs. 3 Axes

When balancing larger blades such as wide chord fan blades, the tangential, axial, and radial moments must be accounted for. To address this challenge, Raptor Scientific has developed the most repeatable and highest accuracy three-axis moment weight scale on the market. This scale provides moment measurements in all three axes. For more information on three-axis moment measurements, please visit our three-axis moment weight scale page.

Key Advantages of Moment Weight Scales
Literature

Accuracy

Higher accuracy moment weight measurements yield individual rotors with small residual imbalances, dramatically reducing the time required for balancing of stacked rotors during final assembly. Raptor Scientific instruments use crossed-web flexure pivots and force restoration technology, resulting in instruments which are at least 10 times more accurate than traditional methods using strain gauges and knife edges.

Range

Higher accuracy means that the same scale can be used for a wider range of blades. Traditional moment weighing scale designs introduce a large percentage error when measuring small blades. The higher accuracy of Raptor Scientific moment weight scale reduces the error by a factor of at least 10, which enables the measurement of much smaller blades with the same instrument that is used to measure larger blades. On the other end of the range, additional range weights expand measurement range up to 1 part in a million.

Repeatability

When used with Raptor Scientific blade adapters, the MW series of moment weight scales ensures that multiple operators will get the same measurement for the same part. This repeatability eliminates the need to run large batches with a single operator, enabling your facility to employ Lean manufacturing techniques by reducing batch sizes and operator cross-training.

Durability

Knife-edge technology dulls over time due to standard wear and tear. This is a known problem in the moment weight machines from other manufacturers, whereas Raptor Scientific employs crossed-web flexure pivots that are not susceptible to damage and wear over time. This results in machines that are more robust and likely to survive under the daily wear and tear of a factory environment.

Temperature Compensation

Some moment weight scales cannot be used on certain days or certain times of day because of the temperature variations in the factory. Our scales use the only temperature-compensated transducers in the industry. This eliminates errors due to temperature changes in an open factory environment.

Radius Compensation

Most moment weight scales require that the blade be fixtured at the exact same radius as the blade has in the engine. By providing the on line computer with blade pan weight information, our scale can correct for deviations from proper blade fixturing radius. This is most useful when measuring blades whose in-engine radius is smaller than the interface radius of the moment weight scale. Raptor Scientific can provide and integrate a force restoration pan weight scale into the system for automatic pan weight data acquisition.

Blade optimization

An optional blade weight optimization software calculates the optimum blade arrangement that minimizes the residual unbalance of the rotor. Unbalance of the hub can be entered to take it into account in the balancing process.

Computerized blade selection (optional)

An on-line computer acquires the moment data and serial number for each blade. After a blade set has been measured, the operator enters the unbalance of the rotor hub on the computer keyboard, and the computer selects the specific blade for each location so that the unbalance of the rotor disc is compensated for by an equal and opposite net unbalance in the blades. If production blades are being measured, then the computer can print a list of matched pairs.

Easy to use

The computer also tells the operator how to run the balancing machine, using a step-by-step procedure which runs on a Windows operating system (supplied). All operations are menu driven with simple instructions. The keyboard is used for operator entries. Reports are automatically generated on the printer and data is stored on the computer hard drive. This data can be accessed through a network. The blade moment is displayed on a digital readout on the computer CRT. If desired, the computer can print a stencil, so the moment can be etched on the blade (optional feature).

Optional tool selection software

A specific adapter is required for each blade to be measured. Relatively unskilled operators can use this system because all necessary information is automatically loaded into the computer when the operator enters the blade part number. The computer chooses the adapter, and activates the specific high and low moment limits for the particular blade chosen.