Superior accuracy – Conventional moment weight scales use strain gage load cells to measure moment. We use force restoration technology. A laser senses the deflection of the moment arms and electromagnetic actuators apply an equal and opposite force to each moment arm to restore the scale to its original position before the blade was inserted in the adapter. This eliminates mechanical non-linearity and results in a signal to noise ratio which is 1000 times better than a strain gage load cell.
Repeatable, no wear pivots – Conventional moment weight scales use a pair of knife edges which are oriented at right angles. Knife edges wear over time and the scale becomes less repeatable and less accurate. We use a spherical gas bearing which floats the moment arm on a thin film of air as the pivot of our MW40KF and crossed web flexures in our MW904F. Neither technology presents any risk of wear. Our pivots retain their full accuracy for 30 years or more, and require no maintenance.
No hydraulics – No leaks, no high pressure lines and associated risks.
Low Maintenance – There are no consumable components in our scales. Conventional scales use knife edges which wear and hydraulic lines which need to be checked for leaks and refilled. Our scales need very low rate of maintenance and less frequent calibration.
Precision Blade Adapters – Space Electronics manufactures the most repeatable blade adapters that hold the blade exactly in the right position. These adapters enable our customers to make full use of the extreme accuracy of our scales.
Why Our Multi-Axis Moment Weight Scale Is Unique
Central pivot uses spherical air bearing
Conventional moment weight scales use a pair of knife edges which are oriented at right angles. We use a spherical gas bearing which floats the moment arm on a thin film of air. This frictionless pivot has a center of rotation which only varies a few millionths of an inch, even if the scale is severely overloaded while the blade is being inserted in the adapter. There is no wear in this pivot. It retains its full accuracy for 30 years or more, and requires no maintenance.
Force restoration technology
Conventional moment weight scales use strain gage load cells to measure moment. We use force restoration technology. A laser senses the deflection of the moment arms and electromagnetic actuators apply an equal and opposite force to each moment arm to restore the scale to its original position before the blade was inserted in the adapter. This eliminates mechanical non-linearity and results in a signal to noise ratio which is 1000 times better than a strain gage load cell. The error in comparing blades to a master blade is 0.0003% of full scale.
No sliding range weights
Unlike conventional moment weight scales, it is not necessary to add weights to a hanger or slide weights along a shaft in order to measure the range of moments from 0 to 30,000 oz-inch. A binary range weight system within the scale automatically lowers the correct weight on the moment beam, resulting in greatly increased dynamic range. It is not necessary to counterbalance the adapter before making a measurement. The scale first measures the moment due to the adapter, and then measures the moment with the blade installed.
Automatic blade rotation
It is not necessary for the operator to rotate the blade 90 degrees in order to measure the 3rd axis of the blade. This is accomplished automatically by the scale.
Many blades can be measured with the same adapter
It is not necessary to use a separate adapter for different blades. As long as the root dimensions are the same, then a single adapter is usually sufficient. An optional pan weight scale can be supplied which measures blade weight with an accuracy of better than 0.0001% of full scale. The on-line computer then converts the measured moment to the value at the correct Z-plane radius. This results in a major saving in system cost and eliminates the need for the operator to repeatedly change adapters.
Blades are loaded vertically
On conventional moment weight scales, the blade is loaded horizontally in the adapter and hangs down below the machine centerline. When the clamping mechanism is actuated, the blade rocks upward, altering the position of the blade root. On our scale, a hinged adapter allows the blade to be inserted while it is in a vertical position. The blade then hangs straight down, allowing gravity to press the blade root against the adapter. When the blade is clamped, it retains its correct position.
Blade is clamped automatically
The adapter clamp is actuated by air, rather than using hydraulic cylinders. The air is supplied to the clamp through a flexible coupling inside the machine. There is no need to attach a hydraulic hose to the adapter, and there is no oil within the adapter. This eliminates the mass shift error which occurs with hydraulic systems when the blade is rotated from a vertical to a horizontal position.