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UAI gages automatically and continuously measure and recalibrate themselves based on a patented principal of double reference technology. This method removes all environmental effects from the measurement. In an on line measurement application the sensors have to be permanently mounted to some form of fixturing, to automatically measure product as it is transferred through the gages. This fixturing needs to be robust to prevent any movement of the sensors so that accurate measurements can be made. UAI offers a variety of robust standard fixturing ("O", "C" and scanning frames) to suit specific industries and applications. Depending upon the material used to construct the fixturing, there will be fixture movement. The amount of movement of the fixture depends upon the coefficient of expansion/contraction of the material used and the temperature extremes in the plant. If the fixturing is made out of steel and the plant temperature varies from 50° F in the cold part of the night to 100° F during the hot part of the day, the fixture will expand by about 0.010 inches. Without correction the measurement of the gage would have a 0.010 inch error. UAI's patented AutoZ-Cal completely removes this error. Figure 7.1 to the right illustrates the AutoZ-Cal feature:
When the thickness system is initially set up, the separation between the opposing sensors determines the target thickness. If the sensors move closer together because of fixture thermal expansion/contraction, the measurement will be in error. If the fixture movement were 0.010", the measurement would be off by 0.010" . If there were a product pileup or collision or some accident that caused the fixture to move by 0.050", the measurement would contain a 0.050" error. The AutoZ-Cal feature eliminates this error by continually measuring the separation between the two sensors and applying a correction for fixture movement.
