Original Date: 07/13/1992
Revision Date: 01/18/2007
Best Practice : Gun Tube Inspection Station
During the late 1980s, the 120mm tank cannon produced by Watervliet Arsenal (WVA) experienced a significant number of chrome plate adhesion failures during proofing. This problem prompted WVA to institute fundamental changes in gun tube inspection and manufacturing process controls.
Army policy and the gun manufacturing industry are moving away from the conventional hard gaging and manpower intensive inspection operations. In particular, the traditional manual final inspections have been replaced with statistical process control, continuous process improvements, and coordinate measurement machines. (As a result, less but more complex instrumentation with variable and functional gages have been designed.) These innovative quality tools and techniques have improved manufacturing operations, and reduced costs such as inspection and rework, thereby improving product quality and reliability beyond the traditional or manual inspection means.
WVA designed and built an automated Gun Tube Inspection Station (GTIS) using the central computer controller and commercial electronic gaging systems. The computer -- a stand-alone Hewlett-Packard Series 200 computer modified to accommodate inspection of the various gun tube designs -- directs and controls the drive mechanism (motor controller) and inspection head. The inspection head is passed through the length of the bore to measure straightness, concentricity, and plate thickness down the length of the bore. This improved accuracy, which is permanently recorded, is directly related to the interpretation of electronic signal measurements. The operator can make highly accurate estimates of analog readings but is not able to duplicate the accuracy or repeatability of an analog-to-digital interface attached to a computer.
Since inception of the GTIS, errors associated with chrome plate thickness, bore diameter and bore straightness have been reduced more than 50%, thereby increasing efficiency and accuracy of data for gun tube manufacturing operations while reducing costs.
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