Effect of Flattening Cracked Medium on Positioning Accuracy of a Linear Magnetic Encoder

Abstract

Linear magnetic recording medium is a crucial and necessary component in a linear magnetic position sensing system. During the manufacturing of the magnetic medium, shape defects would often be observed due to various manufacturing processes. As a result, shape defects in the magnetic medium would alter the recording accuracy during position measurement of the magnetic reader. Thus, a flattening process is introduced for flattening of curved magnetic medium. Previous studies have demonstrated its effectiveness in flattening of magnetic medium. In this article, a further step is taken to examine the crack formation in the microstructure of the magnetic medium during flattening process to ensure the quality and recording accuracy of the magnetic medium. The experimental results have demonstrated that crack propagation would continue to grow under the influence of flattening process if crack initiation is found prior to the flattening process. Nonetheless, the measured linear position accuracy showed that the accuracy improved after the flattening process despite crack propagation occurring on the mechanical quality of the medium. In other words, the results have demonstrated that the effect of mechanical shape defects on linear position accuracy is more important than that of crack formation on the magnetic medium. Through understanding the crack formation of the magnetic medium, the accuracy of the recording medium can be improved by modification of the magnetic medium and flattening conditions.