High-Density Recording Characteristics of Obliquely Oriented Particulate Magnetic Tapes by Removal of Disoriented Surface Layer
In order to achieve high recording densities, wide bandwidth and high output, a magnetic tape should have a high Bs, perpendicular orientation, a smooth surface, good head contact, and a small longitudinal component. By using a "LIPS" orienting process which produces media with a longitudinally oriented inside layer and a perpendicular oriented surface layer, we have fabricated obliquely oriented magnetic films based on acicular metal particles; of these, tape oriented at 45° had the widest-bandwidth characteristics. But a significant improvement in output was not obtained because of the existence of disoriented particles in the surface layer, resulting from calendering treatment. We tried to remove this surface layer using polishing sheets. An obliquely oriented (45°) tape exhibited an improvement in short-wavelength output (by 10 dB at 0.3 ¿m) after the thickness of the disoriented layer was reduced by 0.12 ¿m.
Analysis due to vector magnetic field for recording characteristic of metal evaporated tape
Metal-evaporated tape (ME tape) is one of the most promising materials for high-density magnetic recording. In a previous study, we reported that the recording characteristics of ME tape are directly affected by the columnar microstructure of the magnetic layer (Co-Ni-O magnetic film). In this study, we have conducted the theoretical analysis of the effects of both head motion and the vector magnetic field H θ , which is essentially parallel to the columnar longitudinal axis. The results of this analysis offer an effective explanation of the recording characteristics of ME tape.
Traceability strategy for gear-pitch-measuring instruments: development and calibration of a multiball artifact
There is a strong demand to ensure the traceability of gear-measuring instruments (GMIs). We propose a multiball artifact (MBA) for the evaluation of pitch-measuring accuracy. The aim of the MBA is to transfer the minimum uncertainty from a calibrated value at the National Metrology Institute of Japan (NMIJ) to a measured value of GMIs at a shop floor. The MBA is composed of equally spaced high-accuracy balls around an axis. The pitch-measuring accuracy of GMIs is evaluated by measuring the angular pitch deviation of the balls instead of the angular pitch deviation of a gear. We calibrated the angular pitch deviation using a coordinate measuring instrument (CMM) at the NMIJ and adapting a multiple-orientation technique. We proposed a calibration strategy of the angular pitch deviation. The calibration value of the pitch deviation for the MBA at the NMIJ was obtained with a measurement uncertainty (U95) of 0.2 µm. We evaluated the pitch-measuring accuracy of a GMI using the calibrated MBA. Each value of U95 for the cumulative and single pitch deviations for the left and right flanks was less than or equal to 0.5 µm. The small uncertainty was transferred from the NMIJ to the GMI.