A sensitive radiotracer technique for measuring abrasivity of magnetic recording tapes

Abstract

A special magnetic tape transport system and radioactive dummy recorder heads were designed and constructed to provide a sensitive, rapid, and precise method of measuring the abrasivity of magnetic recording tapes under conditions closely approximating their use in actual instrumentation recorders. The tape contact face of the dummy-recorder head was made of neutron-activated Kovar. Two-hundred-foot samples of 0·5-in. wide instrumentation tape were tested using the same tape wrap angles, tensions, and speeds as those used in actual recorders. The amount of radioactivity transferred to the tape was used to establish the amount of Kovar worn from the head. The precision of 5-pass tests was about 4%. Virtually all of the abraded radioactive material adhered to the tape. Abrasivity was directly proportional to tape tension, but independent of tape speed. Relatively large differences in abrasivity were found, even among samples from the same reel of tape. Comparison of measurements made with radioactive heads of two different designs indicates that the test method gives relative abrasivity values applicable to actual recorder heads.