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Portable Head-Tape Interface Accelerated Wear Apparatus

IP.com Disclosure Number: IPCOM000042000D
Original Publication Date: 1984-Mar-01
Included in the Prior Art Database: 2005-Feb-03
Document File: 3 page(s) / 35K

Publishing Venue

IBM

Related People

Bhushan, B: AUTHOR [+2]

Abstract

There has been a need to develop accelerated wear tests so that wear rates of tape-drive products over their lives (on the order of 10 years) can be predicted by running the laboratory tests for short periods (on the order of a few days). Also, there is a need to have versatile testers which can be used to study parameter dependence of, e.g., tension, speed, acceleration, wrap angle, different head contours, temperature, humidity, and particle contamination. Friction measurements would also be useful. A study of the wear mechanism can be efficiently conducted if the test apparatus is capable of running under variable conditions and is easily accessible. Accordingly, an accelerated wear tester was provided, as illustrated in Fig. 1. As shown, two spools are used to wind and unwind the tapes.

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Portable Head-Tape Interface Accelerated Wear Apparatus

There has been a need to develop accelerated wear tests so that wear rates of tape-drive products over their lives (on the order of 10 years) can be predicted by running the laboratory tests for short periods (on the order of a few days). Also, there is a need to have versatile testers which can be used to study parameter dependence of, e.g., tension, speed, acceleration, wrap angle, different head contours, temperature, humidity, and particle contamination. Friction measurements would also be useful. A study of the wear mechanism can be efficiently conducted if the test apparatus is capable of running under variable conditions and is easily accessible. Accordingly, an accelerated wear tester was provided, as illustrated in Fig. 1. As shown, two spools are used to wind and unwind the tapes. These are driven by variable speed motors to get desired acceleration rates and sliding speeds. An endless loop can also be used, if desired. The tape from one spool goes over a frictionless pulley to a vacuum column, then over an air bearing to a head assembly (containing two air bearings on either side) and over a frictionless pulley to another spool. A head is mounted independently of the neighboring air bearings. Therefore, any head size or shape can be used. Head surface can be brought in contact on either side of the tape, which is desirable for optical flying height study or interface temperature measurement study and because different tape drives have different head designs. The wrap angle can also be varied. A thermoelectric cooler can be mounted next to the head to vary the head temperature. A vacuum column is used in order to have complete flexibility to vary tension. The need for a capstan motor and two vacuum columns used in most current drives is eliminated which provides simplicity and compactness. The tester is small. Therefore, it can be placed in a humidity chamber for environmental tests. An accelerated head design was developed in a "bump" head (Fig. 2). The bump head provides higher contact stress for accelerated wear. This design eliminates the variation of flying height due to tension and speed, and provides the radius of curvature for any head to be tested to avoid tape stiffness effects. The center of the bump consists of a magnetoresistive (MR) element which is used to measure the wear of the head. The resistance changes as a result of MR element wear. Two pressure transducers to measure bearing pressure are installed in the air bearings on both sides of the head. This gives the coefficient of fr...