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Technology Stocks : Disk Drive Sector Discussion Forum -- Ignore unavailable to you. Want to Upgrade?

To: T Bowl who wrote (3624)	6/11/1998 9:26:00 AM
From: Stitch	Respond to of 9256

Tbowl, Burnish occurs in several steps (including one called "kiss" burnish prior to the final lubrication of the finished disk. The final final burnish actually occurs as a first step when the disk is certified and glide tested(final test). The burnish mechanism is integrated into the same spin stand that performs the glide test and the certifying. The test bed is based on a heavy piece of granite with either a single air bearing spindle or dual spindles. Burnish is performed with a special head (called a waffle head) that is passed (flown) over the disk at ultra low flying heights. It is designed to knock off asperities and debris. Then another actuator introduces the glide test head, also a specially designed test head, which has an acoustically coupled transducer mounted on it with a flex circuit to logic that will amplify any perturbation to the head. (If there is an asperity the head will momentarily flutter, or actually strike the asperity causing a change in resistance through the transducer.) In this event it is recorded as a glide error. A single glider error during this test and the disk is rejected. Then a third actuator flies a standard read-rite (MR) head over the disk. A specified test pattern is written on the disk at very high density and then read back by the read element on the head. Special circuitry looks for a read back signal that is either too low (called a missing pulse) or too high (called an extra pulse)compared to the expected signal based on the initial amplitude of the write function. This is a form of testing for signal peak shift. All this on one system! What a bargain at $ 135,000 huh? (That does not include the automation equipment that trundles the disk to the certfier then sorts the results). The market leader for this equipment in the U.S. is a company called Phase Metrics. The leader in Japan is Hitachi-Deco. Phase Metrics recently had a bond offering. If you are interested I can send it to you. So far they have not had an IPO and are still a privately funded (venture capital) company. Best, Stitch