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Method to Reduce Outer Arm Gram Load Bias in Hard Disk Drives

IP.com Disclosure Number: IPCOM000014674D
Original Publication Date: 2001-Aug-01
Included in the Prior Art Database: 2003-Jun-20
Document File: 1 page(s) / 37K

Publishing Venue

IBM

Abstract

Hard disk drives requiring multiple heads have multiple actuator "arms" which support one or two heads. Outer arms support one head which flys over the top or bottom of the disk stack while inner arms support two heads, one which interfaces with the bottom of the disk above it and another which interfaces with the top of the disk below it.

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Method to Reduce Outer Arm Gram Load Bias in Hard Disk Drives

  Hard disk drives requiring multiple heads have multiple actuator "arms" which support one or two heads. Outer arms support one head which flys over the top or bottom of the disk stack while inner arms support two heads, one which interfaces with the bottom of the disk above it and another which interfaces with the top of the disk below it.

  The gram load (i.e., the force which the actuator assembly exerts on the head in the direction perpendicular to the plane of the disk when the drive is in use) is one factor which determines the flyheight of the head. After assembly outer heads often display lower gram load values than inner heads due to the attachment (swage) process and the fact that there is no opposing force applied by another head on the same arm, which causes the outer arm to bend away from the disk and decrease the gram load of the outer head.

  This invention compensates for the inner versus outer arm gram load difference. It enables populations of head gimbal assemblies with similar gram load properties to retain similar gram load values after integration into the head stack assembly regardless of whether they are attached to inner or outer arms. This reduces the gram load range across all actuator heads which results in greater manufacturing yield and product reliability. The invention also reduces the need for gram load adjust processes, enabling companies to operate more efficient manufactu...