Method and system for gram load stabilization by repetitive mechanical back bending of a head suspension assembly

Abstract

A method for stabilizing gram load of a head suspension assembly. The invention includes a mechanical back bending process. After forming, the suspension is subjected to residual stress. During mechanical back bending of the load beam, the applied stress is in the opposite direction of the forming operation. Subsequently, the resultant residual stress around the pre load area is reversed and acted against the pre-existing residual stress remaining from the forming operation. The net effect is a reduction and/or the elimination of residual stress altogether. Depending on the pre-load geometry and desired spring force, the degree of back bending is varied. Typically, a one-time back bending is not sufficient to stabilize the spring region at a microstructure level. It has been demonstrated that such repetitive back bending operation can effectively bring mobile dislocations into equilibrium, and thus reduce or eliminate the hysteresis loop.

What is claimed is:  
     
         1 . A process for manufacturing a disk drive apparatus, the process comprising: 
 providing a load beam in a head suspension assembly, the load beam having a spring region;    forming a pre-load region in the spring region by causing a bend in a first direction in the spring region within the load beam, the bend including a residual stress within a vicinity of the spring region; and    redistributing the residual stress in the spring region by causing a counter bend in a second direction in the spring region, whereupon the first direction is counter to the second direction.    
     
     
         2 . The process of  claim 1  wherein the redistributing is provided by at least one counter bend in the second direction; wherein the forming of the pre-load region mechanically bends the spring region in the first direction.  
     
     
         3 . A method for manufacturing suspension assemblies for hard disk drives, the method comprising: 
 providing a suspension including a pre-load region, the pre-load region including a residual stress within a vicinity of the pre-load region;    determining a degree of back-bending beyond z-height desired to compensate for the residual stress in the pre-load region; and    performing a back bending process on the pre-load region of the suspension to release a portion of the residual stress in the pre-load region.    
     
     
         4 . The method claim in  3  wherein the back bending process is provided more than one time.  
     
     
         5 . A suspension assembly for hard disk drives, the suspension assembly comprising: 
 a suspension member including a pre-load region;    whereupon the pre-load region is free from a residual stress within a vicinity of the pre-load region.    
     
     
         6 . The assembly of  claim 5  wherein the residual stress is caused by manufacturing the pre-load region.  
     
     
         7 . The assembly of  claim 5  wherein the pre-load region comprises a bent region in a first direction.  
     
     
         8 . The assembly of  claim 7  wherein the pre-load comprises a re-bend region, the re-bend region being counter to the bend region.  
     
     
         9 . A process for manufacturing a disk drive apparatus, the process comprising: 
 providing a load beam in a head suspension assembly, the load beam having a spring region;    forming a pre-load region in the spring region by causing a bend in a first direction in the spring region within the load beam, the bend including a residual stress within a vicinity of the spring region; and    redistributing and/or relieving the residual stress in the spring region by causing a counter bend in a second direction in the spring region, whereupon the first direction is counter to the second direction.    
     
     
         10 . The process of  claim 1  wherein the redistributing and/or relieving is provided by at least one counter bend in the second direction; wherein the forming of the pre-load region mechanically bends the spring region in the first direction.