Patent Application
20080041504
Many of the advantages, object and features of the invention will become readily appreciated by reference to the following detailed description when considered in conjunction with the accompanying drawings in which like reference numerals description like parts throughout the figures, and wherein:
The mounting arm 100 can have any shape or geometry that exhibits desirable functional and structural characteristics. For example, the mounting arm 100 can be a mounting arm typically used in hard disk drives with an opening 110 for reducing the rotational inertia of the mounting arm 100. The mounting arm 100 is typically thin, for example, around 0.012 inches.
Referring to
Typically, the oven 210 is heated, at step 300, to an elevated temperature sufficient to soften the mounting arm 100. For example, the temperature of the oven or furnace 210 can be maintained between approximately 600° F. and approximately 1850° F. A thermal controller 220 can be used to set the temperature of the oven 210. To ensure fabrication free from oxidation and contamination, the oven 210 can be oxygen depleted by evacuating the interior 230 to a sub-atmospheric pressure sufficient to cause a vacuum, or by filling the oven interior 230 with an inert gas such as argon or a reducing gas, such as hydrogen.
Once the oven 210 reaches the desired temperature, the mounting arm 100 is inserted, at step 310, for a desirable period. The desirable period is a function of the thickness of the mounting arm 100, the temperature at which the mounting arm 100 is exposed, and the resulting hardness desired in the stainless steel material. In one embodiment, the effect of annealing extends only partially through the mounting arm 100. For example, the desired softness is only in a thin outer surface layer of the mounting arm 100. In another embodiment, the desired softness extends throughout the mounting arm 100. Although the grain structure of the material is softened, stiffness of the mounting arm 100 is maintained. Thus, the mounting arm 100—has less stress at least in the surface layer.
After thermal conditioning, the mounting arm 100 is removed, at step 320, from the oven, and allowed to cool, at step 330, to ambient temperature.
One procedure, referred to as Tape Particle Analysis (TPA), applies an adhesive material, such as an acetate tape, to the surface of the mounting arm 100. The tape adheres to the mounting arm surface and when removed, loose surface particles remain embedded in the tape and can subsequently be counted and analyzed using a Scanning Electron Microscope (SEM).
Another procedure, referred to as Wiped Particle Analysis (WPA), involves wiping a foam cloth material along the surface of the mounting arm 100 to remove any shed surface particles. The material is then analyzed to determine the amount of particle residue collected. A SEM can be used to count and analyze the shed surface particles on the material.
Liquid Particle Count (LPC) can be used. The LPC procedure involves dipping the mounting arm 100 in a fluid, such as deionized water. The immersed mounting arm 100 is subjected to ultrasonic waves that cause shed particles to be released from the surface of the mounting arm 100. The particles suspended in the fluid are counted and binned by sized using a laser sensor.
The repeatability of each procedure is difficult to know as the tests are destructive. However, averaged results examined at different heating temperatures illustrate a relative decrease in surface particle shedding of the mounting arm 100.
Referring to
Test data for WPA and LPC results are depicted in
While certain exemplary embodiments have been described and shown in the accompanying drawings, it is to be understood that such embodiments are merely illustrative of and not restrictive on the broad invention, and that this invention not be limited to the specific constructions and arrangements shown and described, since various other changes, combinations, omissions, modifications and substitutions, in addition to those set forth in the above paragraphs, are possible. Those skilled in the art will appreciate that various adaptations and modifications of the just described preferred embodiment can be configured without departing from the scope and spirit of the invention. Therefore, it is to be understood that, within the scope of the appended claims, the invention may be practiced other than as specifically described herein.
