Recessed Trailing Air Flow Dams for Disk Drive Head Stability
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Solution Overview
Problem
Magnetic hard disk drives face challenges in maintaining optimal flying height and reducing debris accumulation on the air bearing surface, which affects tribological performance, leading to reliability and lifetime issues.
Innovation Solution
The design incorporates a slider with an air bearing surface featuring trailing pads, recessed air flow dams, and sub-ambient pressure cavities to manage pressure and airflow, reducing debris accumulation and enhancing flying height stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the flying height is reduced to increase data storage density, then the real density of data stored on the disk surface increases, but the tribological performance degrades leading to unacceptable lifetime and reliability
Solution Approach 1:
The air bearing surface is divided into multiple zones with different geometries and functions: leading edge pads for pressurization, trailing edge dams for flow control, and side walls for lateral confinement. Each zone has optimized local characteristics that collectively maintain stable flying height and reduce wear, enabling low flying heights without sacrificing reliability.
Solution Approach 2:
The air bearing surface is segmented into distinct functional regions including leading edge pads, trailing edge dams, and side walls. This segmentation allows independent optimization of each region's geometry to control air flow patterns, maintain pressure distribution, and stabilize flying height at reduced clearances.
2Manufacturing precision
If the flying height is reduced to increase data storage density, then the real density of data stored on the disk surface increases, but friction and wear between the slider and disk surface increase
Solution Approach 1:
The invention uses a precisely engineered air bearing surface that generates hydrodynamic air pressure to levitate the slider above the disk surface. The air flow dams and side walls control air flow patterns to maintain stable pressure distribution, creating a non-contact bearing that eliminates solid friction and wear while enabling reduced flying heights for higher storage density.
3Reliability
If lubricant and debris accumulate on the air bearing surface, then the flying characteristics of the slider change, but this leads to reading or writing errors and head crash
Solution Approach 1:
The trailing edge air flow dams are designed to extract and redirect air flow away from the trailing edge region where debris accumulation is most problematic. By controlling the air flow paths through these dams, the design prevents lubricant and debris from accumulating on critical air bearing surfaces, maintaining stable flying characteristics and preventing head crashes.
4Reliability
If the air bearing design is optimized to reduce debris accumulation, then tribological performance improves, but the design complexity increases
Solution Approach 1:
The air bearing surface incorporates localized geometric features such as trailing edge dams with specific recess depths (0.05-0.5 microns) and side walls positioned at precise locations. These local modifications to the air bearing geometry control air flow patterns to prevent debris accumulation and maintain tribological performance, achieving improved reliability through targeted local optimizations rather than overall design complexity.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This design effectively reduces debris accumulation and maintains optimal flying height, improving the tribological performance and reliability of the disk drive by creating controlled pressure regions and airflow patterns.
Implementation Method 1
The magnetic transducer is typically supported in very close proximity to the magnetic disk by a hydrodynamic air bearing. As the motor rotates the magnetic disk, the hydrodynamic air bearing is formed between an air bearing surface of the slider of the head, and a surface of the magnetic disk.
Implementation Method 2
Each of the left and right trailing air flow dams is recessed from the primary plane by a step depth in the range 0.05 to 0.5 microns, and the sub-ambient pressure cavity is recessed from the primary plane by a cavity depth in the range 0.8 to 2 microns.
Data Source
AI summary
A head has a slider with an air bearing surface having a left trailing air flow dam extending from a trailing pad along a lateral axis, and a right trailing air flow dam extending from the trailing pad along the lateral axis in an opposing direction. A sub-ambient pressure cavity is disposed adjacent to and upstream of at least one of the trailing air flow dams. The trailing pad and the left and right trailing air flow dams together laterally span at least 75% of the width of the slider. Each of the left and right trailing air flow dams is recessed from the primary plane by a step depth in the range 0.05 to 0.5 microns, and the sub-ambient pressure cavity is recessed from the primary plane by a cavity depth in the range 0.8 to 2 microns.