Abstract:
A slider that minimizes lubricant accumulation includes bearing surfaces that provide above ambient fluid pressure, a cavity located between two bearing surfaces and at least one step feature that is spaced apart from the bearing surfaces and is located in and protrudes from a floor of the cavity at a height that is less than a height of the bearing surfaces. The at least one step feature includes surfaces configured to diverge and converge airflow in the cavity.

Description:
BACKGROUND 
       [0001]    Lubricant acts as a protective coating on the surface of data storage media to prevent corrosion to its magnetic layers. During data storage device operation, a slider, having transducer elements, flies over the data storage medium and interacts with the coating of lubricant on the surface. One common effect of the interaction between the slider and the lubricant includes mechanical lube pickup due to the lubricant ripping off the storage medium under high air-shear at the trailing edge of the slider. 
         [0002]    The discussion above is merely provided for general background information and is not intended to be used as an aid in determining the scope of the claimed subject matter. 
       SUMMARY 
       [0003]    A slider is provided that minimizes lubricant accumulation. The slider includes a slider body having an outer side edge, an inner side edge, a trailing edge, a leading edge, an outer rail positioned adjacent to the outer side edge of the slider body, an inner rail positioned adjacent to the inner side edge of the slider body and a center rail positioned between and spaced apart from the outer rail and the inner rail. The slider further includes first and second nozzle features each having a divergent portion and a convergent portion. The first nozzle feature is positioned between and separated from the outer rail and the center rail. The second nozzle feature is positioned between and separated from the inner rail and the center rail. Each nozzle feature is located a spaced distance from the trailing edge and the convergent portions are located in closer proximity to the trailing edge than the divergent portions. 
         [0004]    A method of minimizing lubricant accumulation on the slider includes preventing fluid stagnation zones from occurring near a trailing edge of the slider body by locating the first nozzle feature on the cavity surface of the first cavity and locating the second nozzle feature on the cavity surface of the second cavity. 
         [0005]    This Summary is provided to introduce a selection of concepts in a simplified form and are further described below in the Detailed Description. This Summary is not intended to identify key features or essential features of the claimed subject matter, nor is it intended to be used as an aid in determining the scope of the claimed subject matter. The claimed subject matter is not limited to implementations that solve any or all disadvantages noted in the background. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0006]      FIG. 1  illustrates a perspective view of exemplary components of a data storage device including a head stack assembly and a data storage medium. 
           [0007]      FIG. 2  illustrates an enlarged bottom plan view of a slider according to one embodiment. 
           [0008]      FIG. 3  illustrates an enlarged bottom perspective view of the slider illustrated in  FIG. 2 . 
           [0009]      FIG. 4  is an enlarged perspective view of one of the nozzle features illustrated in  FIGS. 2 and 3 . 
           [0010]      FIG. 5  is a bottom plan view of the slider illustrated in  FIG. 2  including streamlines of airflow. 
           [0011]      FIG. 6  illustrates a bottom plan view of a slider according to another embodiment. 
           [0012]      FIG. 7  illustrates a bottom perspective view of the slider illustrated in  FIG. 6 . 
           [0013]      FIG. 8  illustrates a bottom plan view of the slider illustrated in  FIG. 6  including streamlines of airflow. 
           [0014]      FIG. 9  illustrates a bottom plan view of a slider according to yet another embodiment. 
           [0015]      FIG. 10  illustrates a bottom perspective view of the slider illustrated in  FIG. 9 . 
           [0016]      FIG. 11  illustrates a bottom plan view of the slider illustrated in  FIG. 9  including streamlines of airflow. 
       
    
    
     DETAILED DESCRIPTION 
       [0017]    Embodiments described herein include a slider having a slider body with a trailing edge and a leading edge. To minimize the accumulation of lubricant on the slider body from the data storage medium, nozzle features are included on the bottom of the slider body. Each nozzle feature includes both a convergent portion and a divergent portion. The convergent portions are located in closer proximity to the trailing edge than the divergent portions. 
         [0018]      FIG. 1  illustrates a perspective view of exemplary components of a data storage device including a head stack assembly  100  and date storage medium  102 . Medium  102  stores information on a plurality of circular, concentric data tracks and is mountable to a spindle motor assembly that can rotate medium  102  and cause its data surfaces to pass under respective bearing slider surfaces. As illustrated, each surface of medium  102  has an associated header or slider  104  and  105 , which carries transducers that communicate with a surface of medium  102 . 
         [0019]    Each slider  104  and  105  is supported by a head gimbal assembly (HGA)  106  and  107 , which are in turn attached to an actuator arm  108  and  109  of an actuator mechanism  110  to form a Head Stack Assembly (HSA)  100 . Actuator mechanism  110  is rotated about a shaft  111  by a voice coil motor  112 , which is controlled by servo control circuitry. Voice coil motor  112  rotates actuator mechanism  110  to position sliders  104  and  105  relative to desired data tracks between an inner diameter  114  and an outer diameter  116  of medium  102 . 
         [0020]    Before describing detailed embodiments of sliders that have lubricant control features, an overview of lubricant accumulation is discussed. Lubricant on a surface of a storage medium or rotating disc acts as a protective coating for preventing corrosion to the magnetic layers lying beneath its surface. During the operation of a data storage device, the bearing of the slider flies over the storage medium or disc. In this process, the bearing interacts with the lubricant coating on the medium or disc, the effects of which can be seen as various signatures on the head-medium interface. Some of these interactions are mechanically driven due to the shear on the medium, such as air-shear. One common signature is due to the mechanical lube pickup when the lubricant rips off the disc under high air-shear at the trailing edge (TE) of the slider and then subsequently pulls through the TE of the slider because of the existing backflow in that region (i.e., negative pressure gradients at the TE). The lube that enters the slider in this manner can accumulate in stagnation or low-velocity zones and can cause significant read/write performance disruptions. Although the reverse flow from the TE of the slider should not be eliminated because of strategies for forming negative pressure in the cavities of the air-bearing, the bearing features can be tailored to control the forward and reverse flow on the slider and minimize lube accumulation regions. This disclosure focuses on one such feature, namely, an in-plane nozzle-like feature for mitigating the effect of the lube flow from the TE and reducing accumulation zones. 
         [0021]      FIG. 2  illustrates an enlarged bottom plan view of a slider  204  under one embodiment. Slider  204  includes a slider body  218  having a leading edge  220 , a trailing edge  222 , an outer side edge  224  and an inner side edge  226 . Edge  224  is defined as an outer side edge because it is oriented towards the outer diameter of a data storage medium when the slider  204  is attached to an HSA, such as HSA  100  illustrated in  FIG. 1 . Edge  226  is defined as an inner side edge because it is oriented towards the inner diameter of a data storage medium when the slider is attached to an HSA, such as HSA  100  illustrated in  FIG. 1 . 
         [0022]    Slider  204  includes an outer rail  228 , an inner rail  230  and a center rail  232 . Outer rail  228  has an inner edge  234  and an outer edge  235 . Outer rail  228  is positioned between trailing edge  222  and leading edge  220  and is adjacent outer side edge  224  of slider body  218 . Inner rail  230  has an inner edge  236  and an outer edge  237 . Inner rail  230  is positioned between trailing edge  222  and leading edge  220  and is adjacent inner side edge  226  of slider body  218 . Center rail  232  is also positioned between trailing edge  222  and leading edge  220  of slider body  218  and positioned between and spaced apart from outer rail  228  and inner rail  230 . Defined between inner edge  234  of outer rail  228  and an edge of center rail  232  is a first cavity having a cavity surface or floor  238 . Defined between inner edge  236  of inner rail  230  and an edge of center rail  232  is a second cavity having a cavity surface of floor  239 . A portion of each of outer rail  228 , inner rail  230  and center rail  232  includes a bearing surface, while other portions of each of outer rail  228 , inner rail  230  and center rail  232  include step surfaces. Outer rail  228 , inner rail  230  and center rail  232  all protrude from cavity surfaces or cavity floors  238  and  239 . 
         [0023]      FIG. 3  illustrates an enlarged bottom perspective view of slider  204 . As illustrated, outer rail  228  includes bearing surface  240  and step surfaces  242  and  243 . Inner rail  230  includes bearing surface  244  and step surfaces  246  and  247 . Center rail  232  includes bearing surface  248  and step surfaces  250  and  251 . Bearing surfaces  240 ,  244  and  248  are defined by a bearing surface height  252 . Bearing surface height  252  is the distance from which bearing surfaces  240 ,  244  and  248  of outer rail  228 , inner rail  230  and center rail  232  protrude from cavity surfaces  238  and  239  of slider body  218 . Step surfaces  242 ,  243 ,  246 ,  247 ,  250  and  251  are defined by a step surface height  253 . Step surface height  253  is the distance from which step surfaces  242 ,  243 ,  246 ,  247 ,  250  and  251  protrude from cavity surfaces  238  and  239 . As illustrated, bearing surface height  252  is greater than step surface height  253 . 
         [0024]    With reference back to  FIG. 2 , bearing surface  240  of outer rail  228  includes an outer leg  254  and an inner leg  255 . Outer leg  254 , inner leg  255  and step surface  243  together define an outer rail channel  256 . Bearing surface  244  of inner rail  230  includes an outer leg  258  and an inner leg  259 . Outer leg  258 , inner leg  259  and step surface  247  define an inner rail channel  260 . In one embodiment, outer leg  254  and inner leg  255  of outer rail  228  are coupled together at an outer channel dam  261  ( FIG. 2 ). In another embodiment, outer leg  258  and inner leg  259  of inner rail  230  are coupled together at an inner channel dam  262  ( FIG. 2 ). 
         [0025]    Outer rail channel  261  includes a first end  263  ( FIG. 2 ) and a second end  264  ( FIG. 2 ). First end  263  of outer rail channel  256  is located at outer channel dam  261 , while second end  264  of outer rail channel  261  is in fluidic communication with outer side edge  224  of slider body  218 . Inner rail channel  260  includes a first end  265  ( FIG. 2 ) and a second end  266  ( FIG. 2 ). First end  265  of inner rail channel  260  is located at inner channel dam  262 . Second end  266  of inner rail channel  260  is in fluidic communication with inner side edge  226  of slider body  218 . 
         [0026]    Bearing surface  240  located at bearing surface height  252  of outer rail  228  is an outer pressurization surface having an above-ambient fluid pressure when slider  204  is in flight. Airflow (or other type of fluid) enters outer rail channel  256  at second end  264 . Airflow is dammed by outer channel dam  261  and provides bearing surface  240  or the outer pressurization surface with the above-ambient fluid pressure. Bearing surface  244  located at bearing surface height  252  of inner rail  230  is an inner pressurization surface having an above-ambient fluid pressure when slider  204  is in flight. Airflow (or other type of fluid) enters inner rail channel  260  at second end  266 . Air is dammed by inner channel dam  262  and provides bearing surface  244  or the inner pressurization surface with the above-ambient fluid pressure. While an above-ambient fluid pressure at the outer pressurization surface  240  and at the inner pressurization surface  244  provides slider body  218  with the desired flying stiffness, it also creates backflow in cavity surfaces  238  and  239  and thereby negative pressure gradients at trailing edge  222 . As described above, negative pressure gradients at trailing edge  222  can cause lubricant from the surface of a data storage medium to pull through trailing edge  222  and accumulate in stagnation or low-velocity zones. Therefore, slider  204  includes nozzle features for reducing lubricant accumulation zones. 
         [0027]    As illustrated in  FIGS. 2 and 3 , slider  204  includes a nozzle feature or step feature  268  in the first cavity defined by cavity surface  238  and a nozzle feature or step feature  269  in the second cavity defined by cavity surface  239 . Nozzle features  268  and  269  are located a spaced distance  270  from trailing edge  222 . Nozzle feature  268  is located separate from and between outer rail  228  and center rail  232  and includes step surface  272 . Nozzle feature  269  is located separate from and between inner rail  230  and center rail  232  and includes step surface  273 . Like step surfaces  242 ,  243 ,  246 ,  247 ,  250  and  251 , step surfaces  272  and  273  protrude from cavity surfaces  238  and  239  by step surface height  253 . 
         [0028]      FIG. 4  illustrates an enlarged perspective view of either nozzle feature  268  or nozzle feature  269 . Nozzle features  268  and  269  are rhombus-like in shape and include four sides  274 ,  275 ,  276  and  277 . Sides  274  and  275  intersect to form a trailing edge  278  and sides  276  and  277  intersect to form a leading edge  279 . Together side  274 , side  275  and trailing edge  278  form a convergent portion  280  and together side  276 , side  277  and leading edge  279  form a divergent portion  281 . Trailing edge  278  and therefore convergent portion  280  of nozzle features  268  and  269  are located in closer proximity to trailing edge  222  of slider  204  than leading edge  279  and therefore divergent portion  281 . Furthermore, as illustrated in  FIGS. 2-4 , sides  276  and  277  of divergent portion  281  includes lengths  282  that are greater than lengths  283  of sides  274  and  275  of convergent portion  280 . 
         [0029]      FIG. 5  illustrates exemplary streamlines of airflow in the bottom plan view of slider  204 . Divergent portion  281  of nozzle features  268  and  269  curls the backflow of fluid coming from trailing edge  222  back toward trailing edge  222 . Convergent portion  280  of nozzle features  268  and  269  speed up or increase the velocity of the forward flow of fluid (i.e., airflow directed toward trailing edge  222 ) in the cavities. Both convergent portion  280  and divergent portion  281  act to prevent stagnation zones from occurring in the trailing edge part of slider body  218  and therefore prevent lubricant accumulation. As illustrated in the oval circles illustrated in  FIG. 5 , stagnation regions are broken by nozzle features  268  and  269  and actually reverse the backflow to go back toward trailing edge  222 . In addition and as illustrated in the rectangular boxes illustrated in  FIG. 5 , more flow travels toward trailing edge  222  with the use of nozzle features  268  and  269  and stepper features  286  and  287 . 
         [0030]    As illustrated in  FIGS. 2 and 3 , slider  204  also includes skew-invariant bleeding stopper features  284  and  285 . Stopper feature  284  is an extension of bearing surface  240  of outer rail  228  and stopper feature  285  is an extension of bearing surface  244  of inner rail  230  and therefore located at the same height  252  as bearing surfaces  240  and  244 . More specifically, stopper feature  284  is an extension of outer leg  254  of outer rail  228  and stopper feature  285  is an extension of outer leg  248  of inner rail  230 . Stopper feature  284  extends in alignment from outer leg  254  toward trailing edge  222  from outer channel dam  261  and is adjacent to outer edge  235  of outer rail  228 . Stopper feature  285  extends in alignment from outer leg  258  toward trailing edge  222  from inner channel dam  262  and is adjacent outer edge  237  of inner rail  230 . Stopper features  284  and  285  reduce bleeding due to the cross flow of fluid or air from the outer edges  235  and  237  of rails  228  and  230  or side edges  224  and  226  of slider body  218 . In other words, stopper features  284  and  285  prevent fluid from outer edges  235  and  237  of outer rail  228  and inner rail  230  from interacting with nozzle features  268  and  269  so that nozzle feature  268  and  269  are allowed to function consistently across radial and skew angles with respect to a storage medium during a seek operation. 
         [0031]    As illustrated in  FIGS. 2 and 3 , slider  204  also includes converging surfaces  286  and  287  on outer rail  228  and inner rail  230 . Converging surface  286  is included as part of step surface  242  of outer rail  228  and converging surface  287  is included as part of step surface  246  of inner rail  230 . More specifically, converging surfaces  286  and  287  shape the inner edges of stepper surfaces  242  and  246  to provide another converging surface for speeding up the upstream flow of fluid or air to trailing edge  222 . As illustrated in  FIG. 2 , the converging surfaces  286  and  287  begin at the same distance from trailing edge  222  as convergent portion  280  of nozzle features  268  and  269 . 
         [0032]      FIG. 6  illustrates an enlarged bottom plan view of a slider  304  under one embodiment. Slider  304  includes a slider body  318  having a leading edge  320 , a trailing edge  322 , an outer side edge  324  and an inner side edge  326 . Edge  324  is defined as an outer side edge because it is oriented towards the outer diameter of a data storage medium when the slider  304  is attached to an HSA, such as HSA  100  illustrated in  FIG. 1 . Edge  326  is defined as an inner side edge because it is oriented towards the inner diameter of a data storage medium when the slider is attached to an HSA, such as HSA  100  illustrated in  FIG. 1 . 
         [0033]    Slider  304  includes an outer rail  328 , an inner rail  330  and a center rail  332 . Outer rail  328  has an inner edge  334  and an outer edge  335 . Outer rail  328  is positioned between trailing edge  322  and leading edge  320  and is adjacent outer side edge  324  of slider body  318 . Inner rail  330  has an inner edge  336  and an outer edge  337 . Inner rail  330  is positioned between trailing edge  322  and leading edge  320  and is adjacent inner side edge  326  of slider body  318 . Center rail  332  is also positioned between trailing edge  322  and leading edge  320  of slider body  318  and positioned between and spaced apart outer rail  328  and inner rail  330 . Defined between inner edge  334  of outer rail  328  and an edge of center rail  332  is a first cavity having a cavity surface or floor  338 . Defined between inner edge  336  of inner rail  330  and an edge of center rail  332  is a second cavity having a cavity surface or floor  339 . A portion of each of outer rail  328 , inner rail  330  and center rail  332  includes a bearing surface, while other portions of each of outer rail  328 , inner rail  330  and center rail  332  include step surfaces. Outer rail  328 , inner rail  330  and center rail  332  all protrude from cavity surfaces or cavity floors  338  and  339 . 
         [0034]      FIG. 7  illustrates an enlarged bottom perspective view of slider  304 . As illustrated, outer rail  328  includes bearing surface  340  and step surfaces  342  and  343 . Inner rail  330  includes bearing surface  344  and step surfaces  346  and  347 . Center rail  332  includes bearing surface  348  and step surfaces  350  and  351 . Bearing surfaces  340 ,  344  and  348  are defined by a bearing surface height  352 . Bearing surface height  352  is the distance from which bearing surfaces  340 ,  344  and  348  of outer rail  328 , inner rail  330  and center rail  332  protrude from cavity surfaces  338  and  339  of slider body  318 . Step surfaces  342 ,  343 ,  346 ,  347 ,  350  and  351  are defined by a step surface height  353 . Step surface height  353  is the distance from which step surfaces  342 ,  343 ,  346 ,  347 ,  350  and  351  protrude from cavity surfaces  338  and  339 . As illustrated, bearing surface height  352  is greater than step surface height  353 . 
         [0035]    With reference back to  FIG. 6 , bearing surface  340  of outer rail  328  includes an outer leg  354  and an inner leg  355 . Outer leg  354 , inner leg  355  and step surface  343  together define an outer rail channel  356 . Bearing surface  344  of inner rail  330  includes an outer leg  358  and an inner leg  359 . Outer leg  358 , inner leg  359  and step surface  347  define an inner rail channel  360 . In one embodiment, outer leg  354  and inner leg  355  of outer rail  328  are coupled together at an outer channel dam  361  ( FIG. 6 ). In another embodiment, outer leg  358  and inner leg  359  of inner rail  330  are coupled together at an inner channel dam  362  ( FIG. 6 ). 
         [0036]    Outer rail channel  361  includes a first end  363  ( FIG. 6 ) and a second end  364  ( FIG. 6 ). First end  363  of outer rail channel  356  is located at outer channel dam  361 , while second end  364  of outer rail channel  361  is in fluidic communication with outer side edge  324  of slider body  318 . Inner rail channel  360  includes a first end  365  ( FIG. 6 ) and a second end  366  ( FIG. 6 ). First end  365  of inner rail channel  360  is located at inner channel dam  362 . Second end  366  of inner rail channel  360  is in fluidic communication with inner side edge  326  of slider body  318 . 
         [0037]    Bearing surface  340  located at bearing surface height  352  of outer rail  328  is an outer pressurization surface having an above-ambient fluid pressure when slider  304  is in flight. Airflow (or other type of fluid) enters outer rail channel  356  at second end  364 . Airflow is dammed by outer channel dam  361  and provides bearing surface  340  or the outer pressurization surface with the above-ambient fluid pressure. Bearing surface  344  located at bearing surface height  352  of inner rail  330  is an inner pressurization surface having an above-ambient fluid pressure when slider  304  is in flight. Airflow (or other type of fluid) enters inner rail channel  360  at second end  366 . Air is dammed by inner channel dam  362  and provides bearing surface  344  or the inner pressurization surface with the above-ambient fluid pressure. While an above-ambient fluid pressure at the outer pressurization surface  340  and at the inner pressurization surface  344  provides slider body  318  with the desired flying stiffness, it also creates backflow in cavity surfaces  338  and  339  and thereby negative pressure gradients at trailing edge  322 . As described above, negative pressure gradients at trailing edge  322  can cause lubricant from the surface of a data storage medium to pull through trailing edge  322  and accumulate in stagnation or low-velocity zones. Therefore, slider  304  includes a plurality of nozzle features for reducing lubricant accumulation zones. 
         [0038]    As illustrated in  FIGS. 6 and 7 , slider  304  includes three nozzle features or step features  368 ,  369 ,  390  in the first cavity defined by cavity surface  338  and three nozzle features or step features  391 ,  392  and  393  in the second cavity defined by cavity surface  339 . All six nozzle features  368 ,  369 ,  390 ,  391 ,  392  and  393  are located a spaced distance from trailing edge  322 . For example, nozzle features  368 ,  369 ,  391  and  392  are located a spaced distance  370  from trailing edge  322 , while nozzle features  390  and  393  are located a spaced distance  394  from trailing edge  322 . Distance  394  is greater than distance  370 . In this way, each of nozzle features  368 ,  369  and  390  define a point of a triangle and each of nozzle features  391 ,  392  and  393  define a point of a triangle. Nozzle features  268 ,  269  and  290  are separate from each other and are located separate from and between outer rail  328  and center rail  332  and include step surface  372  ( FIG. 7 ). Nozzle features  391 ,  392  and  393  are separate from each other and are located separate from and between inner rail  330  and center rail  332  and include step surface  373  ( FIG. 7 ) Like step surfaces  342 ,  343 ,  346 ,  347 ,  350  and  351 , step surfaces  372  and  373  protrude from cavity surfaces  338  and  339  by step surface height  353  ( FIG. 7 ). 
         [0039]    Each of nozzle features  368 ,  369 ,  390 ,  391 ,  392  and  393  include a rhombus-like geometry similar to nozzle features  268  and  269  illustrated in  FIG. 4 . In particular,  FIG. 8  illustrates exemplary streamlines of airflow in the bottom plan view of slider  304 . As previously discussed, the divergent portions of nozzle features  368 ,  369 ,  390 ,  391 ,  392  and  393  curl the backflow of fluid coming from trailing edge  322  back toward trailing edge  322 . The convergent portions of nozzle features  368 ,  369 ,  390 ,  391 ,  392  and  393  speed up or increase the velocity of the forward flow of fluid (i.e., airflow directed toward trailing edge  322 ) in the cavities. Both the divergent portions and convergent portions act to prevent stagnation zones from occurring in the trailing edge part of slider body  218  and therefore prevent lubricant accumulation. As illustrated in the circles illustrated in  FIG. 8 , stagnation regions are broken by nozzle features  368 ,  369 ,  390 ,  391 ,  392  and  393  and actually reverse the backflow to go back toward trailing edge  322 . 
         [0040]      FIG. 9  illustrates an enlarged bottom plan view of a slider  404  under yet another embodiment. Slider  404  includes a slider body  418  having a leading edge  420 , a trailing edge  422 , an outer side edge  424  and an inner side edge  426 . Edge  424  is defined as an outer side edge because it is oriented towards the outer diameter of a data storage medium when the slider  404  is attached to an HSA, such as HSA  100  illustrated in  FIG. 1 . Edge  426  is defined as an inner side edge because it is oriented towards the inner diameter of a data storage medium when the slider is attached to an HSA, such as HSA  100  illustrated in  FIG. 1 . 
         [0041]    Slider  404  includes an outer rail  428 , an inner rail  430  and a center rail  432 . Outer rail  428  has an inner edge  434  and an outer edge  435 . Outer rail  428  is positioned between trailing edge  422  and leading edge  420  and is adjacent outer side edge  424  of slider body  418 . Inner rail  430  has an inner edge  436  and an outer edge  437 . Inner rail  430  is positioned between trailing edge  422  and leading edge  420  and is adjacent inner side edge  426  of slider body  418 . Center rail  232  is also positioned between trailing edge  422  and leading edge  420  of slider body  418  and positioned between and spaced apart from outer rail  428  and inner rail  430 . Defined between inner edge  434  of outer rail  428  and an edge of center rail  432  is a first cavity having a cavity surface or floor  438 . Defined between inner edge  436  of inner rail  430  and an edge of center rail  432  is a second cavity having a cavity surface or floor  439 . A portion of each of outer rail  428 , inner rail  430  and center rail  432  includes a bearing surface, while other portions of each of outer rail  428 , inner rail  430  and center rail  432  include step surfaces. Outer rail  428 , inner rail  430  and center rail  432  all protrude from cavity surfaces or cavity floors  438  and  439 . 
         [0042]      FIG. 10  illustrates an enlarged bottom perspective view of slider  404 . As illustrated, outer rail  428  includes bearing surface  440  and step surfaces  442  and  443 . Inner rail  430  includes bearing surface  444  and step surfaces  446  and  447 . Center rail  432  includes bearing surface  448  and step surfaces  450  and  451 . Bearing surfaces  440 ,  444  and  448  are defined by a bearing surface height  452 . Bearing surface height  452  is the distance from which bearing surfaces  440 ,  444  and  448  of outer rail  428 , inner rail  430  and center rail  432  protrude from cavity surfaces  438  and  439  of slider body  418 . Step surfaces  442 ,  443 ,  446 ,  447 ,  450  and  451  are defined by a step surface height  453 . Step surface height  453  is the distance from which step surfaces  442 ,  443 ,  446 ,  447 ,  450  and  451  protrude from cavity surfaces  438  and  439 . As illustrated, bearing surface height  452  is greater than step surface height  453 . 
         [0043]    With reference back to  FIG. 9 , bearing surface  440  of outer rail  428  includes an outer leg  454  and an inner leg  455 . Outer leg  454 , inner leg  455  and step surface  443  together define an outer rail channel  456 . Bearing surface  444  of inner rail  430  includes an outer leg  458  and an inner leg  459 . Outer leg  458 , inner leg  459  and step surface  447  define an inner rail channel  460 . In one embodiment, outer leg  454  and inner leg  455  of outer rail  428  are coupled together at an outer channel dam  461  ( FIG. 9 ). In another embodiment, outer leg  458  and inner leg  459  of inner rail  40  are coupled together at an inner channel dam  462  ( FIG. 9 ). 
         [0044]    Outer rail channel  461  includes a first end  463  ( FIG. 9 ) and a second end  464  ( FIG. 9 ). First end  463  of outer rail channel  456  is located at outer channel dam  461 , while second end  464  of outer rail channel  461  is in fluidic communication with outer side edge  424  of slider body  418 . Inner rail channel  460  includes a first end  465  ( FIG. 9 ) and a second end  466  ( FIG. 9 ). First end  465  of inner rail channel  460  is located at inner channel dam  462 . Second end  466  of inner rail channel  460  is in fluidic communication with inner side edge  426  of slider body  418 . 
         [0045]    Bearing surface  440  located at bearing surface height  452  of outer rail  428  is an outer pressurization surface having an above-ambient fluid pressure when slider  404  is in flight. Airflow (or other type of fluid) enters outer rail channel  456  at second end  464 . Airflow is dammed by outer channel dam  461  and provides bearing surface  440  or the outer pressurization surface with the above-ambient fluid pressure. Bearing surface  444  located at bearing surface height  452  of inner rail  40  is an inner pressurization surface having an above-ambient fluid pressure when slider  404  is in flight. Airflow (or other type of fluid) enters inner rail channel  460  at second end  466 . Air is dammed by inner channel dam  462  and provides bearing surface  444  or the inner pressurization surface with the above-ambient fluid pressure. While an above-ambient fluid pressure at the outer pressurization surface  440  and at the inner pressurization surface  444  provides slider body  418  with the desired flying stiffness, it also creates backflow in cavity surfaces  438  and thereby negative pressure gradients at trailing edge  422 . As described above, negative pressure gradients at trailing edge  422  can cause lubricant from the surface of a data storage medium to pull through trailing edge  422  and accumulate in stagnation or low-velocity zones. Therefore, slider  404  includes nozzle features for reducing lubricant accumulation zones. 
         [0046]    As illustrated in  FIGS. 9 and 10 , slider  404  includes a nozzle feature or step feature  468  in the first cavity defined by cavity surface  438  and a nozzle feature or step feature  469  in the second cavity defined by cavity surface  439 . Nozzle features  468  and  469  are located a spaced distance  470  from trailing edge  422 . Nozzle feature  468  is located separate from and between outer rail  428  and center rail  432  and includes step surface  472 . Nozzle feature  469  is located separate from and between inner rail  430  and center rail  432  and includes step surface  473 . Like step surfaces  442 ,  443 ,  446 ,  447 ,  450  and  451 , step surfaces  472  and  473  protrude from cavity surfaces  438  by step surface height  453  ( FIG. 10 ). 
         [0047]    Each of nozzle features  468  and  469  include a rhombus-like geometry and are substantially similar to nozzle features  268  and  269  illustrated in  FIG. 4 . In particular,  FIG. 11  illustrates exemplary streamlines of airflow in the bottom plan view of slider  404 . As previously discussed, the divergent portions of nozzle features  468  and  469  curl the backflow of fluid coming from trailing edge  422  back toward trailing edge  422 . The convergent portions of nozzle features  468  and  469  speed up or increase the velocity of the forward flow of fluid (i.e., airflow directed toward trailing edge  422 ) in the cavities. Both the divergent portions and convergent portions act to prevent stagnation zones from occurring in the trailing edge part of slider body  418  and therefore prevent lubricant accumulation. As illustrated in the circles illustrated in  FIG. 11 , stagnation regions are broken by nozzle features  468  and  469  and actually reverse the backflow to go back toward trailing edge  422 . 
         [0048]    As illustrated in  FIGS. 9 and 10 , slider  404  also includes skew-invariant bleeding stopper features  484  and  485 . Stopper feature  484  is an extension of bearing surface  440  of outer rail  428  and stopper feature  485  is an extension of bearing surface  444  of inner rail  430  and therefore located at the same height  452  as bearing surfaces  440  and  444 . More specifically, stopper feature  484  is an extension of outer leg  454  of outer rail  428  and stopper feature  485  is an extension of outer leg  448  of inner rail  430 . Rather than stopper features  484  and  485  extending in alignment from the outer legs  454  and  458  and toward trailing edge  422  from the outer channel dams  461  and  462  as described in regards to the  FIGS. 2-5 , stopper features  484  and  485  follow and are adjacent to inner edges  434  and  436  of outer and inner rails  428  and  430  from outer legs  454  and  458  toward trailing edge  422 . Stopper features  484  and  485  reduce bleeding due to the cross flow of fluid or air from the outer edges  435  and  437  of rails  428  and  430  or side edges  424  and  426  of slider body  418 . In other words, stopper features  484  and  485  prevent fluid from outer edges  435  and  437  of outer rail  428  and inner rail  430  from interacting with nozzle features  468  and  469  so that nozzle features  468  and  469  are allowed to function consistently across radial and skew angles with respect to a storage medium during a seek operation. 
         [0049]    Although the subject matter has been described in language specific to structural features and/or methodological acts, it is to be understood that the subject matter defined in the appended claims is not necessarily limited to the specific features or acts described above. Rather, the specific features and acts described above are disclosed as example forms of implementing the claims.