Method and apparatus for loading a magnetic head onto a magnetic disk

A spinstand head-loading mechanism of a magnetic tester includes a protector bar and a lift arm which control the loading and unloading operations of a magnetic head, as part of a head-gimbal assembly, with respect to a magnetic disk. A series of actuators control the engagement and disengagement of protector bar and lift arm with a head-gimbal assembly that includes read/write elements as part of a slider. The protector bar is driven in a Y-axis direction by an actuator, while the head-gimbal assembly is disposed in an X-axis direction, orthogonally to the Y-axis. The lift arm is also driven in the Y-axis direction by an actuator, but is also driven in a Z-axis direction by a different actuator. Before testing, the head of the head-gimbal assembly is loaded onto a magnetic disk. To accomplish this, the head-gimbal assembly is initially installed on the head-loading mechanism. During this process and when the head-gimbal assembly is outside of the magnetic disk area, the protector bar is used to support a suspension member of the head-gimbal assembly. To prevent damage to the head-gimbal assembly, the protector bar is formed from a plastic material having a low coefficient of friction. Ultimately, the lift arm takes over control of the head-gimbal assembly and the protector bar disengages the suspension member. The lift arm then lowers the head toward the disk until its "flying height" is established. Then the lift arm retracts. The head is unloaded by reversing these steps.

FIELD OF THE INVENTION
 The present invention relates to magnetic head and disk testers, and in
 particular, to a method and apparatus for loading a magnetic head onto a
 magnetic disk accurately and smoothly, so as to avoid damage to the
 magnetic head and the magnetic disk during the loading operation.
 BACKGROUND OF THE INVENTION
 A magnetic head and disk tester is an instrument that is used for testing
 the characteristics of magnetic heads and disks. Tester parameters may
 include signal-to-noise ratio, bit error rate, and the like. A tester
 typically includes two main assemblies, an electro-mechanical assembly
 that performs movements of a head with respect to a disk, and an
 electronic assembly that is responsible for measurements, calculations,
 and analysis of the measured data. The electro-mechanical assembly of the
 tester is known as a spinstand. The spinstand generally simulates the
 motions of the head with respect to the disk that occur in, for example, a
 hard disk drive. The spinstand includes a support and rotational driver
 for the magnetic disk. The spinstand also includes an assembly of
 components which effects movement and placement of a magnetic head
 relative to the rotating, or spinning, magnetic disk, often referred to as
 a head-loading mechanism. Since the magnetic head and disk are very
 fragile by their nature, it is important that the magnetic head and disk
 never actually come into physical contact during operation. However, the
 magnetic head and disk are positioned in extremely close proximity to each
 other under such conditions to support magnetic read and write operations.
 Therefore, precise placement of the magnetic head relative to the magnetic
 disk is essential to avoid damaging contact between the two.
 In a typical spinstand configuration, the magnetic head is part of a
 head-gimbal assembly which disposes the magnetic head over the magnetic
 disk (but separated by aerodynamic forces) and is moved under the control
 of the head-loading mechanism. FIG. 1 shows a typical prior art
 head-gimbal assembly (HGA) 15, which includes a slider 10 disposed at a
 distal end of an elongated resilient suspension member 12 and a planar
 mounting portion 14 formed at its proximal end. Generally the suspension
 member 12 extends along a suspension axis S. The suspension axis S is
 angularly offset with respect to the planar portion 14. Slider 10 includes
 the magnetic head read and write elements of head-gimbal assembly 15.
 Disposed along the underside of suspension member 12, typically, are
 electrical wires 16 which carry read and write data signals to and from
 the magnetic head. In operation, the head-gimbal assembly 15 is secured to
 a cartridge, which in turn is secured to and manipulated by head-loading
 mechanism components to accomplish loading of the magnetic head over/onto
 the spinning magnetic disk.
 To effect loading, the head-loading mechanism advances the slider toward a
 magnetic medium-bearing surface of the spinning disk. The resilience
 characteristic of the suspension is selected so that the slider is
 spring-biased toward the disk but kept separated form that disk due to air
 flow between the head and the spinning disk. The separation between the
 head and disk surface is referred to in art as the "flying height".
 Thus, for the configuration of FIG. 1, suspension member 12 biases slider
 10 toward the magnetic disk. When slider 10 is positioned near the
 spinning magnetic disk, an "air bearing" is formed between the slider 10
 and the magnetic disk, and aerodynamic forces on the slider 10 counter the
 bias of the suspension member 12, causing the slider 10 to remain
 suspended just above the rotating magnetic disk, separated by a
 predetermined small gap (or "flying height") between slider 10 and the
 disk surface. The actual positioning of slider 10 relative to the magnetic
 disk, and the associated manipulation of the suspension member 12 are
 accomplished by various components of the head-loading mechanism. For
 example, in various prior art embodiments, arms or bars are used to
 control the suspension member 12 as the slider 10 is positioned near, or
 loaded onto, the disk.
 In a typical prior art head-loading mechanism, the mounting portion 14 of
 head-gimbal assembly 15 is secured to a flat surface of a rigid block,
 known as a cartridge. The cartridge (with the head-gimbal assembly
 attached) is first affixed to a mating surface of the head-loading
 mechanism, for example using a pneumatic coupling. As part of the loading
 operation, the head-loading mechanism is then moved close to a magnetic
 disk and the slider 10 (and its read and write elements) is positioned
 over the disk such that the slider remains close to the disk, but is not
 brought into close proximity with the disk surface at this point. The disk
 may or may not be spinning during this part of the loading operation,
 depending on the particular design and configuration of the head and disk.
 The subsequent loading and testing operations depend on the type of
 head-loading mechanism incorporated by the spinstand of the tester. Those
 loading and test operations generally include lowering the head toward the
 disk to establish the suspension-air bearing force balance (i.e. the
 "loading") followed by moving the head through a series of predetermined
 test positions relative to the disk and reading and writing data (i.e. the
 "testing").
 A portion of a prior art spinstand head-loading mechanism 20 is shown FIG.
 2 as an example of such mechanisms. A head-gimbal assembly of the type
 shown in FIG. 1, and a cartridge 22 are mounted on a mating surface of the
 head loading mechanism 20 of the spinstand so that the slider 10 is
 opposite but grossly spaced apart, from the upper surface of spinning
 magnetic disk 26. The suspension member 12 is angled downward toward disk
 26, with electrical wires 16 disposed on the underside of suspension
 member 12. The mounting portion 14 of the suspension member 12 is secured
 to the cartridge 22 which is secured in turn to head loading mechanism 20.
 In this exemplary prior art configuration, a metal arm 24 is disposed
 under the suspension member 12 such that its upper surface engages the
 underside of suspension member 12 between the slider 10 and portion 14,
 ensuring that slider 10 is significantly separated from disk 26. Arm 24 is
 movable in the X and Y directions, as illustrated in FIG. 2. In operation
 after the disk 26 is spinning, and with arm 24 in its extended position so
 that it underlies the suspension member 12, and with slider 10 positioned
 over disk 26 (all as shown in FIG. 2), arm 24 is lowered until slider 10
 approaches its flying height and suspension member 12 separates from arm
 24. Then arm 24 is retracted and testing begins. This prior art
 configuration has several significant problems. First during the loading
 operation, slider 10 moves on an arc and therefore the motion can be
 controlled more accurately and smoothly if arm 24 contacts suspension
 member 12 at a point close to slider 10. However, that is problematic
 because since suspension 12 is originally at an angle to mounting portion
 14 of the head, arm 24 can not be positioned very close to slider 10, as
 this would cause arm 24 to contact and damage slider 10 as cartridge 22
 (with the attached head-gimbal assembly) is installed on head loading
 mechanism 20. During installation of cartridge 22 on head loading unit 20,
 arm 24 remains in its position and therefore lifts suspension element 12
 as cartridge 22 makes firm contact with head loading mechanism 20. Again,
 because suspension 12 is originally at an angle to mounting portion 14 of
 the head-gimbal assembly, and arm 24 is made of metal, this operation
 typically causes arm 24 to scratch the side of suspension 12 where it
 contacts arm 24. In some types of heads, this results in damage to
 electrical wires 16 underneath suspension 12.
 Another form of prior art spinstand head-loading mechanism is shown in FIG.
 3. In that configuration, a head cartridge is initially mounted to head
 loading mechanism 20. In this configuration, lift bar 24 (which has an
 inclined profile wedge at its distal end, and which is retractable in the
 X-direction) is positioned between slider 10 and the top surface of disk
 surface 26, where the thickness of the tapered tip of the wedge is less
 than the gap between suspension member 12 and disk surface 26 when the
 head is loaded on the disk. As a wedge is inserted between suspension
 member 12 and the disk 26, the slider 10 is lifted off of the disk 26, and
 as lift bar 24 is pulled away, slider 10 moves bar 24 closer to the disk,
 until it starts flying over surface of disk 26. There is a gap between bar
 24 and disk surface 26 at all times in order to avoid contact between the
 two. Due to the high precision and small dimensions (especially thickness)
 of bar 24, it can not be manufactured of a plastic material. During
 installation of a cartridge 22 (with the attached head-gimbal assembly) on
 head loading mechanism 20, the wedge portion of arm 24 remains in its
 position and therefore lifts suspension member 12 as cartridge 22 makes
 firm contact with the mounting surface on head loading mechanism 20.
 Because suspension member 12 is originally at an angle to mounting portion
 14 of the head-gimbal assembly, this operation can cause arm 24 to scratch
 the side of suspension member 12 where it contacts arm 24. In some types
 of heads, this results in damage to electrical wires 16 underneath
 suspension 12.
 Another prior art head loading assembly is shown in FIG. 4. That assembly
 addresses the potential for damage to electrical wires 16 of the
 head-gimbal assembly. In that prior art assembly, load and unload
 operations are achieved by rotating a mounting block 43 (together with the
 head-gimbal assembly) with respect to cartridge 22, about an axis 44
 parallel to the top surface of disk 26. There are no bars or wedges that
 contact the suspension during these operations. During loading operation,
 the head loading mechanism 20 is brought close to the disk 26 such that
 the slider, 10 remains over the disk, and mounting block 43 together with
 the head-gimbal assembly, is rotated until mounting portion 14 is parallel
 to the disk 26, at a specified distance from the surface of disk 26.
 During this rotation, due to the initial angle between suspension member
 12 and mounting portion 14 of the head-gimbal assembly, slider 10 contacts
 the disk before mounting portion 14 becomes parallel to the disk 26, and
 therefore may cause scratches and pits on disk surface 26 an slider 10.
 During unloading operation, mounting block 43 is rotated in the opposite
 direction compared to the loading operation. As slider 10 is lifted off of
 the disk 26, suspension member 12 can vibrate vertically since it is not
 supported at a point close to slider 10. This may cause scratches and pits
 on surface 26 and slider 10.
 In order to overcome some of the problems associated with the above
 described prior art head loading assemblies, more recent prior art
 suspension members are provided with a lifting tab at the distal end that
 extends beyond the slider. An exemplary prior art head-gimbal assembly 60
 of this form including a lift tab 51, is shown in FIG. 5. In FIG. 5,
 elements that correspond to elements in the assembly of FIG. 1, are
 identified with the same reference designations. In this form, the lifting
 tab 51 is used by the a head-loading mechanism of a spinstand to lower and
 lift suspension member 12 and, therefore, slider 10, during the loading
 and unloading operations. Lift tab 51 is typically located beyond slider
 50, as an extension of the suspension member 12, but very close to slider
 50. Like the head-gimbal assembly 15 of FIG. 1, the head-gimbal assembly
 15 of FIG. 5 also includes electrical wires 16 disposed at the underside
 of the suspension member 12.
 An example of a portion of a prior art head-loading mechanism of a
 spinstand incorporating head-gimbal assembly 15 of FIG. 5 is shown in FIG.
 6. In FIG. 6, the arm 24 is laterally displaced (compared with the
 location of the corresponding arm in FIG. 2). Mounting portion 14 of the
 suspension member 12 is secured to cartridge 22, which in turn is secured
 to head-loading mechanism 20. Again, suspension member 12 is biased toward
 a magnetic disk 26 mounted on the spinstand. Suspension member 12 is
 engaged by arm 24 at tab 51 and its motion (and slider 10) relative to
 disk 26 is controlled by the vertical (Y) direction arm 24. In such a
 spinstand, the problem of damaging electrical wires 16 is eliminated,
 since arm 24 does not physically interact with the underside of
 head-gimbal assembly 15 in the area of electrical wires 16. However, this
 form of head loader has a different problem. That is, as cartridge 22 and
 head-gimbal assembly 60 are installed on the head loading mechanism 20,
 due to the initial angular orientation of suspension member 12, toward
 disk 26, the tab is relatively close to disk 26. As a consequence, that
 lifting arm 24 may not reliably engage lift tab 51.
 For a particular type of head gimbal assembly, one of the above mentioned
 prior art head loading mechanisms may work better than another, but for
 certain types of heads each of them has one or more deficiencies, as
 described above. In older head and disk designs, the scratches and pits on
 the disk surface caused by the loading and unloading operations of such
 spinstands were within acceptable limits. However, as the head and disk
 technology progresses, there is an increasing need for higher precision
 and integrity of the head and disk components. Moreover, for certain types
 of head design, no prior art system is adequate.
 Accordingly, it is an object of the invention to provide a head loading
 apparatus and method that minimizes damage to heads and disks during
 loading.
 It is another object to provide a head loading apparatus and method that
 permits improved, minimal damaging loading without requiring special
 handling.
 SUMMARY OF THE INVENTION
 The present invention provides a head-loading mechanism of a magnetic
 tester that provides for smooth loading and unloading of a magnetic head
 onto a spinning magnetic disk of a spinstand, without damage to the head
 of a head-gimbal assembly, the magnetic disk, or other portions of the
 head-gimbal assembly, such as electrical wires. The head-gimbal assembly
 includes an elongated resilient suspension member having a mounting
 portion at one end and a slider, which includes the head read and write
 components, at the other end, and may include electrical wires disposed on
 its underside. A cartridge is affixed to the mounting portion, to form a
 single unit that can be tested. The unit, including a cartridge and an
 attached head-gimbal assembly, is referenced to herein as a cartridge/HGA
 assembly. The cartridge/HGA assembly is mounted to the head loading
 mechanism so that the long axis of the suspension member extends at least
 in part along an X axis parallel to the plane of the disk, and in part
 angled toward the plane of the disk.
 The preferred head-loading mechanism includes two head control mechanisms
 which support and control the slider and suspension member during loading
 and unloading operations. The first head control mechanism includes a
 protector bar which is secured to a first carriage that is slidably
 coupled to a first rail which is integral with a base plate, wherein the
 base plate provides the overall foundation of the head-loading mechanism.
 An actuator drives the protector bar along a Y-axis (orthogonal to the
 X-axis) via a shaft. The protector bar provides initial support for the
 suspension member, from underneath, as the cartridge together with the
 head-gimbal assembly is being secured to the head loading mechanism. The
 protector bar is formed from a material having a low coefficient of
 friction, to prevent damage to the head-gimbal assembly, including, but
 not limited to the electrical wires at the underside of the suspension
 member.
 The second head control mechanism includes a lift arm which engages the
 suspension member of the head-gimbal assembly and ultimately takes over
 control after the head-gimbal assembly has been secured to the
 head-loading mechanism. The lift arm is secured to a second carriage which
 is slidably coupled to a second rail that is integral with the base plate.
 A second actuator drives the lift arm in the Y-axis direction, parallel to
 the protector bar. The second carriage includes a third carriage to which
 the lift arm is directly coupled. The third carriage is driven by a third
 actuator to move the lift arm in a Z-axis direction, which is orthogonal
 to the X and Y-axes. The lift arm is first disposed beneath the suspension
 member and then moves away from the disk in the Z-axis direction to engage
 the suspension member and disengage the protector bar. The lift arm
 ultimately lowers the slider until it rests on the air bearing formed
 between the slider and the disk and then disengages the suspension member
 and retracts. The unloading operation is performed by reversing these
 steps.
 In a preferred form, the invention loads a slider of a cartridge/HGA
 assembly against a surface of a rotating magnetic disk, where the
 cartridge/HGA assembly includes (a) a cartridge having a suspension
 support surface on one side thereof, (b) a head-gimbal assembly including
 (i) an elongated, resilient suspension member extending along a suspension
 axis from a proximal end to a distal end, where a first side of the
 suspension member at said proximal end is affixed to the suspension
 support surface of the cartridge, and (ii) a slider including the read and
 write elements of the magnetic head. The slider is affixed to a second
 side of the suspension member at a point along the suspension axis between
 the distal end and the proximal end. This form of the invention includes a
 spindle and associated disk support assembly attached to a base on a
 spinstand. The spindle and support assembly support the disk in a circular
 locus in a disk plane, and rotate the disk in the disk locus about a spin
 axis perpendicular to the disk plane. A head loader assembly on the base
 includes a head support assembly, a lift arm, a protector bar and a
 driver/controller. The head loader assembly is slidable in a predetermined
 range of motion along a slide axis parallel to the disk plane. The head
 support assembly rigidly supports the cartridge (with the attached
 head-gimbal assembly) mounted thereon, whereby (1) the read write elements
 of the magnetic head are opposite the disk plane and at least in part of
 its range of motion, are opposite the disk locus, and (2) the suspension
 axis of the resilient suspension member is in a suspension plane
 perpendicular to the slide axis (i.e. a plane passing through the axis of
 suspension member, as that member).
 The lift arm is in a first locus, at least in part extending in a direction
 parallel to the slide axis and extending through the suspension plane. The
 lift arm is selectively moveable in the direction of the slide axis and in
 a direction of a lift axis perpendicular to the disk plane. The first
 locus is between the cartridge and the distal end of the suspension member
 of the head-gimbal assembly when those elements are mounted to the head
 support assembly.
 The protector bar is in a second locus, at least in part extending in a
 direction parallel to the slide axis and extending through the suspension
 plane. The protector arm is selectively movable in the direction of the
 slide axis, and has an upper surface made of a material with a relatively
 low coefficient of friction. That surface is located with respect to the
 portion of the head support assembly which supports the cartridge to
 ensure that the suspension member is deflected upward (from its nominally
 downward angled inclination) when the cartridge is mounted to the head
 support assembly with the protector bar is in the suspension plane and the
 lift arm is not in that plane. The second locus is between the first locus
 and the distal end of the suspension member when the cartridge and
 head-gimbal assembly are mounted to the head support assembly.
 In the preferred form, the driver/controller is operative prior to mounting
 of the cartridge and head-gimbal assembly to the support plate, to
 position the protector arm to extend through the suspension plane, and to
 position the lift arm outside that plane. Upon mounting the cartridge to
 the head support assembly, the suspension member is biased against the top
 surface of the protector bar. The driver/controller is operative following
 mounting of the cartridge to the head support assembly, to successively:
 (a) drive the lift arm in the direction of the slide axis to a position
 underlying the suspension member,
 (b) drive the lift arm in the direction of the lift axis until the lift arm
 engages the suspension member and lifts the suspension member from the top
 surface of the protector bar,
 (c) drive the protector bar in the direction of the slide axis so that the
 protector bar does not extend through the suspension plane,
 (d) position the head loading mechanism whereby the read and write elements
 of the magnetic head of the head-gimbal assembly overlie the disk locus,
 (e) drive the lift arm in the direction of the lift axis and toward the
 disk locus, until the suspension member disengages from the lift arm,
 (f) drive the lift arm in the direction of the slide axis so that the lift
 arm does not overlie the disk locus.

For the most part, and as will be apparent when referring to the figures,
 when an item is used substantially unchanged in more than one figure, it
 is identified by the same alphanumeric reference indicator in all figures.
 DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
 A preferred embodiment of a head-loading mechanism 85 of the invention
 shown (with respect to an X-Y-Z cartesian coordinate system) in FIG. 7 for
 a spinstand magnetic head and disk tester. The preferred embodiment is
 adapted for a head-gimbal assembly 84 which is substantially similar to
 that described with respect to FIG. 5, including resilient elongated
 suspension member 84A, a mounting portion, a slider 110, and a lifting tab
 84B. The head-gimbal assembly has its mounting portion affixed to a rigid
 cartridge 82, so that the head-gimbal assembly 84 and cartridge 82 form a
 single unit for testing. Other forms of cartridge and head-gimbal
 assemblies may be used as well.
 In FIG. 7, a base plate 80 provides a rigid foundation for head-loading
 mechanism 85 which is mounted to a spinstand (not shown) having a support
 for a magnetic disk, and rotational driver for that disk. The plate 80
 comprises three plate components 80A, 80B, and 80C. Plate component 80A
 serves as the foundation for a series of head control mechanisms which
 selectively manipulate a cartridge (with an attached head-gimbal assembly)
 to be mounted thereto. The main portion of plate component 80A extends in
 the direction of the Y-axis. A rectangular head-gimbal support plate
 component 80B extends from component plate 80A. An upper portion of plate
 component 80B is adapted to receive cartridge 82 and the head-gimbal
 assembly in a conventional manner, with the mounting area of head-gimbal
 assembly 84 secured to cartridge 82, which in turn is secured to plate
 component 80B. In the illustrated embodiment, plate component 80B is
 oriented to offset cartridge 82 and head-gimbal assembly 84 to one side of
 and above the main portion of plate component 80A. When the cartridge is
 secured to plate component 80B, as shown in FIG. 7, the resilient
 elongated suspension member 84A of the secured head-gimbal assembly 84
 extends principally in the direction of the X-axis, but also is angled
 downward. An actuator plate component 80C extends from component plate 80A
 in the direction of the Z-axis. Plate component 80C supports two actuators
 88 and 96 which comprise portions of two head control mechanisms described
 below. Those head control mechanisms are adapted to engage the suspension
 member 84A of the head and gimbal assembly 84 to position a slider 110 in
 the Z axis direction relative to a magnetic disk (not shown).
 The first head control mechanism includes an elongated protector bar 86
 extending in the Y direction, for engaging the underside of suspension
 member 84A between slider 110 and cartridge 82, but proximate to slider
 110. Protector bar 86 is movable in the Y-axis direction, and oriented
 orthogonally to the principal axis of suspension member 84A. A first rail
 90 is integral with plate component 80A and oriented in the Y-axis
 direction. Protector bar 86 is secured to a first carriage 106, which is
 slidably coupled to rail 90. A first actuator 88 drives carriage 106 and
 bar 86 via drive shaft 88A which extends through an opening formed in
 actuator plate component 80C and, accordingly, causes movement of
 protector bar 86 in the Y-axis direction. The top surface 86A of the
 distal end of protector 86 is a predetermined distance, D1, from the
 cartridge support surface 80B of head loading mechanism 85. That distance
 D1 is sufficient to ensure that the suspension member 84A is deflected
 upward (from its nominally downward inclination) when the cartridge 82 is
 mounted to the support surface of plate 80B when the protector bar 86
 extends through the suspension plane. In the preferred form, protector bar
 86 is made from a plastic material with a low coefficient of friction,
 e.g. Delrin-AF, such that the bar 86 can not damage the electrical wires
 (not shown) at the underside of suspension member 84A. As will be
 appreciated by those skilled in the art, protector bar 86 serves a
 protection function similar to that of a typical plastic "comb" used for
 separating the heads of a head stack.
 The second head control mechanism includes an elongated lift arm 100 for
 engaging lifting tab 84B of suspension member 84. Lift arm 100 is movable
 along two orthogonal axes. By way of example, the arm may be metal but
 relatively thin, for example, having a thickness of 0.004 inches. The
 second head control mechanism includes a second rail 92 integral with
 plate 80A and disposed in the Y-axis direction parallel to the first rail
 90. A second carriage 94 is slidably coupled to rail 92 and moves in the
 Y-axis direction. A second actuator 96 drives the second carriage 94 back
 and forth on rail 92 via a second shaft 96A which extends parallel to the
 Y-axis through an opening formed in actuator plate 80C. The Y-direction
 range of motion of lift arm 100 (due to motion of carriage 94 on rail 82)
 permits lift arm 100 to be extended through the suspension plane in an
 "extended" position, and to be outside the suspension plane in a
 "retracted" position.
 Carriage 94 also includes a first extension 94A, vertical to the Y-axis and
 in the direction of a Z-axis, from which there is a second extension 94B
 that overhangs rail 92 in the direction of the Y-axis. First extension 94A
 includes a third rail 98 extending in the Z-axis direction. A third
 carriage 94C is slidably coupled to rail 98. Carriage 94C supports lift
 arm 100 so that lift arm 100 extends in the direction of the Y-axis. A
 third actuator 102 drives carriage 94C via a third shaft 102A, which
 extends through an opening in second extension 94B. Actuator 102 causes
 controllable displacement of lift arm 100 (and its supporting carriage
 94C) in the Z-axis direction. The Z-direction range of motion of lift arm
 100 (due to motion imparted by actuator 102) permits lift arm 100 to move
 from points above the top surface 86A of protector bar 86 to points below
 the suspension member 84A when the cartridge 82 is mounted to the support
 surface of plate 80B.
 For the embodiment of FIG. 7, FIGS. 8A-8H shown schematic cross sectional
 views in the suspension plane of portions of head-loading mechanism 85 and
 head-gimbal assembly 84 in a series of eight steps which comprise a
 head-loading operation. Before testing a head or disk on a magnetic head
 and disk tester, the slider 110 of head-gimbal assembly 84 must be "loaded
 on" a magnetic disk 104, i.e., positioned at a "flying height" distance
 from the disk which supports the reading and writing of data. In FIGS.
 8A-8H, only the protector bar 86, suspension member 84A, lift tab 84B,
 mounting portion 84C, lift arm 100, disk 104, slider 110 and support plate
 80B are shown.
 Initially, the lift arm 100 is in its retracted position. Step 1, FIG. 8A,
 depicts the start of the loading operation, wherein a head cartridge 82
 and 84 (including cartridge/head-gimbal assembly 82/84(elements 84A, 84B,
 84C and 110) is moved (e.g. an operator) toward and installed onto support
 plate 80B of the head loader 85. During this step, protector bar 86 is in
 an extended position such that bar 86 underlies the anticipated placement
 location for suspension member 84A of head gimbal assembly 84. During this
 installation of the cartridge 82, the top surface 86A of protector bar 86
 interferes with the suspension member 84A causing it to resiliently
 deflect upward (relative to mounting portion 84C) as cartridge 82
 approaches plate component 80B. Step 2, FIG. 8B and FIG. 9, shows the
 position of protector bar 86 and suspension member 84A after cartridge 82
 is installed onto base plate component 80B. Since protector bar 86 is
 manufactured out of a plastic material with low coefficient of friction,
 any electrical wires underneath the suspension will not be damaged during
 this installation operation. Moreover, as shown in FIG. 8B, protector bar
 86 establishes a position of lift tab 84B at a distance D2 from the plane
 P. The distance D2 is selected for the particular geometry of the
 cartridge 82 and attached head-gimbal assembly 84 to ensure that the
 slider 110 cannot physically contact disk 104, and also to ensure that the
 lift arm 100 can reliably engage lift tab 84B.
 In steps, as shown in FIG. 8C and FIG. 10, after the cartridge 82 and
 attached head-gimbal assembly 84 are is installed on base plate 80B,
 actuator 96 extends lift arm 100 in the Y-axis direction to underlie tab
 84B of head-gimbal assembly 84. In step 4, FIG. 8D, actuator 102 drives
 lift bar 100 to engage tab 84B and lift the head-gimbal assembly 84 off of
 protector bar 86. While in this embodiment, the lift arm 86 engages the
 suspension member 84A at lift tab 84B, in other embodiments (e.g., without
 such a lift tab), arm 100 may engage suspension member 84A at another
 point close to slider 110. Next, in Step 5, FIG. 8E and FIG. 11, actuator
 88 retracts protector bar 86. In Step 6, FIG. 8F and FIG. 12, the
 head-loading mechanism 85 (by portions of the spinstand which are not
 shown) is positioned over disk 104. In step 7, FIG. 8G, lift arm 100 is
 lowered (by actuator 102) until lift arm 100 disengages with tab 84B of
 the suspension member 84A and until the slide 110 reaches a position that
 the slider 10 together with its read and write elements "fly" over disk
 104. At this time, a gap exists between disk 104 and lift arm 100.
 Actuator 96 then retracts lift arm 100 as shown in Step 8, FIG. 8H and
 FIG. 13, which completes the loading operation. Accordingly, head-gimbal
 assembly 84 is ready for testing. Although FIGS. 8G and 8H appear to show
 slider 110 in actual contact with disk 104, it will be understood that
 slider 110 is separated from disk 104 by the flying height, a very small
 physical distance.
 Once testing is complete, head-gimbal assembly 84 can be unloaded from the
 disk. During the unloading operation, Steps 1-8 of FIGS. 8A-8H outlined
 above for the loading operation, are performed in reverse order. That is,
 actuator 96 first extends lift arm 100 such that it is disposed between
 disk 104 and the suspension member of head-gimbal assembly 84, but is in
 contact with neither. Actuator 102 then lifts lift arm 100 which in turn
 lifts head-gimbal assembly 84 away from disk 104. Next, the head-loading
 mechanism is positioned such that head-gimbal assembly 84 is outside the
 disk area and actuator 88 extends protector bar 86 such that it is under
 the suspension member 84A of head-gimbal assembly 84. Actuator 102 then
 lowers lift arm 100 which in turn lowers head-gimbal assembly 84 onto
 protector bar 86. Finally, actuator 96 retracts lift arm 100, which
 completes the unloading operation. Cartridge 82 and head-gimbal assembly
 84 can then be replaced, if desired, with a different cartridge and
 head-gimbal assembly or disk 104 can be replaced, if desired. In either
 case, the same loading, testing and unloading sequence can be commenced.
 Although the invention has been shown and described with reference to a
 specific preferred embodiment, it should be understood that the
 description of the preferred embodiment does not limit the field of
 application of the invention and that many modifications are possible
 within the limits of the appended claims. For example, lift arm 100 may
 contact the suspension member 84A of the head-gimbal assembly 84 at a
 different point, rather than at a lift tab at the end of the suspension
 member. In some cases, for instance, suspension member 84A may not include
 a lifting tab. Or, the lift arm 100 may have a wedge shaped end for
 engaging suspension member 84, instead of the squared off end described
 above. In this configuration, the vertical actuator for the lift arm 100
 is not necessary. The inclined surface of the wedge effects the vertical
 motion necessary for loading and unloading. As another example, a
 different number or combination of actuators may be used for driving the
 protector and lift arms. In addition, different configurations for the
 head cartridge can be used, for example without discrete cartridge 82.
 Accordingly, the invention may be embodied in other specific forms without
 departing from the spirit or central characteristics thereof. The present
 embodiments are, therefore, to be considered in all respects as
 illustrative and not restrictive, the scope of the invention being
 indicated by the appending claims rather than by the foregoing
 description, and all changes that come within the meaning and range of
 equivalency of the claims are therefore intended to be embraced therein.