KR19990067213A - Disc drive spindle motors with hydraulic bearings with optimized lubricant with additive compatible with disc drives - Google Patents

Abstract

The disc drive 10 includes a housing 12, a central axis 80, a fixing member 34 fixed to the housing and coaxial with the central axis, and rotatable about the central axis with respect to the fixing member. Possible member 36 is included. Stator 38 is fixed relative to the housing. The rotor 70 is supported by the rotatable member and magnetically coupled to the stator. At least one data storage disk 16 is attached to and is coaxial with the rotatable member. A hydraulic bearing 37 interconnects the stationary member with the rotatable member and has a basic fluid 84, an antioxidant additive, an anticorrosion additive and a viscosity of at least 110 which is effective to suppress catalyst degradation in the hydraulic bearing. Hybrids of antiwear additives.

Description

Disc drive spindle motor with hydraulic bearing with optimized lubricant with additive compatible with disc drive

Disc drive data storage devices known as "Winchester" type disc drives are well known in the art. In a Winchester disc drive, the digital data is written to and read from the thin layer of magnetizable material on the surface of the rotating disk. Write and read operations are performed via a transducer carried to the slider body. These sliders and transducers are sometimes referred to collectively as heads, and typically one head is associated with each disk surface. The head is moved by the actuator device to one track of a plurality of concentric data tracks which are circular on the disk surface under the control of the electronic circuit. Each slider body includes a self-acting air bearing surface. As the disc rotates, it pulls air below the air bearing surface, which creates a lifting force that lifts the slider so that the slider glides over several microinches of the disc surface. .

The most commonly used type of actuator in disc drive devices currently being produced is a rotary moving coil actuator. The disc itself is typically mounted "stack" on the hub structure of a brushless DC spindle motor. The rotational speed of the spindle motor is precisely controlled by the motor drive circuit which controls the timing and power of the communication signal directed to the stator winding of the motor. A typical spindle motor has a speed of 3600 rpm. Current technology can increase spindle motor rotational speeds to 7200 rpm, 10,000 rpm and beyond.

A major source of noise in disk drive data storage devices is the spindle motor. Disc drive manufacturers have recently replaced conventional ball or roller bearings in spindle motors with "hydro" bearings, such as hydrodynamic bearings or hydrostatic bearings. We are looking for Hydrodynamic bearings are self-pumping bearings that generate pressure internally to maintain oil film separation. Hydrostatic bearings require an external pressurized fluid source to maintain fluid separation. The relative movement between the bearing surfaces in the hydraulic bearings prevents the shearing elements which occur entirely in the oil film from contacting the bearing surfaces.

This phenomenon can be caused by conventional boundary lubrication applications, such as roller bearings, ball bearings, and sliding bearings, where the solid bearing surfaces often come into contact with each other and generate shear stresses at their interfaces, or by elastohydrodynamic lubrication. application). In such boundary applications, the primary use of lubricants is to modify the interface to reduce wear and friction. The interfacial chemistry of the lubricant is the most important factor.

In hydraulic bearing applications, overall different fluid properties are important factors for the function of the bearing. The boundary property is an important factor only while starting and stopping disk rotation. During normal operation, bulk properties are the most important factor. Hydraulic bearings contemplated for use in disk drive devices are compact devices that do not leak from the bearings and require limited oil supply and small power dissipation that must be suitable for the long life of the bearings. Commercially available lubricants are inadequate for most small hydraulic bearings in disc drives.

The lubrication properties to be controlled and the degree of control to be achieved differ for each small hydraulic bearing for a disc drive. These properties include power dissipation, viscosity and temperature dependence of this viscosity, migration, vapor pressure and evaporation rate, resistance to oxidation and corrosion, fluidity, boundary properties, and system compatibility. Viscosity determines power dissipation and bearing stiffness that must be very constant over several operating conditions. The lubricant must have a low migration so that it does not leak out of the bearings. Lubricants must have high resistance to oxidation and reactivity to extend bearing life. Fluidity is the deformation and flow response to shear.

The lubricant must be compatible with other materials of the disc drive. For example, the migration or leakage of lubricant should not damage the interface between the head and the disk due to factors such as increased adhesive friction between the head and the disk or deterioration of the head structure or head operation. The formation of suitable fluids for hydraulic bearings requires different considerations than the fluids to be used as lubricants for general use. Another disadvantage of commercially available lubricants is that the exact composition of the lubricant will not be provided by the manufacturer and must include one or more additives that are incompatible with the sensitive operation of the disk drive.

FIELD OF THE INVENTION The present invention relates to spindle motors for disk drive data storage devices and, in particular, to optimized lubricants for hydrodynamic bearings in spindle motors.

1 is a plan view of a disk drive data storage device according to the present invention.

2 is a sectional view of a hydrodynamic spindle motor according to the present invention.

FIG. 3 is a cross sectional view of the hydrodynamic spindle motor with portions omitted for clarity and clarity along line 3-3 of FIG.

The disk drive data storage device of the present invention includes a housing, a central axis, a fixing member fixed to and coaxial with the housing, and a rotatable member rotatable about a central axis with respect to the fixing member. The stator is fixed with respect to the housing. The rotor is supported by the rotatable member and magnetically connected to the stator. At least one data storage disk is attached to and coaxial with the rotatable member. The hydraulic bearings are interconnected with the stationary and rotatable members and comprise a mixture of base fluids, antioxidant additives, anticorrosion additives and antiwear additives having a viscosity of at least 110, which additives are in contact with the hydraulic bearings. It is effective in suppressing catalytic degradation.

In a preferred embodiment, the blend is an antioxidant additive having a concentration of 0.25 to 3% by weight, an anticorrosive additive having a concentration of 0.05 to 0.5% by weight, and an antiwear additive having a concentration of 0.1 to 4% by weight. Have Basic fluids are preferably esters, synthetic hydrocarbons, hybrids of different esters or mixtures of different synthetic hydrocarbons. The antioxidant additive is preferably selected from the group consisting of amines and phenols. The anticorrosion additive is preferably selected from the group consisting of metallic sulfonates, long chain amines, carboxylic acid derivatives, thiadiazole derivatives, triazole derivatives, and amine phosphates. The antiwear additive is selected from the group consisting of dialkyl dithiophosphates, alkyl disulfides, alkyl polysulfides, aryl disulfides, aryl polysulfides, dithiocarbamates, salts of alkyl phosphates, moldibdenum complexes, and neutral phosphate esters. It is preferable.

The disk drive data storage system further includes an actuator and a head supported by an actuator adjacent to the data storage disk for communicating with the disk. Preferred components of the lubricant are compatible with the interface between the head and the disk. For example, these components should not significantly increase the cohesive friction between the head and the disk caused by the leakage of these components in the bearing. In addition, these components should not cause degradation of the structure or operation of the head and disk.

According to the present invention, a disk drive data storage device is provided that includes a hydrodynamic or hydrostatic bearing spindle motor having a lubricating oil composition optimized for the unique requirements of the disk drive. 1 is a plan view of a conventional disk drive 10 to which the present invention can be applied. The disc drive 10 includes a housing base 12 and a top cover 14. The housing base 12 engages with the top cover 14 to form a sealed environment so that internal components can be protected from contamination by elements outside of this sealing environment.

The disk drive 10 further includes a disk pack 16 mounted on a spindle motor (not shown) by the disk clamp 18 for rotation. The disc pack 16 includes a plurality of individual discs mounted for co-rotation about the central axis. Each disk surface has an associated head 20 mounted to the disk drive 10 for communicating with the disk surface. In the example shown in FIG. 1, the head 20 is supported by the flexure 22 and attached to the head mounting arm 24 of the actuator body 26. The actuator shown in FIG. 1 is of a type known as a rotary moving coil actuator and includes a voice coil motor (VCM), indicated at 28. The voice coil motor 28 rotates the actuator body 26 and the head 20 attached to the actuator body about the pivot shaft 30 to position the head 20 on the required data track along the arcuate path. Let's do it. Although a rotary actuator is shown in FIG. 1, the present invention is also useful for disc drives having other types of actuators, such as linear actuators.

2 is a cross-sectional view of a hydrodynamic bearing spindle motor 32 in accordance with the present invention. The spindle motor 32 includes a stationary member 34, a hub 36 and a stator 38. In the embodiment shown in FIG. 2, the fastening member is a shaft fixed and attached to the base 12 via a nut 40 and washer 42. The hub 36 is interconnected with the shaft 34 via a hydrodynamic bearing 37 for rotation about the shaft 34. The bearing 37 comprises radial working surfaces 44 and 46 and axial working surfaces 48 and 50. Shaft 34 includes fluid ports 54, 56, 58 that supply lubricating oil 60 and help circulate fluid along the working surface of the bearing. Lubricant 60 is supplied to shaft 34 by a fluid source (not shown) that is connected to the interior of shaft 34 in a known manner.

The spindle motor 32 further comprises a screw bearing 45 forming a coaxial working surface 48, 50 of the hydrodynamic bearing 37. The counterplate 62 is against the working surface 48 to provide axial stability to the hydrodynamic bearing and to position the hub 36 on the spindle motor 32. O-ring 64 is installed between counterplate 62 and hub 36 to seal the hydrodynamic bearing. This sealing prevents the hydrodynamic fluid 60 from leaking between the counterplate 62 and the hub 36.

The hub 36 includes a disk carrier member 66 and a central core 65 that support the disk pack 16 (see FIG. 1) for rotation about the shaft 34. The disc pack 16 is fixed on the disc carrier member 66 by the disc clamp 18 (see FIG. 1). A permanent magnet 70, which acts as a stator for the spindle motor 32, is attached to the outer diameter of the hub 36. The core 65 is made of magnetic material and acts as a back-iron for the magnet 70. The rotor magnet 70 may be configured as a monolithic annular ring or may be composed of a plurality of individual magnets spaced apart about the circumference of the hub 36. Rotor magnet 70 is magnetized to form one or more magnetic poles.

Stator 38 is attached to base 12 and includes a stator stack 72 and stator windings 74. Stator winding 74 is attached to stack 74. The stator winding 74 is radially spaced from the rotor magnet 70 so that the rotor magnet 70 and the hub 36 can rotate about the central axis 80. The stator 38 is attached to the base 12 via a known method, such as one or more C-clamps 76 secured to the base via bolts 78.

The communication pulse applied to the stator winding 74 creates a rotating magnetic field that communicates with the stator magnet 70 and allows the hub 36 to rotate about the central axis 80 on the bearing 37. The communication pulse is a timed polarization-selected DC current pulse directed to a stator winding sequentially selected to drive the rotor magnet and control its speed.

In the embodiment shown in FIG. 2, the spindle motor 32 is a "below-hub type motor" having an axial position in which the stator 38 is below the hub 36. The stator 38 also has an axial position outside the hub 36 such that the stator winding 74 is secured to the inner diameter surface 82 of the stack 72. In other embodiments, the stator may have a radial position inside or outside the hub. Further, the spindle motor may have a fixed shaft or a rotating shaft as shown in FIG. In a rotary shaft spindle motor, the bearing is located between the rotary shaft and an outer stationary sleeve coaxial with the rotary shaft.

3 is a cross-sectional view of the hydrodynamic spindle motor 32 cut along line 3-3 of FIG. 2 and partially omitted for clarity of illustration. The stator 38 includes a stack 72 and a stator winding 74 coaxial with the rotor magnet 70 and the central core 65. Stator winding 74 includes phase windings W1, V1, U1, W2, V2, and U2 wound around teeth in the stack 72. The phase winding consists of a coil having a coil axis perpendicular to the center axis 80 and intersecting this center axis. For example, the phase winding W1 has a coil axis 83 perpendicular to the central axis 80. The radial working surfaces 44, 46 of the hydrodynamic bearing 37 are formed by the outer diameter surface of the shaft 34 and the inner diameter surface of the central core 65. Radial working surfaces 44 and 46 are separated by lubricating oil 84 to maintain the spacing c during normal operation.

1. Optimization of lubricant viscosity

In accordance with one aspect of the present invention, the lubricant may be used to precisely determine fluid viscosity to optimize power dissipation and bearing load performance (ie, bearing stiffness) for the particular hydrodynamic bearing design in which the fluid is used. Contains hybrids.

Power consumption P and bearing stiffness K are proportional to fluid viscosity according to the following relationship.

Where μ _B is the absolute viscosity of the hybrid of the fluid, ω is the relative viscosity of the hub, c is the gap or gap between the radial working surfaces 44,46 (or the axial working surfaces 48,50). , R is the characteristic length of the radial work surface and / or the axial work surface.

In disc drive devices with compact hydrodynamic bearings, power and load performance are important factors. Therefore, it is desirable to specify the correct viscosity at any particular temperature for the lubricating oil, and the required viscosity varies with the size and structure of the spindle motor. Commercial lubricants cannot be used with any viscosity value. Lubricants of the present invention include hybrids of base fluids in which each base fluid has a similar chemical composition but different viscosity. The base fluid is precisely blended to obtain an overall viscosity that is preferably within 10% and most preferably within 2-5% of the required viscosity. The base fluid is hybridized according to the following relationship.

μ _{B acT-TC} = ν ₁ × ρ ₁ × χ ₁ + ν ₂ × ρ ₂ × χ ₂ + ⃛ + ν _n × ρ _n × χ _n

Where μ _B is the absolute viscosity of the hybrid of the base fluid at temperature T _C , T _C is the temperature at which viscosity is required, ν _n is the kinematic viscosity of base fluid n, n is an integer greater than 1, ρ _n Is the density of base fluid n, χ _n is the weight percentage ratio of base fluid n, and χ ₁ + χ ₂ +. + χ _n = 1.

For example, n = 2, and if the mixed water, the required movement viscosity is ν, ν _1> ν> so that the ν ₂ appropriately select ν ₁ ν ₂ and it is possible to obtain a lubricating oil of the desired viscosity.

Preferred base fluids include perfluoropolyethers, esters, synthetic hydrocarbons and highly purified mineral hydrocarbons. Most preferred base fluids include diesters, polyol esters and polyalphaolefins (PAO). These base fluids may be mixed in various combinations, but preferred hybrids include combinations of esters only, combinations of polyalphaolefins only, and combinations of at least one ester and at least one polyalphaolefin only. If the fluid has the required viscosity and meets other desired properties, a single ester or polyalphaolefin may be used in other embodiments of the present invention.

This most preferred base fluid has been found to provide several advantages for disk drive devices over conventional petroleum-based hydrocarbons present in standard fluid lubricants. These base fluids have low viscosity dependence on temperature, low evaporation, low vapor pressure, low migration, improved oxidation resistance, similar boundary performance that can be easily improved with additives, good compatibility with other materials in the disc drive, and known It has good control of all properties due to its pure chemical composition. Thus, these fluids minimize degradation of the interface between the head and the disk and provide long life to the bearing and the disk drive.

In a preferred embodiment, the base fluid has a precise absolute viscosity of 4-10 centipoise (cP) at a temperature of about 70 ° C., a viscosity of at least 110, based on a volume to surface area (V / A) ratio of about 1.9 to 2.0 mm. Hybridization to obtain a rate and an evaporation range of less than 1.0 × 10 ⁻³ mg / day-mm ² .

The base fluid is also used in disc drives under various conditions, such as high temperature or high humidity, where the base fluid's contribution to cohesive friction ("stick") between the head and the disc due to fluid leakage from the bearings to the disc. It is chosen to be similar to or less than the contribution of existing chemicals or lubricants. These chemicals and lubricants include, for example, greases and ferrofluidic seals.

2. Hybrid of lubricant and selected additives

In another aspect of the invention, the lubricant is an additive selected such that the high viscosity base fluid (or hybrid of the base fluid) and the mixture are compatible with the head-disk interface while being effective in preventing contact degradation. And mixtures thereof.

The viscosity of the lubricant in hydrodynamic bearings drops with increasing temperature. This drop in viscosity lowers power dissipation and bearing load capacity for fluids having a certain thickness. In disc drive devices with small hydrodynamic bearings, large variations in power dissipation and bearing load capacity are unacceptable.

Viscosity (VI) is an arbitrary way of expressing the viscosity-temperature sensitivity of lubricating oil and is often interpreted as the temperature dependence of viscosity. Higher viscosity for fluids with a certain viscosity indicates that the viscosity of the fluid changes less with temperature. Since power dissipation is an important parameter for hydrodynamic bearings in small disk drives, high viscosity is required. Typical viscosities for various classes are shown in Table 1 below.

Chemical class of fluid VI range available Refined Paraffin Mineral 90-110 Synthetic Hydrocarbons (Polyalphaolefins) 120 to 170 Synthetic ester (diester) 120 to 200 Synthetic esters (polyols) 115-200 Perfluoropolyether 90 to 320

Ester fluids include hydrogen and carbon as well as oxygen, and some ester fluids offer inherent advantages to disk drive devices across natural and synthetic hydrocarbon fluids. These advantages include higher viscosity, higher oxidation resistance, improved boundary lubrication properties, lower migration and lower evaporation compared to synthetic hydrocarbons.

For example, commercially available diester fluids have high viscosity and good oxidation resistance but poor resistance to contact loss upon metal-to-metal contact. For this reason, the oil's volume is so small that even minor breakdowns make it impossible to use commercially available diester fluids in small hydrodynamic bearings that adversely affect bearing properties.

Commercially available fluids do not contain suitable metal inert additives to extend the life of the bearings. In addition, most commercially available fluids have components that are incompatible with the head-disk interface. Sometimes the exact composition of commercially available fluids is not controlled by the manufacturer. Thus, the use of such fluids can lead to unexpected degradation of disk drive performance.

Lubricants of the present invention are blends of high viscosity base fluids, such as diester fluids or polyalphaolefins, and commercially available ester and / or synthetic hydrocarbon blends, while the fluids are compatible with the head-disk interface. And compositions of additives selected to provide this fluid with anti-oxidation, anti-corrosion and metal deactivation properties to have better resistance to contact loss.

Preferred types of antioxidants include inhibitors comprising nitrogen and corals such as amines (arylamines), phenols or mixtures thereof. Most preferred types of antioxidants include butanolated hydroxytoluene (liquid minor free phenol), alkylated diphenyl amines, phenyl alpha naphthylamine or two or more compositions of these antioxidants. Preferred treatment levels for these additives in the lubricating base fluid are 0.25-3% by mass.

Preferred types of rust and corrosion inhibitors or metal passivators include metallic sulfonates, long chain amines, carboxylic acid derivatives, triadiazole derivatives, triazole derivatives, and amine phosphates. Most preferred types of rust and oxidation inhibitors or metal antifreeze agents are synthetic or mineral calcium sulfonates, synthetic or mineral barium sulfonates, alkenyl succinic acid derivatives and triazole derivatives. Preferred treatment levels of these additives in the lubricating base fluid are from 0.02 to 0.5 mass%.

The lubricating oil of the present invention further includes additives for improving antiwear properties, high pressure metal contact properties, and friction properties. Preferred additives of this type include neutral phosphate esters such as dialkyl dithiophosphates, alkyl disulfides, alkyl polysulfides, aryl disulfides, aryl polysulfides, dithiocarbamates, salts of alkyl phosphates, molybdenum complexes, triphenyl phosphates ( Triaryl and trialkyl), or one or more compositions of these additives. Most preferred antioxidant additives are zinc dialkyl dithiophosphates, molybdenum disulfides, liquid amine phosphates, propylated triphenyl phosphates, and butanated triphenyl phosphates. The preferred treatment level of these additives in the lubricating base fluid is 4 mass%.

Selecting these additives to blend high viscosity diester-based oils and / or synthetic hydrocarbons results in hydrodynamic fluids with greater resistance to contact degradation than commercially available ester or synthetic hydrocarbon blends. You can get it. Testing various hybrids shows that they are compatible with the head-disk interface. These hybrids do not result in a significant increase in cohesive friction between the head and the disk and do not cause other interference with the head-disk interface. Hybrids have also been found to be superior to purified paraffinic mineral fluids in terms of lifetime and power consumption under excessive loads and elevated temperatures.

3. Application of high shear strength viscosity improving fluid

In another aspect of the invention, the lubricating oil comprises a mixture of a base fluid and a shear-resistant viscosity modifier ("viscosity enhancer"). Viscosity enhancers reduce the temperature dependence of the viscosity of the base fluid. The temperature dependence of viscosity is a very important factor, and high temperature dependence is not always desirable for the function of small bearings on spindle motors. To minimize this effect, selected commercially available polymers are blended with the base fluid according to the invention to improve the temperature-power consumption curve measured at the spindle motor. The dependence of power consumption on temperature has been observed to decrease.

In a preferred embodiment of the present invention, a high molecular weight soluble polymer is added to the base fluid at 5-50% by weight, provided another suitable base fluid with improper temperature-viscosity operation is provided. The molecular weight of this polymer is preferably 10,000 to 1,000,000 daltons. Preferred polymer viscosity modifiers include polyacrylates, polyisoprene and polystyrene, but are not necessarily limited to these materials.

Under the conditions encountered with the compact hydrodynamic bearings according to the invention, the shear rate is at least 10 ⁶ per second. The shear rate is defined as the rate of change of viscosity of the bearing working surface over the width of the gap (gap c shown in FIG. 3) in the bearing. The shear state between the bearing surfaces limits the lifetime of the viscosity modifier by breaking down the polymer. Since the effect of viscosity is dependent on the length of the polymer chain, among other factors, the effectiveness of the viscosity enhancer is reduced by shear breakdown.

In a more preferred embodiment of the invention, the selected polymer viscosity modifiers belong to the class of polymers in which the elongation strength of the solid polymer is at least 10,000 psi and resistant to thermal degradation of at least 250 ° F. and has high resistance to shear breakdown. . Therefore, the polymer has shear strength. Polymers of this class include, but are not necessarily limited to, soluble forms of materials such as polyphenylene sulfide, polyetheretherketone and polyetherimide.

In a more preferred embodiment of the invention, the solid polymer has an elongation strength of at least 14,000 psi and resistance to thermal degradation of at least 500 ° F. Polymers of this class include, but are not necessarily limited to, polyamide-imides, polyimides, polybenzimidazoles, and liquid crystalline polymers. In a more preferred embodiment, the solid polymer has a stretch strength of at least 20,000 psi and resistance to thermal degradation of at least 700 ° F. This class of polymers includes, but is not necessarily limited to, buckytube and other buckminsterfullerene carbon forms.

In the most preferred embodiment, the polymer viscosity modifier has the properties of the previous group and is functionalized or chemically modified to provide antioxidant and metal deactivation protection to the fluid as described above.

Although the present invention has been described with reference to preferred embodiments, those skilled in the art will be able to make changes in form and detail without departing from the spirit of the invention.

Claims (21)

A disk drive data storage device, A housing; A central axis; A fixing member fixed to the housing and coaxial with the central axis; A stator fixed relative to the housing; A rotatable member rotatable about the central axis relative to the stationary member; A rotor supported by the rotatable member and magnetically coupled to the stator; At least one data storage disk attached to the rotatable member and coaxial with the rotatable member; An actuator supporting a head proximate the data storage disk for communicating with the disk; Interconnecting the stationary member with the rotatable member and having a base fluid having a viscosity of at least 110 with an antioxidant additive, anticorrosion additive and antiwear additive having the effect of inhibiting contact loss in a hydraulic bearing. And a hydraulic bearing having lubricating oil comprising a hybrid. The disk drive data storage device of claim 1, wherein the antioxidant additive has a concentration of 0.25 to 3% by weight in the hybrid. The disk drive data storage device of claim 1, wherein the anti-corrosion additive has a concentration of 0.02 to 0.5% by weight in the hybrid. The disk drive data storage device of claim 1, wherein the antiwear additive has a concentration of 0.1 to 4% by weight in the hybrid. The disk drive data storage device of claim 1, wherein the antioxidant additive is selected from a group consisting of an oxidation inhibitor including nitrogen and oxygen. 6. The disk drive data storage device of claim 5, wherein the antioxidant additive is selected from the group consisting of amines and phenols. 6. The disk drive data storage device of claim 5, wherein the antioxidant additive is comprised of a mixture of amines and phenols. The disk drive data storage device of claim 1, wherein the antioxidant additive is selected from the group consisting of butanated hydrotoluene, alkylated diphenyl amine, and phenyl alpha naphthylamine. The method of claim 1, wherein the antioxidant additive is characterized in that it is composed of a mixture of at least two additives selected from the group consisting of butanated hydrotoluene, alkylated diphenyl amine and phenyl alpha naphthylamine. Disk drive data storage. The disk drive data of claim 1, wherein the anti-corrosion additive is selected from the group consisting of metallic sulfonates, long chain amines, carboxylic acid derivatives, thiadiazole derivatives, triazole derivatives, and amine phosphates. Storage device. The method of claim 10, wherein the anti-corrosion additive is selected from the group consisting of synthetic calcium sulfonate, mineral calcium sulfonate, synthetic barium sulfonate, mineral barium sulfonate, alkenyl succinic acid derivatives and triazole derivatives. Disk drive data storage device. The antiwear additive according to claim 1, wherein the antiwear additive is a dialkyl dithiophosphate, alkyl disulfide, alkyl polysulfide, aryl disulfide, aryl polysulfide, dithiocarbamate, salt of alkylphosphoric acid, molybdenum complex, and neutral phosphate ester Disk drive data storage device, characterized in that selected from the group consisting of. The disk drive data storage device of claim 1, wherein the antiwear additive is selected from the group consisting of triaryl phosphate and trialkyl phosphate. The antiwear additive according to claim 1, wherein the antiwear additive is a dialkyl dithiophosphate, alkyl disulfide, alkyl polysulfide, aryl disulfide, aryl polysulfide, dithiocarbamate, salt of alkylphosphoric acid, molybdenum complex, and neutral phosphate ester A disk drive data storage device comprising at least two additives selected from the group consisting of. The antiwear additive according to claim 1, wherein the antiwear additive is selected from the group consisting of zinc dialkyl dithiophosphate, molybdenum disulfide, liquid amine phosphate, propylated triphenyl phosphate, and butanated triphenyl phosphate. Disk drive data storage. The disk drive data storage device of claim 1, wherein the base fluid is selected from the group consisting of diesters, polyol esters, polyalphaolefins, perfluoropolyethers, and mineral hydrocarbons. 17. The disk drive data storage device of claim 16, wherein the base fluid is selected from the group consisting of diesters and polyol esters. The method of claim 1 wherein the base fluid comprises a hybrid of at least two base fluids selected from the group consisting of diesters, polyol esters and polyalphaolefins, wherein each base fluid in the hybrid has a different viscosity Disk drive data storage device characterized in that it has a. 2. The apparatus of claim 1, further comprising an actuator and a head supported by an actuator adjacent to the data storage disk for communicating with the data storage disk, the head and disk having an interface, the hybrid having the interface. Disk drive data storage device, characterized in that consisting of a base fluid, antioxidant additives, anti-corrosion additives and anti-wear additives compatible with the. 2. The disk drive data storage device according to claim 1, wherein said hybrid has an effect of suppressing an increase in adhesive friction between said head and disk caused by leakage of said hybrid from said hydraulic bearing. A hydraulic bearing disc drive lubricant for lubricating hydraulic bearings in a disc drive, A base fluid selected from the group consisting of diesters, polyol esters, polyalphaolefins, perfluoropolyethers and mineral hydrocarbons; Antioxidant additives selected from the group consisting of amines and phenols; Anti-corrosion additives selected from the group consisting of metallic sulfonates, long chain amines, carboxylic acid derivatives, thiadiazole derivatives, triazole derivatives, and amine phosphates; Antialkyl additives selected from the group consisting of dialkyl dithiophosphates, alkyl disulfides, alkyl polysulfides, aryl disulfides, aryl polysulfides, dithiocarbamates, salts of alkylphosphates, molybdenum complexes, and neutral phosphate esters Hydraulic bearing disc drive lubricant, characterized in that.