Suspension Design Suspension Design Progression for Increasing Progression for Increasing
Shock PerformanceShock PerformanceJacob BjorstromJacob Bjorstrom
Sr. Product Design Eng.Sr. Product Design Eng.Hutchinson TechnologyHutchinson Technology
September 22, 2004September 22, 2004
DISKCON 2004
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AgendaAgendaShock TerminologyShock Terminology
A Brief History of Mobile Shock A Brief History of Mobile Shock PerformancePerformance
Suspension/HGA Shock DesignSuspension/HGA Shock Design• Loadbeam, flexure, sliderLoadbeam, flexure, slider
Load/Unload Shock DesignLoad/Unload Shock Design
Drive Design ImpactsDrive Design Impacts
ConclusionsConclusions
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TerminologyTerminologyShock - Shock - a sudden disturbance a sudden disturbance induced on the hard driveinduced on the hard drive
G -G - measure of gravitational measure of gravitational acceleration, the number of G’s is acceleration, the number of G’s is the magnitude of the shock eventthe magnitude of the shock event
Pulse width -Pulse width - length of time that a G length of time that a G load is appliedload is applied
Op-Shock -Op-Shock - a shock event applied a shock event applied while the drive is spinning with the while the drive is spinning with the slider on the diskslider on the disk
Non-op Shock -Non-op Shock - a shock event a shock event where the slider is parked in it’s where the slider is parked in it’s resting position, typically in a mobile resting position, typically in a mobile drive this would be off the disk on drive this would be off the disk on the load/unload ramp.the load/unload ramp.
Gram - Gram - downwarddownward force supplied by force supplied by the suspension to hold the slider on the suspension to hold the slider on the diskthe disk
G/gram -G/gram - suspension parameter suspension parameter used to determine liftoff point of the used to determine liftoff point of the slider from the disk, for a given gram slider from the disk, for a given gram loadload
0
50
100
150
200
250
0 0.0002 0.0004 0.0006 0.0008 0.001 0.0012 0.0014 0.0016 0.0018 0.002
time (sec)
G's
Pulse Width = 1.0ms
Shock Load = 200G
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Mobile TimelineMobile Timeline
3.0” FF
41 G/gram
2.5” FF
61 G/gram
2.5” FF
83 G/gram
1.0” FF
160 G/gram
0.85” FF
707 G/gram
1995 1997 1999 2001 2005
0.85” FF
394 G/gram
2003
17X Improvement in Suspension G/Gram
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History of RequirementsHistory of RequirementsHigh End Mobile Shock Specifications
0
500
1000
1500
2000
2500
1994 1996 1998 2000 2002 2004 2006 2008 2010
Year
G, S
pe
c L
imit micro-HDD non-op shock
micro-HDD op-shock
mobile non-op shock
mobile op-shock
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Four Major Drive Components Four Major Drive Components Affect Shock PerformanceAffect Shock Performance
2. Magnetic Disks
Recording Head
Disk Drive3. Actuator
4. Suspension
Assembly 1. Drive Case
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Achieving Higher ShockAchieving Higher ShockAt the suspension level, the key is to At the suspension level, the key is to reduce the effective load beam massreduce the effective load beam mass
– Mass of the HGA past the bend radiusMass of the HGA past the bend radius
The further the mass is from the bend The further the mass is from the bend radius, the more detrimental it is to shock radius, the more detrimental it is to shock
LOADBEAM SLIDER FLEXUREARM / MOUNT PLATE
BEND RADIUS
EFFECTIVE MASS
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Beam Design and Beam Design and Material ThicknessMaterial Thickness
Thin railed beams have less massive cross-Thin railed beams have less massive cross-sections, which are ideal for shocksections, which are ideal for shock
Thick beam (101 m) cross-section
Thin railed beam (20 m) cross-section
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Mass ReductionMass ReductionBest for shock with acceptable resonance Best for shock with acceptable resonance
Allow for strategic mass reductionAllow for strategic mass reduction
+14% Shock
+5% B1
-5% T1
-9% Sway
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Advanced Concept:Advanced Concept:Laminate BeamsLaminate Beams
Offers resonance Offers resonance improvement over improvement over thin beam designs thin beam designs while keeping high while keeping high shock performanceshock performance
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Effective Beam LengthEffective Beam Length
Effective beam length is the Effective beam length is the distance from the arm / swage plate distance from the arm / swage plate edge to the load pointedge to the load pointA shorter distance reduces A shorter distance reduces suspension mass, and increases suspension mass, and increases shock and resonance performanceshock and resonance performanceTradeoffs are space constraints and Tradeoffs are space constraints and increased risk of gram load lossincreased risk of gram load loss
9.3 mm
4.35 mm
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Flexure Progression: Flexure Progression: Hub Clearance and MassHub Clearance and Mass
Past Present Future
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Slider Size vs. G/GramSlider Size vs. G/GramThe smaller the slider, the higher the G/gram for a given suspensionThe smaller the slider, the higher the G/gram for a given suspensionThe G/gram delta between sliders increases as the slider becomes a The G/gram delta between sliders increases as the slider becomes a larger portion of the effective masslarger portion of the effective mass
Slider Effects on HGA G/gram
0
100
200
300
400
500
600
700
800
0 250 500 750 1000 1250 1500
Suspension Only G/gram (no slider)
HG
A G
/gra
m
2001
2003
2005
300 G/gram
30 G/gram
Pico
Femto
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Slider Size vs. Total G’sSlider Size vs. Total G’sThe smallest head is not necessarily the best for total The smallest head is not necessarily the best for total HGA shock performance when accounting for gram load HGA shock performance when accounting for gram load and slider negative air bearing pressureand slider negative air bearing pressure
Maximum Total HGA Op-Shock by Slider Size
0
500
1000
1500
2000
2500
0 250 500 750 1000 1250 1500
Suspension only G/gram (no slider)
Max
imu
m H
GA
Lif
toff
Val
ue
(G's
)
2001
2003
2005
Pico
Femto
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Shrinking Form FactorShrinking Form FactorAs the drive size decreases, the suspension becomes a As the drive size decreases, the suspension becomes a large factor on drive level shock performancelarge factor on drive level shock performanceSmall form factor drives benefit from both increased Small form factor drives benefit from both increased suspension level G/gram and improved drive dynamicssuspension level G/gram and improved drive dynamics
Suspension's % Contribution to Total Drive Op-Shock SpecDrive Size vs. Suspension % Contribution
0%
20%
40%
60%
80%
100%
120%
0.511.522.533.5
Drive Form Factor (inches)
Su
spen
sio
n's
% C
on
trib
uti
on
to
Dri
ve
Op
-Sh
ock
Sp
ec
.85" Expected Range
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Non-op ShockNon-op ShockShock failure is caused by a large deflection of the head and gimbal during shock. Parameters that affect shock performance are:
1. Ramp design
2. Limiter design
3. Gimbal design
SuspensionGimbal & Slider
Arm
Disk
Ramp Headlift
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Motion Control: Motion Control: LimitersLimiters
No limiters engaged(large deflection of slider and gimbal)
Ramp and T-bar limiters engaged(slider and flexure motion restrained)
Slider
Suspension
Ramp
Slider
SuspensionRamp
Limiters
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HeadliftsHeadliftsParking the slider off the disk Parking the slider off the disk prevents shock damageprevents shock damageMass reduction at the tip of the Mass reduction at the tip of the suspension provides the best suspension provides the best results for increased G/gram liftoffresults for increased G/gram liftoffNew headlift concepts offer twice New headlift concepts offer twice the stiffness and half the massthe stiffness and half the mass
Actual SEM
Standard Offset Form Headlift
New Continuous Rail Form Headlift
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ResultsResults
Large displacement and probable
disk/head damage
Mainstream micro-HDD suspension
HTI leading edge micro-HDD suspension
Shocked at: 1000 G’s 1 ms pulse
No separation between disk and slider
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Systems ViewSystems View
While the suspension is a large factor in drive shock performance, all components in the system must work together for optimal performanceThe same suspension can have different shock performance in different drive designs
Desktop Program #1300G @ 1.0ms
0
0.5
1
1.5
2
2.5
3
3.5
100 125 150 175 200 225 250 275
G/gram
Cu
mm
. Lif
toff
(m
m)
Desktop Program #2300G @ 1.0ms
0
0.5
1
1.5
2
2.5
3
3.5
100 125 150 175 200 225 250 275
G/gram
Cu
mm
. Lif
toff
(m
m)
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ConclusionsConclusions
Shock has become a primary differentiator Shock has become a primary differentiator in mobile drive performance.in mobile drive performance.
New HTI suspension designs continue to New HTI suspension designs continue to expand the current drive level shock expand the current drive level shock performance envelope.performance envelope.
To maximize drive level shock To maximize drive level shock performance, all components must be performance, all components must be designed in harmony with one another.designed in harmony with one another.