Hard Disk

Topics: Hard disk drive, Hard disk platter, Floppy disk Pages: 42 (1184 words) Published: December 24, 2014

•Storage capacity
•Software support

Why we call it as…….
• Hard disk
• Fixed disk
• Winchester disk

Hard Disk Drive Components

Disk platter
Read/Write head
Head arm/Head slider
Head actuator mechanism
Spindle motor
Logic board
Air filter
Cables & Connectors

• Disk platter

• The data’s are stored in this media
• Form factor
9 5.5” - actual size is 5.12”
9 3.5” - actual size is 3.74”

1 1/8”
1 1/3”

• The 5.25” platter were used in earlier days
• Now a days it is replaced by the 3.5”
•The 2.5”,1 1/8”, 1 1/3” & 1” platters are
using in the laptop computers
•Among this the 1” platter are known
as “Microdrive”

• Substrate
¾ The material by which a disk platter is
o Aluminum
o Glass or Glass Ceramic compounds

ƒ To hold the data on the substrate, it
must be coated with magnetic media
o Iron Oxide media
o Thin Film media

¾ Iron Oxide media
9 It gives around 30 meu inch

9 Looks brown or amber in colour
9 Semi liquid coating of the iron oxide

¾ Thin Film media
9 Very thin coating
9 Only 1-4 meu inch thickness
9 It is coated over the substrate by using
two types of process

Plating process

The media is produced by
electroplating process
Substrate is immersed in different

Sputtering process
It provides better thin film coating
This provides thinnest, hardest and
finest media surface
3 substances are coated
Nickel phosphorous, Cobalt alloy,
carbon coating
+ve points & cost are high

Read / Write heads

Ferrite heads
MIG heads
TF heads
MR/AMR heads
GMR heads
CMR heads
TMR heads

Ferrite heads
9 For Winchester disks
9 Made of iron oxide core wrapped with

electro magnetic coils
9 It is a u shaped iron core wrapped

with electrical windings
9 They are not so small in size

9 Used in hard disk up to 50 MB

Metal –In- Gap head
9 Same design as ferrite heads
9 Added a special metallic alloy on the
9 Usually found in hard disks of
about 50 MB – 100 MB

Thin Film Head
9 Very small & light weight heads
9 Instead of iron oxide, iron nickel
alloy core is used
9 Magnetically more powerful
9 It is costly compared to the other
two heads
9 Usually used in hard disks of
100 – 1000 MB capacities

Magneto Resistive Heads
9 Also known as Anisotropic MR
(AMR) heads
9 It is the key invention that led to the
creation of hard disks over 1 GB in size
9 Two separate heads, one for reading &
one for writing on a single assembly
9 Read head based on MR design & write
head based on Thin film head design
9 Commonly used in hard disks about
1 GB – 30 GB capacities

Giant MR Heads
9 Works on the same general
principles of MR heads
9 But uses some what different design that
makes them superior in several ways
9 The name “Giant” is not due to the size,
but due to the superior technology
9 By December 1997, IBM introduced their
first hard disk with GMR heads
9 They are more sensitive
9 GMR are used in latest technology
drives which capacities up to 75 GB

Colossal MR Heads
9 Know the GMR heads are taking over
the market
9 It is more sensitive & powerful than
the GMR heads

Tunnelling MR Heads
9 It is latest head design which will
increase the areal density too much
9 It is still under research

Head Arm/Head Slider
9 The arm on which the Read/Write head
is located
9 The size of a slider in a 3.5” size hard
disk is 0.08*0.063*0.017 inch
9 Slider of this size is called “Nano Slider”

Spindle Motor
9 It is the main motor which rotates the
hard disk drive platter
9 It is called Spindle motor because it is
directly connected to the Spindle on which
the platters are connected
9 Spindle motor rotates at a speed of
3600 to 7200 RPM or more

Logic Board
9 An intelligent circuit board is in built to
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