<s>
Compact	B-Application
disc	I-Application
manufacturing	I-Application
is	O
the	O
process	O
by	O
which	O
commercial	O
compact	O
discs	O
(	O
CDs	O
)	O
are	O
replicated	O
in	O
mass	O
quantities	O
using	O
a	O
master	O
version	O
created	O
from	O
a	O
source	O
recording	O
.	O
</s>
<s>
This	O
may	O
be	O
either	O
in	O
audio	O
form	O
(	O
CD-DA	O
)	O
or	O
data	O
form	O
(	O
CD-ROM	B-Device
)	O
.	O
</s>
<s>
burning	B-Application
used	O
for	O
CD-Rs	O
and	O
CD-RWs	O
)	O
as	O
the	O
pits	O
and	O
lands	O
of	O
a	O
replicated	O
CD	O
are	O
moulded	O
into	O
a	O
CD	O
blank	O
,	O
rather	O
than	O
being	O
burn	O
marks	O
in	O
a	O
dye	O
layer	O
(	O
in	O
CD-Rs	O
)	O
or	O
areas	O
with	O
changed	O
physical	O
characteristics	O
(	O
in	O
CD-RWs	O
)	O
.	O
</s>
<s>
All	O
CDs	O
are	O
pressed	O
from	O
a	O
digital	B-General_Concept
data	I-General_Concept
source	O
,	O
with	O
the	O
most	O
common	O
sources	O
being	O
low	O
error-rate	O
CD-Rs	O
or	O
files	O
from	O
an	O
attached	O
computer	O
hard	B-Device
drive	I-Device
containing	O
the	O
finished	O
data	O
(	O
e.g.	O
,	O
music	O
or	O
computer	O
data	O
)	O
.	O
</s>
<s>
Some	O
CD	O
pressing	O
systems	O
can	O
use	O
digital	B-Algorithm
master	I-Algorithm
tapes	O
,	O
either	O
in	O
Digital	B-General_Concept
Audio	O
Tape	O
,	O
Exabyte	O
,	O
Digital	B-Device
Linear	I-Device
Tape	I-Device
,	O
Digital	B-General_Concept
Audio	O
Stationary	O
Head	O
or	O
Umatic	O
formats	O
.	O
</s>
<s>
A	O
PCM	O
adaptor	O
is	O
used	O
to	O
record	O
and	O
retrieve	O
digital	B-General_Concept
audio	O
data	O
into	O
and	O
from	O
an	O
analog	O
videocassette	O
format	O
such	O
as	O
Umatic	O
or	O
Betamax	O
.	O
</s>
<s>
If	O
the	O
source	O
is	O
not	O
a	O
CD	O
,	O
the	O
table	O
of	O
contents	O
for	O
the	O
CD	O
to	O
be	O
pressed	O
must	O
also	O
be	O
prepared	O
and	O
stored	O
on	O
a	O
tape	O
or	O
hard	B-Device
drive	I-Device
.	O
</s>
<s>
In	O
all	O
cases	O
except	O
CD-R	O
sources	O
,	O
the	O
tape	O
must	O
be	O
uploaded	O
to	O
a	O
media	O
mastering	O
system	O
to	O
create	O
the	O
TOC	B-Application
(	O
Table	O
Of	O
Contents	O
)	O
for	O
the	O
CD	O
.	O
</s>
<s>
Contaminants	O
introduced	O
during	O
critical	O
stages	O
of	O
manufacturing	O
(	O
e.g.	O
,	O
dust	O
,	O
pollen	B-Application
,	O
hair	O
,	O
or	O
smoke	O
)	O
can	O
cause	O
sufficient	O
errors	O
to	O
make	O
a	O
master	O
unusable	O
.	O
</s>
<s>
The	O
laser	O
beam	O
recorder	O
uses	O
a	O
deep	O
blue	O
or	O
ultraviolet	B-Application
laser	O
to	O
write	O
the	O
master	O
.	O
</s>
<s>
The	O
developed	O
glass	O
master	O
is	O
placed	O
in	O
a	O
vapour	B-Algorithm
deposition	I-Algorithm
metallizer	O
which	O
uses	O
a	O
combination	O
of	O
mechanical	O
vacuum	B-General_Concept
pumps	O
and	O
cryopumps	O
to	O
lower	O
the	O
total	O
vapour	O
pressure	O
inside	O
a	O
chamber	O
to	O
a	O
hard	O
vacuum	B-General_Concept
.	O
</s>
<s>
Clear	O
polycarbonate	O
pellets	O
are	O
first	O
dried	O
at	O
around	O
130	O
degrees	O
Celsius	O
for	O
three	O
hours	O
(	O
nominal	O
;	O
this	O
depends	O
on	O
which	O
optical	O
grade	O
resin	O
is	O
in	O
use	O
)	O
and	O
are	O
fed	O
via	O
vacuum	B-General_Concept
transport	O
into	O
one	O
end	O
of	O
the	O
injection	O
moulder	O
's	O
barrel	O
(	O
i.e.	O
,	O
the	O
feed	O
throat	O
)	O
and	O
are	O
moved	O
to	O
the	O
injection	O
chamber	O
via	O
a	O
large	O
screw	O
inside	O
the	O
barrel	O
.	O
</s>
<s>
The	O
moulded	O
"	O
disc	O
"	O
(	O
referred	O
to	O
as	O
a	O
'	O
green	O
 '	O
disc	O
,	O
lacking	O
final	O
processing	O
)	O
is	O
removed	O
from	O
the	O
mould	O
by	O
vacuum	B-General_Concept
handling	O
;	O
high-speed	O
robot	O
arms	O
with	O
vacuum	B-General_Concept
suction	O
caps	O
.	O
</s>
<s>
At	O
this	O
point	O
the	O
discs	O
are	O
clear	O
and	O
contain	O
all	O
the	O
digital	B-General_Concept
information	I-General_Concept
desired	O
;	O
however	O
,	O
they	O
cannot	O
be	O
played	O
because	O
there	O
is	O
no	O
reflective	O
layer	O
.	O
</s>
<s>
The	O
discs	O
pass	O
,	O
one	O
at	O
a	O
time	O
,	O
into	O
the	O
metallizer	O
,	O
a	O
small	O
chamber	O
at	O
approximately	O
10−3	O
Torr	O
(	O
130	O
mPa	O
)	O
vacuum	B-General_Concept
.	O
</s>
<s>
There	O
is	O
a	O
load-lock	O
system	O
(	O
similar	O
to	O
an	O
airlock	B-Application
)	O
so	O
the	O
process	O
chamber	O
can	O
be	O
kept	O
at	O
high	O
vacuum	B-General_Concept
as	O
the	O
discs	O
are	O
exchanged	O
.	O
</s>
<s>
When	O
the	O
disc	O
is	O
rotated	O
into	O
the	O
processing	O
position	O
by	O
a	O
swivel	O
arm	O
in	O
the	O
vacuum	B-General_Concept
chamber	O
,	O
a	O
small	O
dose	O
of	O
argon	O
gas	O
is	O
injected	O
into	O
the	O
process	O
chamber	O
and	O
a	O
700	O
volt	O
DC	O
electric	O
current	O
at	O
up	O
to	O
20	O
kW	O
is	O
applied	O
to	O
the	O
target	O
.	O
</s>
