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Posts Tagged ‘CD Mass Production’

The Differences Between CD and DVD Duplication and Replication

Monday, January 4th, 2010

CD duplication or replication - there's a big difference, but what is it?

When making many copies of a disc, often it is easier just to hire a professional company to do it for you as it saves you time and, in the long run, money. But there are two different ways of making multiple copies of CDs and DVDs: The first is disc duplication and the second is disc replication. The two are not altogether foreign, but there are some subtle differences which can make a massive difference to which one is better suited to your needs.

The process behind disc duplication involves burning CDs or DVDs the way you would at home, in a disc burner using a laser. However, professional equipment is such that it can burn many copies of a disc at once, using disc burning towers. This makes the process much faster than it would be at home. The discs are then decorated and checked for quality in special machines.

On the other hand with disc replication, CDs or DVDs are copied using a master disc made from glass. This master disc literally punches the digital information onto the disc before the protective layers are added. It thus becomes part of the entire disc manufacturing process.

Although the initial costs of disc replication are more expensive because the glass master has to be made, if you want to make more than 1,000 copies of a disc it is actually cheaper than duplication. But duplication is much faster than replication: Duplication can take from 24 hours to three days, while replication takes between seven and ten days on average.

Also, the type of discs which can be made in both processes differ significantly: Disc duplication will only deal with CD-Rs or DVD+/-Rs, while replication is only for CD-ROMs or DVD-ROMs and also now Blu-Ray discs. This is because CD- and DVD-ROMs cannot be burnt upon and CD-Rs have been taken too far down the It can be hard to decide whether to duplicate or replicate CDs and DVDs so here's a table to make it clearermanufacturing process to then be stamped with the replicating machines. This seems trivial, but it can have a slight difference to which disc players can read them: It is estimated that in the current market that only 98% of CD players will play duplicated CDs while 90% of DVD players will play duplicated DVDs. This could have an effect on your decision: If you need to be able to guarantee your customers will be able to play your product, it is better to replicate the discs! This is because of the way that data is read from the different discs.

Aside from this, there are no real differences in appearance of the discs or the quality of data stored, though it should be noted that duplicated discs can be a little more susceptible to UV damage than replicated discs but this technicality is so slight it only really counts if you are planning on making your disc last more than thirty years!

Good luck with all your duplication and replication and I hope this article has helped you on the way to making your mind up on which is better suited to your needs. Just remember that the most important thing in the decision-making process is simply how many discs you are planning on creating: The basic rule is over a thousand, you replicate, under a thousand, you duplicate!

Have you ever wondered how a CD is made?

Friday, November 27th, 2009

Duplicating CDs is a complicated process

Compact Disc’s have become an intrinsic part of modern life.  They’re everywhere:  They carry our music, our work files, school projects, they come through our letterbox with adverts and hold the software for our computer programs.  In short, while twenty years ago they were a luxury, now we would be lost without them.

But haven’t you ever wondered how CD manufacturing works?  How are these discs put together and what are the resources that go into them?

The answer is not as complex as you might imagine:  There are five main layers to a CD.  However, because in the process of CD manufacturing, each layer must be produced separately so the manufacturing process has many stages and is quite detailed.

The first layer on a CD is thick and manufactured from Polyvinyl Chloride (PVC), a soft, clear polycarbonate plastic.  Interestingly, this layer makes up 99% of the CD the other four layers making up only 1% of it!  Thus, this layer is very important, serving two purposes:  First, it protects the data layer from scratches and secondly, like the lenses in spectacles, it helps the laser beam to focus on the data itself.  This layer of the CD is manufactured by feeding small granules of PVC into a hydraulic press where they are heated until they melt.  The molten plastic is then forced by a screw into a mould cavity and it takes on the round, CD shape.  The plastic is then allowed to cool and harden and a robotic metal arm removes it and stamps the hole into the middle.  This is called the ‘stacking ring’.

Next comes the ‘data layer’, perhaps the most complicated part of CD manufacturing.  The data on a CD consists of many pits and lands, bumps which go up and down and represent either a one or a zero.  They work in a way very similarly to binary on a computer or simple on and off switches in a light.  These pits and lands spiral out from the centre of the CD and are read and interpreted by a laser.  Unlike the vinyl, however, the data is read from the inside to the outside on a CD and not the other way around.  To place these very important pits and lands on the CD during the manufacturing process, a glass master copy of the data is made in the image of how the CD will look, using a powerful laser and something akin to a CD writer.  The glass master is then pressed against a metal disc to create a negative image of the CD, making a mould, or ‘press’.  (Hence the term ‘to press a CD’, or ‘CD pressing‘.)  Once the press has been made, the clear PVC disc is pushed against it, so that the data is imprinted on the surface of the disk itself.

This part of the process of CD manufacturing is a little different if the CD is a recordable one.  In this instance instead of a data layer, a photosensitive dye is applied.  This dye, when exposed to certain light which can be emitted from the lasers in CD writers, creates the impression of a pit.  Similarly, a re-recordable disk uses a dye, but a slightly different one which allows the laser to polarize the layer back and forth between a pit and a land.

The next stage in CD manufacturing is to place a thin layer of metal onto the PVC disc.  The metal is usually silver or aluminium but it can also be made from gold or other metals.  It is applied to the PVC disc on top of the data using a process called sputtering, which means that a surface, here the disk, is bombarded with small atoms of a substance, in this case the metal.  This makes the CD act as a mirror, reflecting the CD player’s laser back to the reader.  It’s also this that gives the underside of a CD its shiny appearance.

The CD manufacturing process is nearly done now and the last major physical change to the disc takes place:  A thin coating of lacquer applied in a ring around the centre of the CD and spread out to the edges by spinning the disk very fast.  The edges are also coated with lacquer.  This coating ensures the safety of the data and the foil, which are the most important parts of the CD to protect.

All the other parts of the CD manufacturing process are almost purely cosmetic, including the final layer, the application of the label which contains information about what is on the disk, who made it and possibly a few graphics, especially if it is a music CD or a film.

The disk is now ready to be printed and packed and it is only after this that we, the consumers, see the disk!  It is very rare that we actually appreciate the time and energy that goes into manufacturing a CD.  But now, next time you use one (which these days will probably be very soon) you can look at it and know exactly how it was made!

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