Replication Process
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Misconception: Understanding the replication process.

by Terry E. Mercer 1997-1999
Published by Replication News, 1998

This is only important, if you ever plan to go to replication with a CD or if your are just an "information monger." Many people will find it interesting. Other than the basics, all of the technical jargon has been removed (or defined, where necessary). Few replication plants allow for visitors, because of the clean room standards and the security issues. In the future, I will try to get some pictures of the various components and machines so you can see visual examples. For now, I hope my words will be descriptive enough.
I can honestly tell you that I would have never guessed the data was actually contained on a clear plastic part, and that even after nearly 500 CDR's under my belt, nothing in my mind even came close to the reality of the process. I hope my words can do the process justice, and that you find it as interesting as I did (and do).

Once you have a valid, verified pre-master (CDR with data on it, which you are verified to be complete, accurate, and written to the specs the particular replicator you are using to do the production) the process begins.
When the replicator receives the pre-master, they generally run a "quick" test to verify there are no flaws in the media. They DO NOT look at the data, programs, or information on the CD... if you have bugs, those bugs will be duplicated on each and every CD that comes from that pre-master. It is your responsibility to make sure there are no bugs. The replicator has the responsibility of making exact duplicates of the pre-master you sent them - no more, no less.
Once the initial verification has finished, the "Gold" is taken to the "Glass Mastering" phase. At this phase a "glass" impression of the CDR is made. From the Glass master a square "Stamper" made of metal is created. The stamper is then compared to the original CDR - are there any differences; if not - great; if so, where, how many (based on a ratio) and will those differences effect the data area?? If there are unacceptable differences, then a new glass master and stamper are made, and the testing is redone on the new stamper. If it fails a second time, then there are likely problems with the pre-master and a new CDR must be sent to the replicator. Once the stamper has passed the verification process, then it goes to "injection."
The actual making of a CD-ROM disc is quite interesting... and totally different than I initially assumed. Plastic is melted and "injected" into the stamper at a very high pressure. The plastic circle of clear plastic actually contains the pits, the hills and valleys, which physically contain the data. These clear plastic "cookies" are then placed flat and a resin is "spun" flat on the disc, then the reflective metal layer is added, more resin, and another protective layer of plastic, and another coat of resin to seal the disc.
It is quite interesting to watch.
The slightest speck of dust can cause problems in the finished product, so this whole process is conducted in ISO 9600 standard clean rooms.  Once the "donuts" ("cookies with icing" or the plastic disc containing the data and reflective coating and the resins) are finished, each and every disc is tested automatically by the replication equipment for thickness and proper information, are finished, the stacks of finished discs are taken to the silk screening room. 
Depending on the type of silk screening equipment, either one, two, five, or six screens are setup on the machine. One screen for each color. On CD's there is really no such thing as "four" color - it is generally five color, normal four color with the fifth being a white base coat to allow the four colors to be presented in there best possible style. Six color is the same as five color with the addition of a non-processed color, such as a neon or straight black. Most of the silk screeners use imperfect cookies to align the screens, and computerized laser lines help reduce the time required for proper registration (exact layering) of the screens.
Once everything is done, the screening process begins and finished CD's are dried and stacked on the other end of the machine. The finished stacks are called "spindles."  There are normally either 100 or 125 discs per spindle, and 4 spindles per box.

Questions or comments can be directed to Terry Mercer.


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