How Does
How Compact Discs Are Made
Contributor
By eHow Contributing Writer
Master Disc
-
The compact disc manufacturing process begins with a master disc that is made of glass. The glass disc is inserted into a machine that cleans the disc thoroughly. The machine uses a small brush (made of goat hairs) to wipe across the disc. While this disc is spinning, de-ionized water is added to the disc to ensure the disc is perfectly clean. Any additional water left on the glass is removed by the rapid motion.
Next, the glass disc is transported to another machine that inspects the disc for cleanliness. The machine uses a laser that sweeps across the glass, looking for dirt particles. Once the process is complete, the disc has a primer liquid and photo-resistant coating added to its surface. This protects the glass from becoming sensitive to light during recording. After the coating, it is dried in an oven for 30 minutes.
Finally, a solution is added to the disc to develop the information on its surface. Once it's added, the information is etched into the glass. Once the information etching is completed, a metal coating is added that consists of nickel and vanadium. This process results in the final master for producing disc copies. The master is then placed into emulsion for 70 minutes to finalize the glass and create the die (master used for copying).
Fabricating Discs
-
Once the master disc is created, it is stamped into the proper size to create the copy discs. The result is then used for the production of the discs.
To begin duplication, the die is carefully placed into a machine that creates discs molds out of a special plastic called polycarbonate. The result of this process is a hard translucent disc.
Next, a metal coating used to store data added to the surface of the translucent disc. In a quick process, the disc is coated with a thin layer of aluminum. The disc is placed onto a spindle, and a machine stamps the aluminum onto its surface.
Protection and Finishing
-
The final step of the process is protecting the disc. A coat of varnish is added to the surface. This varnish is dried onto the surface using ultraviolet lamps. After a few seconds, the varnish is dried and the disc is ready for printing.
Printing on the disc is completed using a rapid silkscreen machine. This machine has the ability to finish 70 discs per minute. If graphics aren't used on a disc, the company producing the disks usually adds their logo and lines to describe the discs contents.
Once the printing is complete, the discs are sorted and sent for packaging.
eHow Article: How Compact Discs Are Made
