The CD in my disc drive became very warm after a movie was played. Can the disc actually catch on fire inside the CD player, or is this temperature nothing to worry about?
The Top Three Threats to Disk Media:
2. HEAT (yes HEAT Will damage CD/DVD media)
*CD/DVD media is like a sandwich, 2 clear, plastic disks, recordable layer, and adhesive adjoining them.
Don't run Dvd players, Xbox/Playstation, etc. on the rug! Perforated shelves, glass coffee table.....
Relevant and Valid question!
The answer is, don't worry. If you were foolish enough to load a severely distorted or a very heavily damaged or dirty disk, or maybe if the computer was in a factory getting all kinds of abrasive dirt into the drive, I guess things could get hot but you'd notice other problems (like it not playing your movie!) long before the heat was an issue.
However, just a couple of minor technical notes:
Someone said "...degradation of the magnetic layer..." It's not magnetic, there are several technologies used to store the data including chemical dyes, very thin layers of aluminium, silver or gold depending on the type of disk (before you ask - no it's not worth trying to recover the gold it would be worth less than one US cent per DVD.)
Secondly, the laser diodes in some writable DVDs are capable of generating quite intense heat. They are powerful enough to ignite things if they are removed from the drive and focussed on a flammable material for a few seconds (don't even think about trying it, even a reflected beam could cause severe eyesight damage). Having said that the heat is not a problem within an operating drive. The full power is only used for writing not reading, the temperature necessary for the chemical phase change of one bit of data is over 500C but only for less than 0.00000004 seconds and the heated area is around one tenth the width of a human hair.
You have some good answers so all I will add is that I have had CD's that feel very warm and they were fine. When they test these discs they put them under extreme heat to see how they hold up.
As Bruce points out, they are not particularly flammable and would need to get extraordinarily hot to catch fire, and will in fact melt before they burn (which will cause them to jam your drive). However, it is odd that your CDs get so warm as to raise concern. The friction of the air against the surface should not cause them to warm up much, and the laser (regardless of the debatable points raised by others) is both weak and lights up only one tiny point at a time, so the only explanation for the discs getting this warm is that other components in the drive/PC are getting even hotter and some of the dispersed heat is warming up the CD. So personally, I'd be more worried about the drive than about the CDs.
lasers do put off heat which is the final form of any type of energy. The lasers used in optical media is so low power, the amount of heat it puts off is insignificant unless there are some problems? When the temperature increase the plastic the cd is made from will lose its shape will lead to the degradation of the magnetic layer that the data is stored
Powerful laser diodes from DVD-RW drive
Between the friction being made from the disc spinning and the drive getting warm from spinning the disc, cd's and dvd's will get warm. Unless for some reason the laser gets a very large surge of power and produces high heat for a very long period of time, then fires will not happen. The laser does not produce enough heat to really be that noticeable. I would only worry if the disc and drive starts to smoke and is too hot to touch, which is extremely unlikely.
heat is produced due to the laser not due to friction of disk ... in that case disk would be damaged after a single run :P
Sorry, but the laser will not cause the dvd/cd drive to get hot. It is no different than a laser pointer; it will not get hot. Air friction from the disc spinning produces a little heat, but most of the heat is from the moving parts of the drive spinning very fast and bad air circulation within the drive. The poor air circulation is the worst part of the cd/dvd drive for computers as it traps the heat.
As for a guide to degradation of discs, this will give you some more information: http://www.clir.org/pubs/reports/pub121/sec5.html
Even when I play CDs/DVDs, they do get hot, but I guess that is normal and nothing to worry about. I assure you they do not get near to burning temperature. :D
With normal use, an optical disc should never come close to reaching the temperatures required to start a fire. You pretty much need to toss it in a fire, put it on a stove, etc in order to do it. Most players will only get the temp barely over 100 degrees F which is not even close to what is required to cause it to burn.