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3M's disc manufacturing method
https://forum.lddb.com/viewtopic.php?f=32&t=9092		 Page 1 of 1
Author:  kid_dynamo [ 28 May 2020, 15:09 ]
Post subject:  3M's disc manufacturing method
This is a question that's been bothering me for a while, I've heard it mentioned that 3M/Imation used a different disc manufacturing technique than the standard injection moulding process used by the other pressing plants, can anyone offer some clarification on this? How it actually differed and if it was exclusively a 3M thing. As I understand 3M discs are generally considered to be of pretty high quality despite using CLV instead of CAA, aside form a certain period when they were having a hard time maintaining quality control. I only have about a dozen 3M discs in my collection and aside from one with severe rot they all have excellent picture quality.
Author:  cplusplus [ 28 May 2020, 19:01 ]
Post subject:  Re: 3M's disc manufacturing method
Disclord posted some very insightful info here: The Day of the Triffids

2P (photo-polymerization) is sometimes called cold-casting or cold-pressing because it does not use the high temperature involved in the injection molding manufacturing process (hot PMMA is injected at a high pressure into a mold).

With the 2P manufacturing process, photopolymer plastic is stamped (transferring the pits) and then cured with UV light.
Author:  kid_dynamo [ 28 May 2020, 20:23 ]
Post subject:  Re: 3M's disc manufacturing method
That's facinating, I had no idea Phillips were responsible for bringing 3M into the laserdisc business. I knew there was a rivalry between Phillips and MCA ever since the latter tried to shift the blame for DiscoVision's faliure onto Phillips. Also interesting the cold-casting process was used by PDO UK as well, I find it very strange more manufactures didn't use a version of it as it seems to have been clearly superior to the high-temperature injection moulding process. Can't imagine the engineering challenge of getting a clean mould separation with a 12" disc.
Author:  sonicboom [ 29 May 2020, 15:23 ]
Post subject:  Re: 3M's disc manufacturing method
I'd like to attach a file from the Philips Technical Review, VOLUME 40, 1982, No. 10 which explains the Manufacture of LaserVision video discs by a photopolymerization process but alas the file is larger than the 2MB allowed here.

It goes into detail about PMMA and 2P

EDIT: I uploaded it to dropbox:
https://www.dropbox.com/s/luzyiwzrxtklk ... 2.pdf?dl=0
Author:  cplusplus [ 29 May 2020, 19:18 ]
Post subject:  Re: 3M's disc manufacturing method
sonicboom wrote:
It goes into detail about PMMA and 2P

Thank you for posting this. Very insightful!
Author:  je280 [ 29 May 2020, 22:26 ]
Post subject:  Re: 3M's disc manufacturing method
sonicboom wrote:
I'd like to attach a file from the Philips Technical Review, VOLUME 40, 1982, No. 10 which explains the Manufacture of LaserVision video discs by a photopolymerization process but alas the file is larger than the 2MB allowed here.

It goes into detail about PMMA and 2P

EDIT: I uploaded it to dropbox:
https://www.dropbox.com/s/luzyiwzrxtklk ... 2.pdf?dl=0


Thanks for that :thumbup: .
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