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pinto_zurich
Member

Join Date: Aug 2007
Posts: 9

Injection molding screw

04/17/2008 9:16 PM

Can any body help me to find the correct formula for calculating the compression ratio of General purpose injection molding screw?
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Delmar
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Join Date: Sep 2006
Location: Houston Texas
Posts: 282
Good Answers: 16
#1

Re: Injection molding screw

04/18/2008 11:10 PM

You might try the following forum to pick the brains of injection molders:

http://www.feedscrewdesigns.com/cgi-bin/forums/Ultimate.cgi

Regards, Delmar Schmidt
Melfi Technologies Houston
www.melfitechnologies.com

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plaasteek
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Join Date: Feb 2008
Location: Made in USA
Posts: 47
Good Answers: 3
#2

Re: Injection molding screw

04/19/2008 8:13 AM

The compression ratio is a comparison between the depth of the feed section of a screw in relationship to its metering section. You get this this by measuring the height of the top of the flight at the feed to the OD of its root. Do the same for the metering section and then divide the metering height into the feed height.

C.R. = Depth of Feed/Depth of Meter

Example: For a 2" diameter screw

C.R. = .340"/.170" = 2:1

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Previous in Forum: I need a lightweight plastic spool valve >100psi >10mm   Next in Forum: Sizing Exhaust Gas Vent on Condensing Furnace.

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